# Quantum Computing Glossary — Part 3 — H-P

The glossary is too large for a single document (over 3,000 entries), so it is divided into six parts, plus the introduction:

# H-P

1. h. Symbolic name for the Planck constant. See also: h bar. See Wikipedia Planck constant article.
2. h bar. Symbolic name for the reduced Planck constant — the Planck constant divided by two times pi. See also: h. See Wikipedia Planck constant article.
3. H. See H gate.
4. H gate. See Hadamard gate.
5. Hadamard gate. A quantum logic gate (operation) which sets the quantum state for a qubit to a superposition of the |0> and |1> basis states, so that upon measurement it will have an equal probability of measuring as a |0> or a |1>. Technically, it performs two rotations: by 180 degrees around the X-axis, which flips |1> to |0> and |0> to |1>, and then a 90-degree rotation about the Y-axis, which leaves an input value of |0> pointing to the front of the Bloch sphere or an input of |1> pointing to the back of the Bloch sphere. [TBD: verify this]. It transforms an input of |0> to 1/SQRT(2)*(|0> + |1>) and an input of |1> to 1/SQRT(2)*(|0> — |1>). Commonly used in conjunction with a CNOT gate (controlled-NOT gate or controlled-X gateCX gate) to entangle two qubits. Abbreviated as H gate or H. See the Wikipedia Quantum logic gate article.
6. Hadamard spread. TBD. Referenced in the The role of Quantum Interference in Quantum Computing paper by Shiekh.
7. Hadamard transform. Perform a Hadamard gate in parallel on each of n qubits, which places the qubits into a superposition of 2^n discrete quantum states. Commonly used to prepare for quantum parallelism, to evaluate a computation on all 2^n quantum states simultaneously. Also referred to as a Walsh-Hadamard transform.
8. Hahn echo. See Hahn echo experiment.
9. Hahn echo experiment. Method used to measure the T2 time (dephasing time) of a qubit. See also: Ramsey experiment.
10. Hamiltonian. The operator in quantum mechanics which corresponds to the total energy of a quantum system. See the Wikipedia Hamiltonian (quantum mechanics) article.
11. Hamiltonian simulation. Use of a quantum computer to simulate the total energy of a quantum system, such as a particle or multiple bodies in physics, or atoms and molecules in chemistry. See the Wikipedia Hamiltonian simulation article.
12. hardware. The electrical, magnetic, mechanical, and material components which are used to assemble systems and devices. Collectively, a reference to a system or device which has been constructed from hardware components, exclusive of any software which may be used on or with such systems and devices. Commonly, in the context of quantum computing this is simply a reference to a quantum computer, in contrast to any software that might be used on that quantum computer. Commonly, in a more general context, this is a synonym for a machine or computer, in contrast to the software that might be used on that computer. May include firmware and possibly even operating system and system utilities.
13. hardware architecture. The overall, high-level hardware design for a machine, system, or device, including the instruction set architecture if the system is a computer.
14. hardware component. An electrical, electronic, magnetic, mechanical, or material component, in contrast to a software component. See also: device and subsystem.
15. hardware design. The conception and arrangement of electrical, electronic, magnetic, mechanical, and material components needed to implement the hardware for a machine, system, or device. The work of electrical engineers, including and especially computer engineers. See also: hardware architecture. Alternatively, the process of designing the hardware.
16. hardware-efficient algorithm. An algorithm which is carefully designed to make the most efficient use of the available hardware. This will generally be different between classical computers and quantum computers, and even between particular machine architectures of those two categories.
17. hardware efficient ansatz. See hardware-efficient ansatz.
18. hardware-efficient ansatz. TBD. A type of hardware heuristic ansatze. Abbreviated as HEA.
19. hardware efficient ansatzes. See hardware-efficient ansatzes.
20. hardware-efficient ansatzes. Plural for hardware-efficient ansatz.
21. hardware engineer. An electrical engineer or mechanical engineer responsible for some aspect of designing the hardware for a machine, system, or device. In contrast to software developers.
22. hardware feature. A specific capability or feature of a specific type of hardware.
23. hardware heuristic ansatze. TBD. Abbreviated as HHA. In contrast to physically-motivated ansatze (PMA).
24. hardware layout. How hardware components and their interconnections are arranged on a printed circuit board or an integrated circuit.
25. hardware native gateset. See hardware-native gateset.
26. hardware-native gateset. TBD.
27. Hartree-Fock procedure. TBD.
28. Hartree-Fock wavefunction. TBD.
29. Hartree-Fock wavefunction ansatz. TBD.
30. HEA. Initialism for hardware efficient ansatz. See also: HHA and PMA.
31. heat. Energy which has been absorbed by matter or lost or dissipated from one material to another material, causing motion or vibration, which is observed as heat. See the Wikipedia Heat article.
32. heat loss. Loss of energy due to dissipation of heat from a system. Alternatively, the loss of energy from a system due to the generation of heat.
33. Heisenberg interaction. TBD. Referenced in the Low-cost quantum circuits for classically intractable instances of the Hamiltonian dynamics simulation problem paper by Nam and Maslov, et al. See also: time-dependent Heisenberg interaction.
34. Heisenberg’s uncertainty principle. With certain pairs of quantum properties it is not possible to measure one without disturbing the value of the other. One such pair is position and momentum. See the Wikipedia Uncertainty principle article. Synonym for simply uncertainty principle. See also: classical uncertainty.
35. heralded controlled phase gate. See heralded quantum controlled phase gate.
36. heralded quantum controlled phase gate. TBD. See the Heralded quantum controlled phase gates with dissipative dynamics in macroscopically-distant resonators paper by Qin, Wang, Miranowicz, Zhong, and Nori. See also: controlled phase gate and quantum controlled phase gate.
37. hermitian operator. See Hermitian operator. Should be capitalized since it is based on a name, Charles Hermite.
38. Hermitian operator. A matrix representing an operator for a vector space which yields a real number. It must be a self-adjoint operator. In a quantum system, an operator corresponding to an observable must be a Hermitian operator, returning the real eigenvalue for the eigenvector corresponding to the observable. See the Wolfram Hermitian operator page or the Wikipedia Self-adjoint operator article. See also: Hermitian conjugate.
39. Hermitian adjoint. See Hermitian conjugate.
40. Hermitian conjugate. The transposition of the matrix representing a Hermitian operator in which each entry is replaced with the complex conjugate of the corresponding entry from the original matrix. See the Wikipedia Hermitian adjoint and Conjugate transpose articles. Synonym for Hermitian adjoint or Hermitian transpose.
41. Hermitian transpose. See Hermitian conjugate.
42. Hessian information. TBD.
43. heuristic. A clever shortcut to a solution to a problem which bypasses most complexity and alternatives without needing to explicitly evaluate them. May yield an approximate solution rather than the optimal solution, but with significantly less effort and resources than the optimal solution. May not work as expected in all situations or for all cases — there are no guarantees. May not scale, or may work better at larger scale than smaller scale — may perform differently at different scales. Its appropriateness must be evaluated on a case-by-case basis.
44. heuristic quantum algorithm. A quantum algorithm which employs the use of a heuristic or other form of shortcut to achieve an approximate, sufficient, or practical solution rather than an absolutely exact, perfectly optimal solution. The motivation is either speed, less resources, or simplicity of the algorithm.
45. hexadecimal digit. A single character representing an integer value in a 4-bit integer or nibble. The characters 0 to 9 represent the integer values 0 to 9. The letters A to F or a to f represent the integer values 10 to 15. Two hexadecimal digits can be used to represent the two nibbles of a byte, and four hexadecimal digits can be used to represent the four nibbles of a 16-bit integer. And so on, for 32-bit integers and 64-bit integers, and for character strings as well.
46. HHA. Initialism for hardware heuristic ansatze. See also: PMA and HEA.
47. hierarchy of classes. In object-oriented programming (OOP), the subclasses and superclasses of all OOP classes define a hierarchical ordering of the classes. The position of an OOP class in that hierarchy defines which data items and functions the class will have access to — all (or selected) data items and functions in that class and from all levels of the hierarchy above that class. Alternatively, the concept of a hierarchy of classes applies to any form of class, unrelated to object-oriented programming (OOP), also referred to as a taxonomy of classes.
48. high complexity. A level of complexity which indicates that it will be difficult to comprehend and control a system.
49. high connectivity between qubits. Exact meaning unclear. General reference to quantum entanglement of qubits in a quantum computer. May indicate that the qubits of a given quantum computer are collectively highly entangled. Conceptually, it could be high-dimension entanglement. [TBD: clarify this]
50. high degree of entanglement. TBD.
51. high-dimensional entanglement. See high-dimensional quantum entanglement.
52. high-dimensional quantum entanglement. Quantum entanglement when there are more than two quantum states per qubit, such that there may be more than two entanglements between a pair of qubits. Research is being pursued in this area mainly for quantum communication, where channel bandwidth is more critical. Current quantum computers and near-term quantum computers are limited to a superposition of two quantum states for a single observable per qubit.
53. high-dimensional quantum system. A quantum system of more than two dimensions, such as a quantum computer based on qutrits (three dimensions) or qudits (ten dimensions.)
54. high-dimensional system. See high-dimensional quantum system.
55. high dimensionality. A quantum system with more than the two dimensions of each qubit, such as a quantum computer based on qutrits with a dimensionality of three or qudits with a dimensionality of ten. This concept is not utilized in current quantum computers or projected near-term quantum computers, but there is research for use in quantum communication systems and it might be utilized in less-near future quantum computers. Synonym for higher dimensionality.
56. high-end quantum computer simulator. A quantum computer simulator which is running on a high-end classical computer, typically a high-end server on the Internet, such as a cloud-based quantum service, to boost the performance of the simulation.
57. high-end server. More powerful server based on a classical computer.
58. high-level language. Any programming language which has more expressive power than the basic instructions of the machine architecture as in an assembly language, including algebraic expressions, data structures, and control structures.
59. high-level programming language. See high-level language.
60. high-level quantum language. See high-level quantum programming language.
61. high-level quantum programming language. A programming language for a quantum computer comparable in expressive power to the high-level languages of a classical computer. Anything above the level of an assembly language or a low-level quantum intermediate representation.
62. high-performance. Relating to high performance.
63. high performance. A level of performance which significantly exceeds the performance of a typical computer system or application.
64. high-performance computer. A classical computer, typically a server, whose performance and capacity is significantly greater than for average servers. Generally, excludes supercomputers since they are their own category, far beyond even the more capable high-performance computers. Abbreviated as HPC. See the Wikipedia Supercomputer article.
65. high-performance computing. Classical computing based on high-performance computers. Abbreviated as HPC. See the Wikipedia Supercomputer article.
66. high qubit coherence. The ability of a qubit to maintain its quantum state for more than the execution of a few quantum logic gates. Generally more than 20 microseconds.
67. higher-dimensional quantum system. See high-dimensional quantum system. See also: lower-dimensional quantum system.
68. higher-dimensional system. See high-dimensional system. See also: lower-dimensional system.
69. higher dimensionality. See high dimensionality. See also: lower dimensionality.
70. higher-level language. See high-level language. Alternatively, may be a more modern programming language which has even greater expressive power than traditional high-level languages.
71. higher-level programming language. See higher-level language.
72. highly entangled. Most possible pairs of qubits of a quantum computer are or can be entangled simultaneously, in contrast with fully entangled, where all possible pairs of qubits may be entangled, minimally entangled, where only a few pair of qubits are or can be entangled, or partially entangled, where there is no requirement that most pairs are or can be entangled. Technically, highly entangled is also partially entangled. [TBD: verify].
73. Hilbert space. A mathematical vector space, which for a quantum system corresponds to all possible quantum states of the quantum system, such as for a quantum computer. A very mathematical concept which is technically true and relevant to quantum mechanics and quantum computing, but not needed for the average user of a quantum computer. See Wikipedia Hilbert space article.
74. Hilbert space dimension. See Hilbert space dimensionality.
75. Hilbert space dimensionality. Dimensionality of a Hilbert space — the count of dimensions of a vector space. The dimensionality of a quantum system. See the Testing the Hilbert space dimension paper by Brunner, Pironio, Acin, Gisin, Methot, Scarani.
76. holonomic. TBD.
77. holonomic CNOT gate. Short for holonomic controlled-NOT quantum logic gate.
78. holonomic CNOT logic gate. Short for holonomic controlled-NOT quantum logic gate.
79. holonomic CNOT quantum gate. Short for holonomic controlled-NOT quantum logic gate.
80. holonomic CNOT quantum logic gate. Short for holonomic controlled-NOT quantum logic gate.
81. holonomic controlled-NOT gate. Short for holonomic controlled-NOT quantum logic gate.
82. holonomic controlled-NOT logic gate. Short for holonomic controlled-NOT quantum logic gate.
83. holonomic controlled-NOT quantum gate. Short for holonomic controlled-NOT quantum logic gate.
84. holonomic controlled-NOT quantum logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
85. holonomic controlled-Z gate. Short for holonomic controlled-Z quantum logic gate.
86. holonomic controlled-Z logic gate. Short for holonomic controlled-Z quantum logic gate.
87. holonomic controlled-Z quantum gate. Short for holonomic controlled-Z quantum logic gate.
88. holonomic controlled-Z quantum logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
89. holonomic CZ gate. Short for holonomic controlled-Z quantum logic gate.
90. holonomic CZ logic gate. Short for holonomic controlled-Z quantum logic gate.
91. holonomic CZ quantum logic gate. Short for holonomic controlled-Z quantum logic gate.
92. holonomic CZ quantum gate. Short for holonomic controlled-Z quantum logic gate.
93. holonomic gate. Short for holonomic quantum logic gate.
94. holonomic gate process tomography. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
95. holonomic H gate. Short for holonomic Hadamard quantum logic gate.
96. holonomic H logic gate. Short for holonomic Hadamard quantum logic gate.
97. holonomic H quantum gate. Short for holonomic Hadamard quantum logic gate.
98. holonomic H quantum logic gate. Short for holonomic Hadamard quantum logic gate.
99. holonomic Hadamard gate. Short for holonomic Hadamard quantum logic gate.
100. holonomic Hadamard logic gate. Short for holonomic Hadamard quantum logic gate.
101. holonomic Hadamard quantum gate. Short for holonomic Hadamard quantum logic gate.
102. holonomic Hadamard quantum logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
103. holonomic logic gate. Short for holonomic quantum logic gate.
104. holonomic quantum computation. TBD. Abbreviated as HQC. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
105. holonomic quantum gate. Short for holonomic quantum logic gate.
106. holonomic quantum logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
107. holonomic single-qubit gate. Short for holonomic single-qubit logic gate.
108. holonomic single-qubit logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
109. holonomic two-qubit gate. Short for holonomic two-qubit logic gate.
110. holonomic two-qubit logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
111. holonomic X gate. Short for holonomic X quantum logic gate.
112. holonomic X logic gate. Short for holonomic X quantum logic gate.
113. holonomic X quantum gate. Short for holonomic X quantum logic gate.
114. holonomic X quantum logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
115. holonomic X, Y, and Z gates. Short for holonomic X, Y, and Z quantum logic gates.
116. holonomic X, Y, and Z logic gates. Short for holonomic X, Y, and Z quantum logic gates.
117. holonomic X, Y, and Z quantum gates. Short for holonomic X, Y, and Z quantum logic gates.
118. holonomic X, Y, and Z quantum logic gates. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
119. holonomic Y gate. Short for holonomic Y quantum logic gate.
120. holonomic Y logic gate. Short for holonomic Y quantum logic gate.
121. holonomic Y quantum gate. Short for holonomic Y quantum logic gate.
122. holonomic Y quantum logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
123. holonomic Z gate. Short for holonomic Z quantum logic gate.
124. holonomic Z logic gate. Short for holonomic Z quantum logic gate.
125. holonomic Z quantum gate. Short for holonomic Z quantum logic gate.
126. holonomic Z quantum logic gate. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
127. host computer. The classical computer used to control a quantum computer. It runs a host program which contains the control logic needed to fully control the execution of a quantum program.
128. host program. The code, running on a host computer, a classical computer, which is the control logic which supervises, monitors, and controls the execution of a quantum program on a quantum computer or a quantum simulator. See control logic for details.
129. hosted cloud service. See cloud-based service.
130. HPC. Initialism for high-performance computer or high-performance computing.
131. HQC. Initialism for hybrid quantum-classical or hybrid quantum-classical algorithm.
132. HTTP. The Internet protocol for communicating over the Internet with a web site.
133. hybrid algorithm. See quantum hybrid algorithm.
134. hybrid classical quantum algorithm. See quantum hybrid algorithm and hybrid computation.
135. hybrid computation. See hybrid mode of operation.
136. hybrid mode of operation. A computation in which portions are executed on a quantum computer and portions on a classical computer. For example, if conditional execution, looping, function calls, or data structures and storage in files or databases are needed, such as when there is a large volume of data or operations or logic which are not easily represented as a quantum logic circuit. See the A Practical Quantum Instruction Set Architecture paper by Smith, Curtis, and Zeng of Rigetti Computing.
137. hybrid of classical computing and quantum computing. See hybrid mode of operation.
138. hybrid quantum-classical. An approach that uses a blend of quantum computing and classical computing, leveraging the strengths of both. Abbreviated HQC.
139. hybrid quantum-classical algorithm. TBD. Abbreviated HQC.
140. hybrid quantum-classical algorithms for chemistry. TBD.
141. hybrid quantum/classical computing. See quantum/classical hybrid algorithm and hybrid mode of operation.
142. i. Symbol used after a real value to indicate that it is actually an imaginary value.
143. I. See I gate.
144. I gate. A quantum logic gate which performs the identity operation on a qubit. This should not change the quantum state of the qubit, but quantum noise and decoherence may in fact change the quantum state.
145. i.i.d. Initialism for independent and identically distributed. See also: i.i.d. quantum source.
146. i.i.d. quantum source. Short for independent and identically distributed quantum source.
147. ideal logical qubit. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
148. identical. Two entities which can not be distinguished. Separate identities cannot be established for the entities.
149. identical matrix. Two matrices which are identical — they have the same dimensions, and the same values for all entries.
150. identifier. A label or name which identifies an entity, such as a data item, function, variable, class, or program. Some identifiers may be required to be unique, while others may be unique only within a limited context. See also: proper name.
151. identify. Some method of determining the identity of an entity. May be via an identifier or by characteristics, qualities, and attributes.
152. identity. The quality of an entity being distinct from other entities. May be an individual identity or a group identity. The former uniquely identifies the individual entity while the latter establishes membership in a group such as a class or type.
153. identity matrix. The square matrix which when multiplied against any square matrix of the same dimensions yields that same, identical matrix. Also, multiplying a matrix by its inverse matrix produces the identity matrix. See the Wikipedia Identity matrix article.
154. identity operation. Applying the identity matrix to the quantum state of a qubit. In theory, this should not change the quantum state of the qubit, but quantum noise and decoherence may in fact change the quantum state.
155. image. Two-dimensional projection of a subset of a real or imaginary physical system as a matrix or lattice of image elements.
156. image capture. The process of collecting all of the image elements for an image as it is imaged. See also: imaging.
157. image element. The unit for image capture and image processing. A pixel in classical computing. Might quantum computing offer a different approach to image elements?
158. image generation. The process of artificially constructing an imaginary image. See also graphical image generation.
159. image processing. Computation on the image elements of an image. See also: video processing. A very tedious and computationally-intensive process on a classical computer. Includes element-level processing, filtering, focusing, object detection and recognition, object extraction, scene recognition, feature recognition, text recognition, etc. Potential for acceleration on a quantum computer which could lead to whole new avenues of processing which are today unrealizable, but that would probably require a very large number of qubits. See also: video processing, audio processing, and graphical image processing.
160. image sensor. A device (sensor) for capturing images, such as in a digital camera or a digital video camera.
161. imaged. Imaging after it has been completed.
162. imaginary. See imaginary number.
163. imaginary image. An image constructed or derived from human imagination, random numbers, or the output of a model. See also: image generation.
164. imaginary number. A number which has the same form as a real number and a corresponding range of values, but is not a true real number. The non-real part of a complex number. It does not represent any real quantity. Commonly represented as a real value followed by the i symbol. See the Wikipedia Imaginary number article and the Wikipedia Complex number article.
165. imaginary part. The non-real portion of a complex number. Depending on context, this may refer to the real value of the imaginary part, or it could refer to the imaginary part as an imaginary number, which is a real number multiplied by the square root of minus 1 (-1). Squaring the latter would multiply the real value by minus 1 (-1). Unless the context is very clear, the reference is to the real value — the b of a + bi. See also: real part.
166. imaginary-time variational quantum simulator. TBD.
167. imaginary value. See imaginary number. Or an algebraic expression which evaluates to a real value, followed by the i symbol.
168. imagine. Conceive of an entity independent of whether it might actually exist. See also: contemplate and theorize.
169. imaging. The act of forming the two-dimensional projection for an image. See also: image capture
170. imbalance of charge. An atom which does not have a balance of charge — the count of protons is not the same as the count of electrons. Alternatively, the exact degree of imbalance of charge — the count of protons minus the count of electrons.
171. immunity to environmental noise. The resilience of a hardware circuit or component in the presence of any external electromagnetic radiation or magnetic fields. May be due to shielding or the construction of the device itself. See the Superconducting Caps for Quantum Integrated Circuits paper by O’Brien, Vahidpour, Whyland, Angeles, Marshall, Scarabelli, Crossman, Yadav, Mohan, Bui, Rawat, Renzas, Vodrahalli, Bestwick, and Rigetti.
172. imperfectly implemented quantum operation. TBD.
173. imperfect operation. TBD.
174. imperfect quantum operation. TBD.
175. implement. Transform an algorithm, design, or specification into working code or a circuit. Perform the implementation process.
176. implementation. The result produced by the implementation process. Alternatively, the implementation process itself. The code is the implementation of the algorithm and design.
177. implementation process. The process of transforming an algorithm, design, or specification into code or a circuit.
178. in silico. Use of a computer to simulate a biological or chemical process. In contrast to a biological or chemical experiment. See the Wikipedia In silico article.
179. in-silico VQE. TBD.
180. incoherent ancilla. TBD.
181. incoherent operations. TBD.
182. independent and identically distributed. TBD. Abbreviated as i.i.d. See also: independent and identically distributed quantum source.
183. independent and identically distributed quantum source. TBD. Abbreviated as i.i.d. quantum source.
184. index. Position of an item in a list, as an integer. Alternatively, a data structure which allows data to be indirectly accessed or associatively accessed by a key or key value.
185. indirect access. A method for accessing data through indirect means, such as using a key, index, or query. See also: associative access.
186. indirectly accessed. See indirectly access.
187. individual. See individual entity.
188. individual entity. An entity distinct from all other entities, in contrast to a group of entities or all entities.
189. individual identity. Identity for an individual entity, as distinct from group identity.
190. individual member. See individual member of a group.
191. individual member of a group. See individual members of a group. An individual which belongs to a particular group.
192. individual members of a group. The individuals who are members of a group of entities, emphasizing their individual identity rather than collectively as one.
193. individually controlled qubits. Odd, infrequently used term, which is redundant for all current quantum computers, where every qubit can of course be individually controlled using quantum logic gates which can reference specific qubits.
194. induced error. See environmentally-induced error.
195. inductance. Loosely, the amount of energy which can be stored by an inductor and the frequencies of current which may pass through the inductor.
196. inductor. An electronic component which stores energy in a magnetic field and moderates the flow of current through the device. See the Wikipedia Inductor article. See also: inductance and capacitor.
197. inefficiently computable function. A computable function for which the length of the computation scales superpolynomially with the input size. In contrast to an efficiently computable function which scales polynomially with the input size.
198. information. Data which has at least some limited structure, such as records or rows in a table. See also: structured information, semi-structured information, unstructured information, knowledge, and insight. Alternatively, simply a synonym for data.
199. infrared. See infrared radiation.
200. infrared light. See infrared radiation.
201. infrared radiation. Electromagnetic radiation which is just below the threshold for visible red light, with a slightly lower frequency and slightly longer wavelength. People cannot directly see infrared radiation, but they can feel it as heat. See the Wikipedia Infrared article. Shortened as infrared. Abbreviated as IR. See also: ultraviolet radiation.
202. inherent computational advantage. For a quantum computer, superposition and entanglement of quantum states provide a degree of parallelism which is inherently superior to the capabilities of a classical computer. Alternatively, simply the fact that some quantum computers have enough qubits that they can no longer be simulated on a classical computer for a broad class of quantum algorithms.
203. inherit. In object-oriented programming (OOP), a subclass is granted access to all (or some) of the data items and functions of its parent class and the superclasses of its parent class. It inherits that access.
204. inheritance. In object-oriented programming (OOP), the fact that a subclass has access to data items and functions of its parent class and any superclasses of its parent class. Those data items and functions are inherited from the superclasses. See also: multiple inheritance.
205. inherited. In object-oriented programming (OOP), the data items and functions of the parent class of a subclass and the superclasses of its parent class to which the subclass will be granted access. It inherited that access.
206. initial state. The desired state of a system when in comes into existence or processing begins. See also: final state. There may be a default or the user may be required to specify the state.
207. initial value. The desired value of a variable when a program or object comes into existence or when processing begins. There may be a default or the user may be required to specify the value.
208. initialization. Processing which must be performed before a system can begin its normal processing, such as to initialize both state and variables.
209. initialize. To provide the initial value for a variable or the initial state of a system.
210. inner degree of freedom. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
211. inner product. TBD. See also: dot product. See the Wolfram MathWorld Inner Product page.
212. inner product space. A vector space which provides an inner product. See the Wikipedia Inner product space article.
213. inner-product space. See inner product space.
214. input. See input value. Alternatively, input data — all input values to be provided to an entity so that it can process them, as well as configuration parameters. See also: output.
215. input data. All input values to be provided to an entity so that it can process them. Synonym for input. See also: configuration parameter and output data.
216. input value. A data value or signal to be provided to a system, application, component, device, process, function, mapping, or code so that it can perform its processing. See also: argument and output value.
217. insight. A deep, intuitive, nuanced, and enlightening understanding of some matter, especially if it unlocks doors and sheds light on other matters, in contrast to simply superficial knowledge. Can quantum computers help us gain insight?
218. instruction. The classical computing equivalent of a quantum operation or a quantum logic gate. The equivalent of a sequence of instructions for a classical computer would be a quantum circuit on a quantum computer.
219. instruction set. See instruction set architecture.
220. instruction set architecture. A detailed specification of the set of operations or instructions that a computer can execute, including any internal data and control resources, such as registers and memory which can be accessed by those instructions, as well as any data formats which are relevant to both instructions and internal data and control resources. Either a classical instruction set architecture or a quantum instruction set architecture. Both overview and details for an instruction set architecture would be found in a principles of operation document.
221. insulating substrate. The surface on which the electronic components and interconnections of an integrated circuit are fabricated. This surface is electrically neutral, an insulator, assuring that electric charge can only move between electronic components via explicit interconnections. Can be abbreviated simply as substrate.
222. insulator. A material which is electrically neutral and inhibits the transmission of electric charge, with the exception of a Josephson junction which permits the tunneling of electrons through an insulator, but in a controlled fashion. In contrast to a conductivity, which facilitates transmission of electric charge.
223. integer. The normal mathematical meaning — a whole number, a number without a fraction. See also: real, complex number. See the Wikipedia Integer article.
224. integer factorization. See integer factorization problem.
225. integer factorization problem. The problem of finding the collection of integers whose product is a given integer. The values in that collection are are not necessarily prime numbers (other than the degenerate sequence of 1 and the number itself.) See the Wikipedia Integer factorization article. Required for cryptography which is based on keys which are large prime numbers. See also: prime factorization problem.
226. integer number. A number which is an integer. It has no fractional digits.
227. integer value. A value which is an integer.
228. integrated circuit. One or more electronic circuits whose electronic components and interconnections have been fabricated onto an insulating substrate, in contrast to a printed circuit board containing discrete electronic components — and integrated circuits as well. The substrate will then be placed in some type of chip package which can then be inserted or otherwise fastened onto a printed circuit board. Abbreviated as IC. Commonly referred to as a chip. See the Wikipedia Integrated circuit article.
229. integrated fabric of programmable quantum devices. Qubits arranged in a grid or lattice (fabric) which facilitates coupling between qubits. The qubits themselves may be arranged in a grid, or they may be lined on the edges of the grid and it is the interconnections which comprise the grid. Marketing term used by D-WAVE Systems in their The D-Wave 2000Q™ Quantum Computer Technology Overview.
230. interconnections. The connections between electronic components of an electronic circuit, especially on an integrated circuit, but on a printed circuit board as well. Alternatively, references or includes cables, wiring, waveguides, and wireless connections as well when considered a larger system, multiple systems, or remote devices.
231. interference. See quantum interference. TBD.
232. intermediate format. A data format between a source format and a final format. There may be any number of such intermediate formats, such as one for each step or stage of transformation or processing, each of which performs a transformation of data, information, or code to either a different data format or a modified version of the same data format. Synonym for intermediate representation.
233. intermediate measurement. Measurement performed before the completion of a quantum circuit. The outcome of the intermediate measurement may be used to influence the choice of what quantum logic gates will follow. See also: quantum intermediate measurement.
234. intermediate representation. A data format which is a transformation of an original, source format of data or code, but not the final format which can be directly processed by its intended destination — it will need to be transformed again before it can be directly processed. Abbreviated as IR. An IR can be used as a common format so that a variety of different tools can operate on the IR without knowledge of the final format, which may be too esoteric or machine-specific to present an opportunity for wide sharing of the tool. For example, a programming language compiler could be applicable to more than one type of machine by transforming the source code for the program into an intermediate representation which is independent of the type of machine, which can then be transformed by other tools into the code format needed for executable code for the target machine.
235. Internet protocol. A protocol for communicating with an Internet service, such as HTTP for web sites.
236. interpreter. See virtual machine. Software which can execute a program without the need to compile it into machine language. Common for more specialized programming languages which are either too complex for direct compilation to machine language or used for purposes where the raw speed of machine language is not strictly needed. See also: simulator.
237. inter-process communication. See interprocess communication.
238. interprocess communication. A method for passing information between two processes. See also: process synchronization. See the Wikipedia Inter-process communication article.
239. interval. A gap or period of time or space. May be a discrete interval or a continuous interval.
240. interval of time. A gap or period of time. Generally, of fixed length. Generally, repeated. Alternatively, a particular period in time. Either a discrete interval of time or a continuous interval of time.
241. intractable. Current methods and technologies are unable to cope. See also: intractable problem.
242. intractable problem. A problem for which current methods and technologies are unable to arrive at a solution. Alternatively, a solution can be found, but the cost or other criteria might make it unacceptable.
243. introduction to quantum computing. See first introduction to quantum computing.
244. ion. A particle, either an atom or molecule, which acts as a charged particle as a result of losing one or more of its electrons or gaining extra electrons, such that the number of protons and electrons of the particle are not equal. It may have a net positive charge or a net negative charge, depending on whether it has a deficit or surplus of electrons. See the Wikipedia Ion article.
245. ion trap. Any method of capturing and containing a charged particle (ion) using electrical or magnetic fields. Can be used to construct a qubit for a quantum computer. See Wikipedia Ion trap article. Also known as trapped ion. See trapped Rydberg ion.
246. ion trap quantum computer. Any quantum computer whose qubits are based on ion traps. See the Wikipedia Trapped ion quantum computer article. Also known as trapped-ion quantum computer. See trapped Rydberg ion quantum computer.
247. ion trap quantum computing. Quantum computing on an ion trap quantum computer. Technically, algorithms should not be so different from algorithms on any other gate-based quantum computer.
248. ion trap qubit. A qubit based on an ion trap. See trapped Rydberg ion qubit.
249. ion-trapped quantum computer. See ion trap quantum computer.
250. IPEA. Initialism for iterative quantum phase estimation algorithm.
251. IR. Initialism for intermediate representation, infrared, or infrared radiation.
252. Ising coupling. TBD. See the Robust Ising Gates for Practical Quantum Computation paper.
253. Ising (XX) gate. TBD. See the Robust Ising Gates for Practical Quantum Computation paper. See the Wikipedia Quantum logic gate article, but even it is vague.
254. Ising (zz) coupling gate. TBD. See the Robust Ising Gates for Practical Quantum Computation paper.
255. Ising interaction. TBD. See the Robust Ising Gates for Practical Quantum Computation paper.
256. isolation. Quality of a system that its state is not dependent on or impacted by the surrounding environment. This quality is achieved and maintained by shielding from stray electromagnetic radiation, physical separation, and low energy and low temperature.
257. item. An object or value. See data item or list item. Synonym for element.
258. Iteration. A repetition of something, such as execution of code or execution of a quantum logic circuit, or any arbitrary process. Alternatively, the general process of iterating or repeating some sort of processing.
259. isolated. Not in direct contact with or affected by the surrounding environment.
260. isolated quantum system. Redundant term — all quantum systems are presumed to be isolated, otherwise they would not be considered true, complete systems. The un-isolated system would need to be expanded until it was essentially isolated from any surrounding environment. See quantum system.
261. iSwap. See ISWAP.
262. ISWAP. See ISWAP gate.
263. iSwap gate. See ISWAP gate.
264. ISWAP gate. A quantum logic gate which swaps the quantum state of two qubits plus a phase shift — applying a minus i phase shift to the first qubit if it is in the |1> basis state and applying a minus i phase shift to the second qubit if it is in the |0> basis state. Abbreviated as ISWAP. Use the PSWAP gate to apply a more specific phase shift angle. [TBD: 1) is it a shift of phase or a setting of phase and 2) is the condition before the swap or of the state being swapped in?] Referenced in Source Code Documentation — pyquil.api from Rigetti Computing. See also: SWAP gate, CSWAP gate, and PSWAP gate.
265. iterative quantum phase estimation algorithm. TBD. Abbreviated as IPEA.
266. joint state. TBD.
267. Jordan-Wigner encoding. TBD.
268. Jordan-Wigner mapping. TBD.
269. Jordan-Wigner representation. TBD.
270. Jordan-Wigner transform. TBD.
271. Jordan-Wigner transformation. TBD.
272. Josephson effect. The effect of quantum mechanics which enables electrons to tunnel across an insulator placed between two superconductors. Josephson junctions are electronic devices which exploit this effect. See the Wikipedia Josephson effect article. See also: quantum transistor.
273. Josephson junction. An electronic component which exploits the Josephson effect. Commonly used to construct a superconducting quantum computer. Commonly a pi Josephson junction. See the Wikipedia Pi Josephson junction article.
274. KAK coefficients. TBD.
275. KAK form. TBD.
276. KAK interaction coefficients. TBD.
277. ket. Used to describe a quantum state. The Hermitian conjugate of the bra of a bra-ket. Represents a column vector. See bra-ket notation. See also: bra and Dirac notation. For example, |0> and |1> are kets, as are |101> and |001011>.
278. ket notation. See ket and bra-ket notation. Those are the two proper terms — there is no separate ket notation.
279. key. May be an encryption key to control access to data or a key value used to indirectly access data. See also: cryptographic key and public-key cryptography.
280. key value. A value which uniquely identifies a particular collection of data items in a larger collection of data, permitting the data items to be indirectly accessed.
281. keyword. A simple natural language word, although the exact syntax may be more specialized than simply letters. Alternatively, a subset of words which have special or at least more significant meaning than most other words.
282. keyword search. Search that is optimized for words, keywords, and phrases in natural language text or in any textual value which has a syntax which represents words or keywords. See also: search engine.
283. KLM quantum computation. Short for Knill-Laflamme-Milburn quantum computation.
284. Knill-Laflamme-Milburn type quantum computation. See Knill-Laflamme-Milburn-type quantum computation.
285. Knill-Laflamme-Milburn-type quantum computation. See Knill-Laflamme-Milburn quantum computation.
286. Knill-Laflamme-Milburn quantum computation. TBD. Read the Efficient Linear Optics Quantum Computation paper by Knill, Laflamme, and Milburn.
287. knowledge. Understanding of some matter, from basic facts, to simple and complex relationships, to general principles, in contrast to simply data and simple information. See also: insight. Can quantum computers help us expand our knowledge? Can quantum computers consume and express knowledge, in contrast to simply data?
288. Kronecker product. The outer product of two matrices, which produces a larger matrix with dimensions which are the product of the original dimensions — m x n times p x q produces an mp x nq matrix. See Wikipedia Kronecker product article. Synonym for tensor product.
289. label. A name used to identify an entity, possibly to indicate its type, ownership, or other association.
290. language. The class of expressions which can be constructed according to the syntax rules of a grammar, such that an automaton or state machine constructed according to the syntax rules of the grammar is capable of recognizing the structure, detail, and meaning of those expressions. Includes natural languages, programming languages, and specialized languages.
291. large problem. Vague notion of a problem of significant size. Size is in the eye of the beholder. Simply in contrast to tiny, small, modest, and moderate or medium size. Towards the higher end of the spectrum of problem sizes.
292. large-scale quantum computer. May simply be a synonym for a general purpose quantum computer, with emphasis on it’s capacity to handle large problems. Could conceivably be a fixed-function quantum computer, emphasizing its capacity but not its range of function. Alternatively, simply a synonym for large-sized quantum computer, based on qubit count.
293. large-scale quantum computing. Computing using a large-scale quantum computer.
294. large-scale quantum processor. TBD.
295. large-scale universal quantum computer. Large-scale quantum computer with emphasis on its ability to be applied to a wide range of problems, in contrast to a fixed-function quantum computer. A general purpose quantum computer, with emphasis on it’s capacity to handle large problems. If the terms are being used properly, universal emphasizes the ability to perform any operation of a classical computer, again in contrast to a fixed-function quantum computer. See also: large-sized quantum computer.
296. large-scale quantum information network. Quantum communication with a significant number of stations over an extended geographical area.
297. large-sized quantum computer. Vague definition of the usability of a quantum computer in terms of its qubit count. Currently, 50 qubits would be considered a large-sized quantum computer. Less than that would be a medium-sized quantum computer, modest-sized quantum computer, or a small-sized quantum computer. Different individuals and organizations might quibble over these numbers and characterizations. These numbers will rise each year as more qubits become available. In two years, 50 to 100 qubits will likely be considered a medium-sized quantum computer and 128, 192, or 256 qubits would be considered a large-sized quantum computer. In five years, the number for large-sized might be 1024, 2048, 4096, or even 8192, depending on the pace of hardware advances.
298. lattice. A two or three-dimensional regular arrangement of objects of any type, commonly atoms, ions, and molecules. See also: crystal and crystalline structure. See the Wikipedia Lattice (group) article. Alternatively, such an arrangement of larger objects, such as computer systems or processors within a multiprocessor computer system. See also: grid and fabric.
299. lattice problem. TBD. See the Wikipedia Lattice problem article.
300. LC. Initialism for local Clifford.
301. LC equivalence. Short for local Clifford equivalence.
302. LC equivalent. Short for local Clifford equivalent.
303. LC group. Short for local Clifford group.
304. LC operations. Short for local Clifford operations.
305. leaf. See leaf node.
306. leaf node. A node in a graph, especially a tree, which has no relationship to other nodes as subsidiary nodes, in contrast to a branch node. A leaf node is subsidiary to a branch node or the root node.
307. leakage. TBD.
308. leakage error. TBD.
309. learning. The process of acquiring knowledge about a technology, typically through training, reading, and experimentation.
310. leaves. See leaf node.
311. library. See software library.
312. lifting. TBD. Referenced in the A Practical Quantum Instruction Set Architecture paper by Smith, Curtis, and Zeng of Rigetti Computing.
313. light. Electromagnetic radiation which is visible to the unaided human eye. In some contexts, it may also include infrared and ultraviolet. Alternatively, simply a reference to photons.
314. linear algebra. A mathematical framework which is the core mathematics required to model quantum mechanics, and hence quantum computers, including vector spaces and linear combinations that model superposition. Quantum states are modeled with eigenstates, linear combinations of eigenvalues and eigenvectors. Not to be confused with elementary, basic high school algebra. See the Wikipedia Linear algebra article.
315. linear combination. In linear algebra, two or more vectors can be combined into a single vector by adding the vectors, each multiplied by a constant or weight. The vectors are also known as eigenvectors or basis vectors. The weights are also known as the eigenvalues for the eigenvectors. Alternatively, each vector can be decomposed into a linear combination of the basis vectors for the vector space and then the two vectors can be added by adding the two linear combinations of basis vectors, weighted as desired. In quantum mechanics, two or more quantum states (vectors) can be combined into a single quantum state (vector) by adding the quantum states (vectors), each multiplied by a constant or weight. Alternatively, each quantum state can be decomposed into a linear combination of the basis states of the quantum system and then the two quantum states can be added by adding the two linear combinations of basis states, weighted as desired. The weights for a quantum system will be the amplitude or probability amplitude for the basis state or eigenvector. The weight is the eigenvalue for the eigenvector (basis state.) The probability for the basis state is the square of the modulus of the amplitude (probability amplitude) — the sum of the squares of the real part and the imaginary part of the complex number representing the probability amplitude. See also: superposition and eigenvalues and eigenvectors.
316. linear complexity. An algorithm whose computational complexity is proportional to the size of its inputO(n). See also polynomial complexity, exponential complexity, and quadratic speedup.
317. linear ion chain. TBD. Relevant to a trapped-ion quantum computer.
318. linear momentum. Product of the velocity and mass of an object. See the Wikipedia Momentum article. Commonly shortened as momentum. See also: angular momentum.
319. linear optical quantum computing. A theoretical approach to quantum computing based on photons for qubits. Abbreviated as LOQC. See the Wikipedia Linear optical quantum computing article and read the Efficient Linear Optics Quantum Computation paper by Knill, Laflamme, and Milburn. See also: Knill-Laflamme-Milburn quantum computation, KLM quantum computation, and boson sampling.
320. linear optics quantum computation. See linear optical quantum computing.
321. linear space. See vector space.
322. linear vector space. See vector space.
323. linguistic element. One of the elements used to define a language with a grammar. Either a terminal symbol or a non-terminal symbol. The former can be a word, term, token, number, punctuation, or a character sequence. The latter is the name or identifier which identifies a syntax rule in the grammar. See the Wikipedia Backus–Naur form article.
324. liquid. Matter which flows freely. See also: liquid, gas, and plasma.
325. liquid matter. See liquid. See also: solid matter, gaseous matter, and plasma matter.
326. liquid medium. A medium comprised of liquid, in contrast with solid medium, gaseous medium, or plasma medium. See also: liquid matter.
327. list. A data structure representing a sequence of data itemslist items, in order, each having an index, with the first item being at index 0 and the last item being at index n minus 1, where n is the number of items in the list. Alternatively, some systems, software, or programming languages may use indexes in the range of 1 to n. A list may be a fixed length list or a dynamic list. In the case of a dynamic list, there will be special functions to query the current size of the list, to add a new item to the end of the list, to insert an item in the middle of the list, and to remove an item from any position in the list. See also: list item.
328. list item. An item, a data item, in a list or queue. Generally, an object or value. Synonym for element.
329. local Clifford. TBD. Abbreviated as LC. See also: local Clifford group and local Clifford equivalence.
330. local Clifford equivalence. TBD. Shortened as LC equivalence. See local Clifford group.
331. local Clifford equivalent. TBD. Shortened as LC equivalent. See local Clifford group.
332. local Clifford group. TBD. See the An efficient algorithm to recognize local Clifford equivalence of graph states paper by Van den Nest, Dehaene, and De Moor
333. local Clifford operations. TBD. Shortened as LC operations. See local Clifford group.
334. local gradient. TBD.
335. local hidden variables. See local hidden variable theory.
336. local hidden variable theory. An attempt to explain quantum mechanics without the need for probability by presuming that there is additional state, the local hidden variables, which accounts for the apparent probabilities of quantum states. See the Wikipedia Local hidden variable theory article. See also: quantum nonlocality.
337. local simulator. See local quantum simulator.
338. local quantum simulator. A quantum simulator running on the user’s computer. See also: remote quantum simulator.
339. local unitary. TBD. Abbreviated as LU. See also: local unitary equivalence.
340. local unitary equivalence. TBD. Shortened as LU equivalence. See the Local unitary equivalence and entanglement of multipartite pure states paper by Kraus.
341. local unitary equivalent. TBD. See local unitary equivalence.
342. local unitary operations. TBD. See also: local unitary equivalence.
343. logic. May be algorithm, software code, code, or quantum logic. Alternatively, Boolean logic.
344. logic gate. See quantum logic gate. Alternatively, a digital electronic component, such as in a classical computer.
345. logic gate execution. See quantum logic gate execution.
346. logic gate instruction set. See quantum instruction set.
347. logical gate. See logic gate.
348. logical qubit. See quantum logical qubit. An ideal qubit as seen from the perspective of a quantum instruction set architecture, quantum program, programmer, or user, in contrast to a physical qubit in the underlying hardware. Error correction schemes may require multiple physical qubits to implement each logical qubit. See also: quantum logical gate. Synonym for computational qubit.
349. longitudinal coherence time. TBD.
350. LOQC. Initialism for linear optical quantum computing.
351. low-depth quantum circuit. A quantum circuit with only a relatively small gate count. Synonym for short-depth quantum circuit and shallow circuit.
352. low-dimensional quantum system. See lower-dimensional quantum system.
353. low-dimensional system. See lower-dimensional quantum system.
354. low dimensionality. See lower-dimensionality. In contrast to high dimensionality.
355. low-level quantum intermediate representation. See intermediate representation, in contrast to a high-level quantum programming language. Referenced in the A Practical Quantum Instruction Set Architecture paper by Smith, Curtis, and Zeng of Rigetti Computing. Shortened as low-level quantum IR. The QUIL language, as described in that same paper, refers to itself as a low-level quantum IR with classical control.
356. low-level quantum IR. Shorthand for low-level quantum intermediate representation.
357. low-noise quantum computer. TBD. In contrast to noisy intermediate-scale quantum computer. See also: lower noise solid state quantum computer. See the Manufacturing low dissipation superconducting quantum processors paper by Nersisyan, Poletto, Alidoust, Manenti, et al of Rigetti Computing.
358. lower-dimensional quantum system. A quantum system with lower dimensionality. Relative concept, simply to suggest fewer dimensions than a higher-dimensional quantum system. Alternatively, a reference to a two-state quantum system, such as a qubit, or a quantum computer constructed with qubits.
359. lower-dimensional system. See lower-dimensional quantum system.
360. lower dimensionality. A relative concept, simply to suggest fewer dimensions than higher dimensionality. Alternatively, a dimensionality of two.
361. lower noise solid state quantum computer. TBD. In contrast to noisy intermediate-scale quantum computer. See also: low-noise quantum computer. See the Manufacturing low dissipation superconducting quantum processors paper by Nersisyan, Poletto, Alidoust, Manenti, et al of Rigetti Computing.
362. LU. Initialism for local unitary.
363. LU equivalence. Short for local unitary equivalence.
364. LU-equivalence. Short for local unitary equivalence.
365. LU equivalent. Short for local unitary equivalent.
366. LU-equivalent. Short for local unitary equivalent.
367. LU operations. Short for local unitary operations.
368. machine. Synonym for computer, but emphasizing the hardware.
369. machine architecture. Overall architecture and design for a machine or computer. Includes or may specifically refer to the instruction set architecture for the machine, although an instruction set architecture may apply to more than one machine architecture, in whole or in part. For example, two or more machine architectures in a family of machine architectures may have identical instruction set architectures, with the exception of the number of qubits, or additional or less specific hardware features, even though the logic gates (instructions) supported by the instruction set are identical.
370. machine language. See instruction set architecture. The instructions or operations which can be directly executed by a computer, in contrast to the higher-level programming languages which most software developers use to write programs. See also: assembly language, which is commonly used as a synonym.
371. machine language instruction. See instruction. Redundant — instruction always means at the level of machine language, in contrast to operations, expressions, and statements which are at the level of source code for a high-level language.
372. machine learning. See the Wikipedia Machine learning article. See also: artificial intelligence and quantum machine learning.
373. machine learning algorithm. Algorithm focused on machine learning. See also: quantum machine learning algorithm.
374. machine level programming. See machine-level programming.
375. machine-level programming. Coding in assembly language at the level of individual instructions or operations. For a quantum computer, in a quantum assembly language at the level of individual quantum logic gates.
376. machine-specific. Some element of code, data, or machine architecture which applies to a particular type of machine and is not shared by other types of machines.
377. magnetic field. TBD. see the Wikipedia Magnetic field article. See also: electric field and electromagnetic field.
378. magnetic quanta. TBD.
379. magnitude. Size of a quantity or absolute value of a number, independent of sign or direction.
380. main diagonal. See main diagonal of a matrix.
381. main diagonal of a matrix. The entries of a matrix along the diagonal from the upper-left corner, in contrast to the antidiagonal which are entries along the diagonal from the upper right corner. If the matrix is not square, entries on the diagonal which would be outside the matrix will be treated as if they were zero. See the Wikipedia Main diagonal article. See also: diagonal of a matrix.
382. main memory. The primary memory which is used to store data during execution of a computer program. See also: mass storage. At the present, quantum computers have no main memory.
383. main processor. The primary processor on a computer where application programs are executed. There may be secondary processors, auxiliary processors, and coprocessors as well, but they are for use by specialized software rather than for programs developed by users. In a multiprocessor computer system, one of the processors will be the main processor, controlling the overall computer system, and application programs can be executed on any of the other processors in addition to the main processor. See also: central processing unit, multiprocessor, coprocessor, adjunct processor, auxiliary processor, secondary processor, parallel processor, or graphics processor.
384. Majorana. TBD. See also: Majorana-based quantum computer.
385. Majorana-based fermionic quantum computation. TBD. See also: Majorana-based quantum computer.
386. Majorana-based quantum computer. TBD.
387. Majorana bound state. TBD. See also: Majorana-based quantum computer.
388. Majorana fermion. TBD. See also: Majorana-based quantum computer.
389. Majorana fermion bound state. TBD. See also: Majorana-based quantum computer.
390. Majorana mode. TBD. See also: Majorana-based quantum computer.
391. Majorana particle. TBD. See also: Majorana-based quantum computer.
392. Majorana quantum computer. TBD. See also: Majorana-based quantum computer.
393. Majorana quantum computing. TBD. See also: Majorana-based quantum computer.
394. Majorana quasiparticle. TBD. See also: Majorana-based quantum computer.
395. Majorana zero mode. TBD. See also: Majorana-based quantum computer.
396. majorization. TBD.
397. management. Middle-level and senior-level leadership within an organization. Responsible for direction, strategy, decisions, budgeting, and hiring.
398. management approval. The process of getting management to sign off on the concept of an acquisition of a product or service, after a management review. See also: budget approval.
399. management review. The process of management studying and analyzing a proposal for the acquisition of a product or service, to be followed, if successful, by management approval. See also: budget approval.
400. mandatory requirement. A requirement for a system which must be met, in contrast to an optional requirement which is preferred and encouraged, but not strictly mandatory.
401. manifestations of quantum theory. TBD.
402. manufacturing process. The technology and processes needed to produce a system, product, component, or material.
403. many-body localization. TBD. Abbreviated as MBL.
404. many-body quantum systems. TBD. Such as molecules.
405. map. To perform a mapping. Alternatively, a table which maps or transforms from an input value to an output value.
406. mapping. The process of transforming an input value to an output value. Similar to a function but the set of input values is very limited so that a simple table can perform the transformation rather than requiring computation and code. Alternatively, the table itself.
407. mark. A visual indication of some significance, intended to indicate either a location, an entity, or some meaning, generally symbolic. Might be one or more characters, possibly even Greek, or some graphical symbol which is not a character. See also: symbol and symbolic mark.
408. mass. The quality of an object which relates to the degree or extent to which it responds to force or gravity, in contrast to photons which have no mass and are unaffected by force and gravity. See also: matter and massless. Alternatively, simply a characterization of something as being large or plentiful, such as mass storage.
409. mass storage. Memory used to store data that either will not fit in main memory or which will be needed either by another computer program or by a computer program executing at some future time. Generally capable of storing a very large amount of data, generally many times greater than that which will fit in main memory. For a classical computer, disk drives and tape drives were used for this purpose. In more recent years, flash storage (solid-state drive) has become more popular even though having a lesser capacity. At the present, quantum computers have no mass storage.
410. massless. Having no mass.
411. matchcircuit. TBD.
412. matchgate. TBD.
413. material. Quantities of atoms and molecules which can be assembled in forms which allow objects to be constructed. Roughly a synonym for matter, but with emphasis on being in a form which has utility, such as construction materials, rather than the purely abstract, occurring at too small a scale to have utility, or being in a non-solid state (gas, liquid, or plasma.)
414. mathematical. Having some connection to mathematics.
415. mathematical calculation. The use of mathematical operations to calculate some quantity from given values. Shortened as calculation. See also: formula and algebraic calculation.
416. mathematical constant. A value or a symbolic name for the value which has a conceptual significance in mathematics or a scientific field such as physics or quantum mechanics, such as e, pi, i, or h.
417. mathematical formula. An expression of a mathematical calculation, using values and mathematical operations. See also: mathematical function.
418. mathematical framework. A portion of mathematics which defines an approach to a modeling and working with a significant set of problems.
419. mathematical function. A mapping of any number of input values to an output value, from a domain to a range. In a programming language the mapping is performed by code. See the Wikipedia Function (mathematics) article. See also: domain of a function and range of a function.
420. mathematical matrix. See matrix.
421. mathematical operation. Any operation used in a mathematical formula, including addition, subtraction, multiplication, division, square root, exponential, and modulus or remainder, producing a real value, complex value or an integer value. The operands of a mathematical operation can be values, variables, special values such as e and pi, functions, or parenthesized mathematical formulas. See also: mathematical formula and algebraic expression.
422. mathematics. The study, theory, concepts, and practice of numbers, shapes, calculation, structure, space, symbols, relationships, and logic, as distinct from the actual real world, science, and applications of those concepts. See the Wikipedia Mathematics article.
423. matrix. A mathematical framework used to represent operators in quantum mechanics. See the Wikipedia Matrix (mathematics) article. See also: column matrix, column vector, row matrix, row vector, bra, ket, unitary matrix. Alternatively, any two-dimensional or tabular format of model or presentation of data or information.
424. matrix product state (MPS) tomography. See matrix product state tomography.
425. matrix product state tomography. TBD. See the Efficient tomography of a quantum many-body system paper by Lanyon, Maier, et al. Abbreviated as MPS tomography.
426. matter. Physical bodies, material, and particles which have mass, in contrast to photons which have no mass. May be in a solid, liquid, gas, or plasma state.
427. maximally entangled basis. TBD.
428. maximally entangled state. TBD.
429. maximally entangled two-qubit states. TBD.
430. maximally entangling XX gate. TBD.
431. maximum coherent depth. The quantum circuit depth after which quantum coherence declines to an unacceptable degree. Approximately the ratio of the coherence time T2 over the gate time.
432. MBL. Initialism for many-body localization.
433. McWeeny purification. TBD.
434. measurable quality. A quality of a system which can be measured. See also: observable quality and detectable quality. See also: measurable quantity.
435. measurable quantity. A quantity of a system which can be measured. See also: observable quantity and detectable quantity. See also: measurable quality.
436. measure. An attempt to observe or measure the quantum state of a quantum system or qubit. See measurement. See also: observe, final results, and collapse of wave function.
437. measure of coherence. TBD.
438. measurement. See quantum measurement. Synonym for readout. See also: intermediate measurement.
439. measurement in the computational basis. TBD. See also: computational basis.
440. measurement in the standard basis. TBD.
441. measurement logic gate. See quantum measurement logic gate.
442. measurement noise. TBD.
443. measurement phase. See quantum measurement phase.
444. measured state. The quantum state of one or more qubits, as captured by quantum measurement.
445. the measurement problem. The fact that the act of capturing the quantum state of a qubit via measurement returns only a single real eigenvalue of the quantum state and causes the quantum state of that qubit to collapse, causing the rest of the quantum state to be lost.
446. measurement results. The collection of individual results or measurements of the quantum states of the qubits of interest upon completion of execution of a quantum logic circuit or quantum program. The results, collectively. May simply be referred to as the measurements.
447. mechanical. Relating to motion and mechanical force.
448. mechanical force. Any force which causes or results in a motion, mechanical pressure, or mechanical stress.
449. mechanical movement. A change in the position of a material or object as the result of the application of mechanical force. Synonym for motion.
450. mechanical pressure. A detectable or measurable degree of mechanical force on a material. Commonly compression.
451. mechanical stress. See mechanical pressure. May be compression, tension, or shear. May lead to mechanical strain.
452. mechanical strain. A detectable or measurable degree of compression, expansion, or deformation of a material due to mechanical stress.
453. mechanical wave. A wave propagated through a medium (solid, liquid, gaseous, or plasma, but not a vacuum) as a result of mechanical pressure. See also: sound.
454. mechanics. The branch of physics concerned with motion and behavior of physical bodies under the influence of forces and interactions with other physical bodies. Subfields include classical mechanics (Newtonian mechanics), quantum mechanics, and statistical mechanics (e.g., thermodynamics.) See the Wikipedia Mechanics article.
455. medium. Any material or state of matter capable of transmitting either matter or energy, including heat, sound, and electromagnetic radiation. See also: solid medium, liquid medium, gaseous medium, or plasma medium. [TBD: does a vacuum constitute a medium even though it has no matter, but can transmit both matter and energy?].
456. medium-sized quantum computer. Vague definition of the usability of a quantum computer in terms of its qubit count. Currently, 20 qubits would be considered a medium-sized quantum computer. Less than that would be a modest-sized quantum computer or a small-sized quantum computer. Currently, 50 or more qubits would be considered a large-sized quantum computer. Different individuals and organizations might quibble over these numbers and characterizations. These numbers will rise each year as more qubits become available. In two years, 50 to 100 qubits will likely be considered a medium-sized quantum computer and 128, 192, or 256 qubits would be considered a large-sized quantum computer. In five years, the number for medium-sized might be 512, 1024, 2048, 4096, or even 8192, depending on the pace of hardware advances.
457. member. Belong to a group.
458. membership. See member.
459. memory. Storage for data which can be accessed very rapidly, in contrast to mass storage. Generally a synonym for main memory, although classical computers have a variety of forms of memory.
460. message. Any amount of information which is to be transmitted between two locations — from a sender to a recipient, which may be people or processes (computer programs.) It may consist of readable, natural language text, such as an email or social media message, or arbitrary technical symbols, raw data, or binary data, including executable programs. See also: cryptographic message and interprocess communication
461. method. Generally a synonym for algorithm. May be a rather informal process, while an algorithm will generally be rather formal. Generally, a process for achieving a goal.
462. millikelvin. One-thousandth (1/1,000) of a degree kelvin (K). Ultra-cold temperature only a small fraction of a single degree above absolute zero. See the Wikipedia Orders of magnitude (temperature) article. Abbreviated as mK.
463. microcode. See firmware. Specialized code within a processor which is used to implement some or all of the functions or instructions of the processor.
464. microwave. High frequency short wavelength radio waves (electromagnetic radiation) which travel in a straight line. Higher frequency than normal radio waves and lower frequency than visible light or infrared. In the context of quantum computing they can be used to control qubits. See the Wikipedia Microwave article. See also: microwave circulator, microwave pulse, and microwave signal.
465. microwave circulator. A device for controlling the flow of a microwave signal. See the Wikipedia Circulator article. In a quantum computer this is referred to as a quantum circulator. See the Physics Synopsis: Quantum Circulators Simplified article (synopsys.) Microwaves are used to control qubits, so careful control of the flow of microwaves is needed to minimize quantum decoherence.
466. microwave drive. TBD. Use of microwaves to control a qubit, commonly with a resonator, such as for execution of a quantum logic gate. See also: resonator port and flux bias line. Referenced in The Quantum Processing Unit (QPU) doc from Rigetti Computing.
467. microwave pulse. A microwave signal of very short duration. Technique for controlling or manipulating the quantum state of a quantum system (even a single qubit) using an external microwave source. See also: coherent control. See the IBM Q FAQ.
468. microwave signal. See microwave or microwave pulse.
469. middleware. See middleware software.
470. middleware software. Software libraries, software frameworks, and software services which provide a foundation for development of application software. This includes database software. It is positioned in the middle, between the operating system and application software.
471. minimal quantum latency. TBD.
472. minimally connected. See minimally entangled.
473. minimally entangled. Only at most a few possible pairs of qubits of a quantum computer may be entangled simultaneously, in contrast to fully entangled, where all possible pairs of qubits may be entangled, highly entangled where most pairs of qubits are entangled, or partially entangled, where more than a few but not all possible pairs of qubits may be entangled at the same time.
474. mitigate. See mitigation.
475. mitigation. Capability of modifying conditions to counteract some event or conditions which have been detected, to make it appear as if they hadn’t occurred. Such as errorserror detection and error correction. See also: detection and compensation.
476. mitigation of errors. See quantum error correction. See also: mitigation.
477. mixed state. A quantum state which is a superposition of the two basis states, |0> and |1>. This reduces the amplitude (probability amplitude) of each of the complex vectors representing the basis states, such that the squares of the modulus (magnitude) for each amplitude sum to 1.0 as required for unitarity. Since the modulus for each complex vector is no longer 1.0, the complex vectors are inside of the Bloch sphere rather than on its surface. In contrast to pure state which is either a basis state or a rotation of a basis state, so that the modulus of the amplitude of the basis vector is 1.0, putting it on the surface of the Bloch sphere, rather than on the interior as for a mixed state. [TBD: verify] See the Wikipedia Quantum state article.
478. mixed state entanglement. TBD.
479. mK. Initialism for millikelvin.
480. modest-sized quantum computer. Vague term which could refer to a quantum computer which: 1) has a relatively small number of qubits, 2) has more than a relatively small number of qubits, 3) has more than a few qubits but not a lot of qubits, a dozen of so, in the range of 8 to 16, or 4) is relatively small in size, closer to a smartphone or desktop computer, or at least no bigger than a filing cabinet, compared to room-size quantum computers of 2018. See also: small-sized quantum computer, medium-sized quantum computer, and large-sized quantum computer..
481. mod function. See modulo operation.
482. modular exponentiation. TBD.
483. modular multiplication. TBD. Referenced in the Circuit for Shor’s algorithm using 2n+3 qubits paper by Beauregard.
484. modulo operation. The remainder after performing an integer division between two numbers (integer or real.) See the Wikipedia Modulo operation article.
485. modulus. See absolute value. Alternatively, the modulo operation for integer and real numbers.
486. molecule. Two or more atoms which have formed one or more chemical bonds which cause them to persist in close physical proximity and to act as an integrated unit. The atoms may or may not be of the same element.
487. Mølmer-Sørensen gate. TBD.
488. Molmer-Sorensen gate. See Mølmer-Sørensen gate.
489. Mølmer-Sørenson interaction. TBD.
490. Molmer-Sorensen interaction. See Mølmer-Sørensen interaction.
491. Mølmer-Sørensen XX entangling gate. TBD.
492. Molmer-Sorensen XX entangling gate. See Mølmer-Sørensen XX entangling gate.
493. Mølmer-Sørensen XX gate. TBD.
494. Molmer-Sorensen XX gate. See Mølmer-Sørensen XX gate.
495. moment of time. A particular point in time. May be either a discrete moment of time or part of a continuous period of time.
496. moments of time. Two or more discrete points in time, or all of the moments during some continuous period of time.
497. momentum. See linear momentum.
498. monogamy of entanglement. TBD.
499. Moore’s Law. Proposition that the density of transistors on an integrated circuit will double every two years. May now have slowed down to doubling every two and a half to three years. A continued deceleration is a negative for classical computers and an argument in favor of quantum computing. See the Wikipedia Moore’s Law article. See also: post-Moore’s Law era.
500. motion. Mechanical movement. See also: mechanical force.
501. motional modes of the linear ion chain. TBD. relevant to a trapped-ion quantum computer.
502. MPS. Initialism for matrix product state. See also: MPS tomography and matrix product state tomography.
503. MPS tomography. Abbreviation for matrix product state tomography.
504. multi-byte character code. For character codes in Unicode which do not fit in a single 8-bit byte, Unicode defines several methods for representing those larger values as multiple bytes, most notably UTF and UTF-8. See the Wikipedia Unicode article, specificialy the Unicode Transformation Format and Universal Coded Character Set section. See also: UTF-8, UTF-16 and UTF-32.
505. multi-degree-of-freedom multiplexed solid-state quantum memory. TBD. Referenced in the Researchers achieve multifunctional solid-state quantum memory article. Shortened as multiple-DOF memory.
506. multipartite entanglement. Quantum entanglement of of three or more qubits, in contrast to bipartite entanglement which is limited to only a pair of qubits. Alternatively, the quality of a quantum computer of supporting entanglement of three or more qubits in a particular entanglement at a time. Although multipartite entanglement does cover the case of exactly three qubits in a single entanglement, the term tripartite entanglement refers specifically to the case of entanglement of exactly three qubits. At present, here in August 2018, current quantum computers support only bipartite entanglement, no more than pairs of qubits. [TBD: Whether or to what extent simulators support multipartite entanglement]. Quantum communication has a more pressing need for multipartite entanglement. See the Wikipedia Multipartite entanglement article and the Bipartite entanglement in AJL’s algorithm for three-strand braids paper by Qu, Dong, Wang, Bao, Song, and Song. see also: bipartite entanglement and tripartite entanglement.
507. multiple-DOF memory. Short for multi-degree-of-freedom multiplexed solid-state quantum memory.
508. multiple-DOF memory with high multimode capacity. TBD. Referenced in the Researchers achieve multifunctional solid-state quantum memory article. See multi-degree-of-freedom multiplexed solid-state quantum memory.
509. multiple inheritance. In object-oriented programming (OOP), an OOP class can be derived from more than one parent class, meaning that it inherits access to the data items and functions of all of its parent classes.
510. multiplexed quantum repeater. TBD. Referenced in the Researchers achieve multifunctional solid-state quantum memory article.
511. multiprocessor. See multiprocessor computer system.
512. multiprocessor computer system. A computer system with more than one processor. This can be any combination of secondary processors and parallel processors. Generally, it’s not the secondary processors (such as coprocessors or GPUs) which make it a multiprocessor system, but the parallel processors, each of which is capable of executing a full program for a user, in contrast to the specialized software which executes on a secondary processor. See also: main processor, coprocessor, adjunct processor, auxiliary processor, secondary processor, parallel processor, or graphics processor.
513. multiprocessor system. See multiprocessor computer system.
514. multistate, contracted variational quantum eigensolver. TBD. Abbreviated as multistate, contracted VQE or MC-VQE.
515. multistate, contracted VQE. Abbreviation for multistate, contracted variational quantum eigensolver.
516. mutually orthogonal entangled states. TBD.
517. n. Generally the count of values in some set or collection of values or data structure.
518. n-bit value. Any value on a classical computer which is represented as n contiguous bits, which can represent only a single value out of a range of 2 to the n distinct values, in contrast to an n-qubit quantum value, which can represent any or all 2 to the n values simultaneously.
519. n-qubit Clifford operation. A Clifford operation which operates on n qubits. A sequence of one or more quantum logic gates operating on n qubits whose effect on the quantum state of those qubits can be expressed as a sequence of Clifford gates. TBD. Referenced in the Classical simulation complexity of extended Clifford circuits paper by Jozsa and Van den Nest.
520. n-qubit quantum register. A sequence of n qubits considered as a single unit. Comparable to a register of a classical computer. Or, comparable to an n-bit value of a classical computer. Except that an n-qubit quantum register can hold 2 to the n quantum states simultaneously.
521. n-qubit value. See n-qubit quantum value.
522. n-qubit quantum value. The collection of values represented in a collection of n qubits, which can be any number of values up to and including 2 to the n values, using quantum superposition, in contrast to an n-bit value of a classical computer which can represent only a single value out of 2 to the n possible values.
523. N-representability. TBD.
524. N-representability conditions. TBD.
525. N-representable manifold. TBD.
526. name. See identifier and label, in contrast to a word from a dictionary, a number, or a symbol. Technically, a name could be a word or a number, or possibly even a symbol, but it would function as an identifier of label rather than have the usual meaning of a word, number, or symbol. May be a proper name.
527. narrow-band quantum Fourier transform. A banded quantum Fourier transform where the m or b bandwidth parameter is relatively small compared to the total number of bits in the input number, commonly 8 qubits. Transform entries which are very small will be discarded since they will have very little impact on the final results but consume a lot of computational resources. In contrast to a full quantum Fourier transform.
528. narrow-purpose. See narrow purpose.
529. narrow purpose. Suitable only for a relatively narrow range of uses, limiting application, in contrast to the even narrower range of use of fixed purpose, or the wide range of uses of general purpose.
530. nascent technology. A technology which is relatively new and unproven.
531. National Quantum Coordination Office. TBD. Referenced in National Quantum Initiative Act bill.
532. National Quantum Initiative. A proposal in 2018 for the U.S. government to fund research in quantum information science for ten years. See SST Committee Approves the National Quantum Initiative Act press release and text of National Quantum Initiative Act bill.
533. National Quantum Initiative Act. See National Quantum Initiative and text of National Quantum Initiative Act bill.
534. National Quantum Initiative Advisory Committee. See National Quantum Initiative. Referenced in National Quantum Initiative Act bill.
535. National Quantum Initiative Program. See National Quantum Initiative. Referenced in National Quantum Initiative Act bill.
536. natural language. A language used by people, homo sapiens. Both spoken and written.
537. natural language word. A representation of a word from a natural language as text, simply the literal characters.
538. natural language text. Text which is a sequence of natural language words and punctuation rather than simply a raw sequence of characters.
539. nanoscale thermodynamics. TBD.
540. near-term device. See near-term quantum computer. Technically, a device could be any type of computer, including a classical computer, but in the context of quantum computing it is safe to presume that it is a reference to a quantum computer, but it could also be a reference to a single qubit, or a chip within a quantum computer.
541. near-term intermediate scale quantum. See near-term intermediate-scale quantum.
542. near-term intermediate-scale quantum. See near-term intermediate-scale quantum computer.
543. near-term intermediate scale quantum computer. See near-term intermediate-scale quantum computer.
544. near-term intermediate scale quantum computer. See near-term intermediate-scale quantum computer.
545. near-term intermediate-scale quantum computer. See noisy intermediate-scale quantum computer.
546. near-term intermediate scale quantum device. See near-term intermediate-scale quantum device.
547. near-term intermediate-scale quantum device. See noisy intermediate-scale quantum device.
548. near-term quantum computer. Quantum computer designs for which quantum computers are available today, off the shelf, for actual use by real developers. Commonly a reference to near-term intermediate-scale quantum computer or noisy intermediate-scale quantum computer. Alternatively, limited to commercial availability, excluding machines which are only operating in research labs. Alternatively, includes machines which are operating in research labs. Alternatively, includes designs which are expected to be built in the near term, the next few months to a year or so. But excludes designs which are not expected to be built for more than a year or so. See also: current quantum computer and future quantum computer.
549. near-term quantum device. See near-term quantum computer.
550. near-term quantum processor. See near-term quantum computer.
551. nearest-neighbor matchgate. TBD.
552. neighboring qubits. Qubits which are capable of being coupled (entangled). This typically means that they are physically adjacent on a quantum chip, but that is not an absolute requirement. The key requirement is that there be an interconnection between the qubits, such as a resonator which permits coupling to be initiated.
553. net charge. See net electric charge.
554. net electric charge. The exact degree of imbalance between the number of protons and the number of electrons of an ion or charged particle. The number of protons minus the number of electrons. +1 means a deficit of one electron. -2 means a surplus of two electrons. See also balance of charge.
555. net negative charge. The quality of an ion or charged particle having a net surplus of electrons — more electrons than protons. The exact number of the surplus of electrons. See also: net electric charge.
556. net positive charge. The quality of an ion or charged particle having a net deficit of electrons — fewer electrons than protons. The exact number of the deficit of electrons. See also: net electric charge.
557. network. Two or more computer systems which are connected. Also known as nodes. The connection may be physical, such as with cabling, wirelessly, or over a communication network. They may be in relatively close proximity, a local area network, or be widely dispersed, a wide area network. Whether near or far, the systems can constitute the Internet if they use standard Internet protocols for communication. Alternatively, synonym for a graph in graph theory.
558. networking quantum computers. See quantum network.
559. neural network. TBD. See the Wikipedia Neural network and Artificial neural network articles. See also: quantum neural network (QNN) and artificial intelligence.
560. Newtonian mechanics. The subfield of physics, mechanics, associated with the motion and interactions of macroscopic physical bodies, larger than atoms but traveling much slower than the speed of light. The world of everyday objects, machinery, vehicles, billiard balls, planets, moons, satellites, stars, and galaxies. In contrast to quantum mechanics, which is associated with motion and interactions at the atomic and subatomic level, where the distinction between particles and waves overlaps and is more about probability than certainty and determinism. Synonym for classical mechanics.
561. next quantum revolution. Vague hyperbole for any upcoming major advances in the field of quantum computing. See the NSF The Quantum Leap: Leading the Next Quantum Revolution web page. See also: quantum revolution.
562. nibble. On a classical computer, may be interpreted either as a 4-bit integer or as simply four bits. Alternatively half a byte. Alternatively a hexadecimal digit.
563. niche application. An application category which is relatively narrow and specialized. Alternatively, any application, in the sense that that is what applications are all about — each of them focuses on a particular niche, in contrast to being truly general-purpose.
564. niobium. A metallic element which becomes a superconductor below 9.2 K. Used to create a superconducting loop which in conjunction with a Josephson junction is used to construct a qubit, such as a superconducting transmon qubit. See the Wikipedia Niobium article.
565. NISQ. Initialism for noisy intermediate-scale quantum or noisy intermediate-scale quantum device. Refers to noisy intermediate scale quantum computer. Some interpret it as noisy intermediate stage quantum — scale vs. stage. Alternatively, initialism for near-term intermediate-scale quantum, near-term intermediate-scale quantum computer, or near-term intermediate-scale quantum device. Current quantum computers and near-term quantum computers which have a moderate number of qubits (10 to 128 or so) supporting a moderate circuit depth of quantum logic gates (20 to 100 or so) which are fairly reliable but not fault-tolerant per se.
566. NISQ algorithm. Algorithm which has been designed and optimized to exploit noisy intermediate scale quantum computers (NISQ computer or NISQ for short) — current quantum computers and near-term quantum computers, which have a moderate number of qubits (50 to 100) supporting a moderate circuit depth of quantum logic gates (40 to 50 or so) which are fairly reliable but not fault-tolerant per se.
567. NISQ chemistry. TBD.
568. NISQ chemistry computation. TBD.
569. NISQ computer. See noisy intermediate scale quantum computer. Quantum computer based on noisy intermediate scale quantum technology.
570. NISQ device. Short for noisy intermediate-scale quantum device. Generally NISQ computer.
571. NISQ era. The stage of the quantum computing market when NISQ computers are common. The stage that we are on the verge of entering, as of July 2018.
572. nitrogen-vacancy center. Exploiting the physics of defects in diamonds for construction of qubits. Also referred to as diamond vacancy. See the Wikipedia Nitrogen-vacancy center article.
573. NMR. Initialism for nuclear magnetic resonance.
574. NMR quantum computer. See nuclear magnetic resonance quantum computer.
575. no-cloning theorem. A quantum circuit or quantum algorithm cannot make an exact copy of the full quantum state of another qubit, since that would be comparable to measuring the qubit which would cause its wave function to collapse. Instead, quantum algorithms utilize quantum entanglement, such as with the controlled-NOT gate. See the Wikipedia No-cloning theorem article.
576. no net charge. An atom with a balance of charge — the count of protons is the same as the count of electrons. The quality of an insulator.
577. node. A representation of data in a graph, in graph theory. Alternatively, a computer system in a network. A network is a graph.
578. noise. See quantum noise.
579. noise model. Parameters for simulated noise so that a quantum simulator can produce results more closely aligned with those of a real quantum computer. Otherwise, a quantum simulation executed on a classical computer would tend to be deterministic rather than probabilistic. The noise model needs to be tuned to reflect the behavior of a particular design of quantum computer and architecture.
580. noisy. Execution of quantum logic gates is prone to quantum errors due to either quantum decoherence or environmental factors.
581. noisy intermediate-scale quantum. See noisy intermediate scale quantum technology. Abbreviated as NISQ.
582. noisy intermediate scale quantum computer. See noisy intermediate-scale quantum computer.
583. noisy intermediate-scale quantum computer. Quantum computer based on noisy intermediate scale quantum technology. Shortened as NISQ computer.
584. noisy intermediate scale quantum device. See noisy intermediate-scale quantum device.
585. noisy intermediate-scale quantum device. Generally a noisy intermediate-scale quantum computer. Abbreviated as NISQ device or simply NISQ.
586. noisy intermediate scale quantum technology. See noisy intermediate-scale quantum technology.
587. noisy intermediate-scale quantum technology. Quantum circuits with an intermediate number of qubits (10 to 128 or so) and an intermediate circuit depth of quantum logic gates (10 to 100 or so) will be somewhat noisy but not so noisy that the results are completely unusable, and will be reasonably satisfactory for some applications. Smaller circuits may not encounter significant quantum errors, and larger circuits may encounter too many quantum errors for the results to be usable See the Quantum Computing in the NISQ era and beyond paper by John Preskill. Abbreviated as NISQ. See also: NISQ computer and noisy intermediate scale quantum computer.
588. noisy intermediate stage quantum. See noisy intermediate-scale quantum.
589. noisy physical gate. A quantum logic gate applied to a quantum physical qubit which causes a quantum error, even if quantum error correction (QEC) is able to correct the error using other quantum physical qubits, which collectively comprise a quantum logical qubit. See the Optimizing the Frequency of Quantum Error Correction using the [[7,1,3]] Steane Code paper by Abu-Nada, Fortescue, and Byrd.
590. noisy quantum computer. A quantum computer constructed with noisy qubits — they do not have quantum error correction (QEC), so that they are prone to a non-trivial quantum error rate.
591. noisy quantum device. See noisy quantum computer. Alternatively, a noisy qubit.
592. noisy quantum hardware. TBD.
593. noisy qubit. A qubit which is noisy — it does not have quantum error correction (QEC), so that it is prone to a non-trivial quantum error rate.
594. non-adiabaticity. TBD.
595. non-adaptive Clifford circuit. A Clifford circuit in which operations are fixed and will not vary in response to any intermediate measurements, in contrast to a non-adaptive Clifford circuit in which the operations may be chosen based on intermediate measurements of the outcomes of previous operations. TBD. Referenced in the Classical simulation complexity of extended Clifford circuits paper by Jozsa and Van den Nest.
596. non-clifford gate. A quantum logic gate whose effect on the quantum state of a qubit cannot be expressed as a sequence of basic Clifford gates. TBD. Referenced in the Classical simulation complexity of extended Clifford circuits paper by Jozsa and Van den Nest.
597. non-clifford operation. A sequence of one or more quantum logic gates whose effect on the quantum state of a qubit cannot be expressed as a sequence of basic Clifford gates. TBD. Referenced in the Classical simulation complexity of extended Clifford circuits paper by Jozsa and Van den Nest.
598. non-computable function. TBD. In contrast to a computable function.
599. non-executable statement. A statement in a high-level programming language which will not perform any action when the program is executing, such as a declaration, in contrast to an executable statement. It is possible that a non-executable statement could cause some action, such as evaluating an expression to initialize a variable.
600. non-nearest-neighbor matchgate. TBD.
601. non-numeric. See non-numeric value.
602. non-numeric value. Data which is not in the form of a numeric value — real number, complex number, or integer number. This can include boolean values, characters, text or strings, composite values such as pairs or lists of values, or user-defined values. Whether a rational number, expressed by a numerator and denominator which are integers should be considered a numeric value or a non-numeric value is unclear and debatable — it works both ways.
603. non-numeric data. See non-numeric value.
604. non-planar quantum integrated circuit. Quantum integrated circuit based on a non-planar quantum integrated circuit architecture.
605. non-planar quantum integrated circuit architecture. An architecture for quantum integrated circuits utilizing three-dimensional cavities for resonators. See the Superconducting Caps for Quantum Integrated Circuits paper by O’Brien, Vahidpour, Whyland, Angeles, Marshall, Scarabelli, Crossman, Yadav, Mohan, Bui, Rawat, Renzas, Vodrahalli, Bestwick, and Rigetti.
606. non-quantum hardware. Hardware whose function is focused on processing of digital signals or analog signals, in contrast to quantum hardware whose function is focused on processing of quantum states. The hardware of a quantum computer outside of the qubits, including quantum control.
607. non-real. A number which is not a real number. An imaginary number. The imaginary part of a complex number. Alternatively, a non-numeric.
608. nonadiabatic and non-abelian holonomic quantum gates. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka.
609. nondeterministic. A system, process, algorithm, or code which is not governed by determinism — the starting conditions do not completely determine the final results. In contrast to deterministic.
610. nondeterministic polynomial time. TBD. Abbreviated as NP. See also: polynomial time.
611. nondeterministic result. The uncertainty and probabilistic nature of results on a quantum computer which tends to make them at least somewhat nondeterministic, in contrast to the certainty and deterministic nature of results on a classical computer. See also: deterministic result.
612. nonlocal property. See quantum nonlocality.
613. nonlocality. See quantum nonlocality.
614. nontrivial circuit. A quantum logic circuit with more than simply a very few quantum logic gates. See also: trivial circuit.
615. NP. Initialism for nondeterministic polynomial time. See also: P.
616. nuclear magnetic resonance. Shortened as NMR.
617. nuclear magnetic resonance quantum computer. A quantum computer which utilizes molecules for qubits, using nuclear magnetic resonance (NMR) to control the spin state of atoms in the molecule. See the Wikipedia Nuclear magnetic resonance quantum computer article. See the Quantum Computing and Nuclear Magnetic Resonance paper by J. A. Jones.
618. number. A symbol for a value (numeric value) which is a count, measure, or simply a label. See the Wikipedia Number article. The meaning is clear on a classical computer, but not so clear on a quantum computer, which has only quantum states, such that measuring a qubit will return a binary 0 or 1.
619. numeric. The quality of numbers and numeric values, including absolute numbers and differences or distances between numbers. Alternatively, text or a character string which is in fact a representation of a number. See numeric value.
620. numeric value. A real value, complex value, or integer value. See also: non-numeric value and rational number.
621. numerical. See numeric.
622. numerical calculation. See numerical computation.
623. numerical computation. Computation with algebraic calculations with an emphasis on obtaining numerical results.
624. numerical gradient. TBD. In contrast to an analytical gradient.
625. numerical results. The results of numerical computation which produce some set of real values, complex values, and integer values.
626. OAM. Initialism for orbital angular momentum.
627. OAM states. Short for orbital-angular-momentum states.
628. object. A localized thing, hardware, physical system, software, or data, which might be referenced, acted upon, or act on other objects. It may or may not have a type. It may or may not have a name. See also: entity. Alternatively, the basic unit of structured information in the object-oriented programming (OOP) paradigm of design and coding.
629. objective. Synonym for goal. Alternatively, the objective value for an objective function for given input values.
630. objective function. A mathematical function which an algorithm seeks to minimize, maximize, or otherwise optimize. See quantum annealing. See the Wikipedia Mathematical optimization article and the D-Wave Programming with D-Wave: Map Coloring Problem whitepaper. See also: objective value and objective.
631. objective value. Value of the objective function for given input values. Shortened as objective.
632. object-oriented programming. A paradigm or approach to organizing code and data structures based on the definition of a hierarchy of classes of objects, each of which has a well-defined set of functions which operate only on objects of that class or its subclasses. Abbreviated as OOP. No obvious way that this would fit into the quantum world at this time. But the question remains how algorithms and code based on the OOP paradigm can be migrated to the quantum world. See the Wikipedia Object-oriented programming article. See also: OOP object and OOP class.
633. oblivious amplitude amplification. TBD.
634. observe. Same as measure. An attempt to observe or measure the quantum state of a quantum system or qubit. See measurement. See also: final results. See also: collapse of wave function.
635. observable. A physical quantity of a system which can be observed or measured, such as the two quantum states of a qubit. In quantum mechanics an observable is an operator, which yields a basis state corresponding to an eigenvector based on the probability that the quantum system is in that quantum state, a basis state, which is a basis vector. The probability is the square of the modulus of the eigenvalue associated with that eigenvector. The eigenvalue is a complex number representing the amplitude (probability amplitude) for that eigenvector. The basis states for current quantum computers are |0> and |1>. Each qubit will have those two basis states as observables and their associated eigenvectors and associated eigenvalues. The wave function for a quantum system is the sum or linear combination of all of the eigenvectors of the observables and their eigenvalues. That linear combination permits superposition of more than one eigenvector (basis state.) Current quantum computers commonly have a pair of observables for each qubit, which are the two spin states. See the Wikipedia Observable article. See also: quantum operator.
636. observable and measurable quality. A quality of a system which can be observed and measured. See also: observable quality, measurable quality and detectable quality. See also: observable and measurable quantity and observable or measurable quantity.
637. observable and measurable quantity. A quantity of a system which can be observed and measured. See also: observable quantity, measurable quantity and detectable quantity. See also: observable and measurable quality and observable or measurable quantity.
638. observable or measurable quality. A quality of a system which can be observed or measured. See also: observable quality, measurable quality and detectable quality. See also: observable and measurable quantity and observable and measurable quality.
639. observable or measurable quantity. A quantity of a system which can be observed or measured. See also: observable quantity, measurable quantity and detectable quantity. See also: observable and measurable quality and observable and measurable quantity.
640. observable quality. A quality of a system which can be observed. See also: measurable quality and detectable quality. See also: observable quantity.
641. observable quantity. A quantity of a system which can be observed. See also: measurable quantity and detectable quantity. See also: observable quality.
642. observation. See observe.
643. on-chip quantum photonic processor. A quantum photonic processor completely contained on a single integrated circuit, including the qubit itself.
644. one-dimensional Fermi-Hubbard model. TBD. Abbreviated 1D FHM.
645. one-particle reduced density matrix. TBD. Abbreviated as 1-RDM.
646. one-qubit gate. See one-qubit quantum logic gate. Abbreviated as 1Q gate or 1Q. Synonym for single-qubit gate.
647. one-qubit logic gate. See one-qubit quantum logic gate. Abbreviated as 1Q gate or 1Q. Synonym for single-qubit logic gate.
648. one-qubit quantum logic gate. A quantum logic gate which operates on only a single qubit. Abbreviated as 1Q gate or 1Q. Synonym for single-qubit gate, one-qubit logic gate, and one-qubit gate. See also: two-qubit quantum logic gate.
649. one state. The quantum state of a qubit is |1>, equivalent to a binary value of 1, in contrast to the zero state, which is equivalent to a binary value of 0. Note that a qubit can be in both the zero state and one state at the same time due to superposition.
650. ongoing evolution of quantum computing. Progress is being made on every front of quantum computing on a fairly frequent basis, including theory, foundation technology, research, hardware technology, system construction, commercial offerings, software tools, applications, and adoption for use.
651. OOP. Initialism for object-oriented programming.
652. OOP class. The definition of a class for a type of object according to the object-oriented programming (OOP) paradigm by which each object in the class has a defined set of data items as well as a defined set of functions which operate on those data items. A hierarchy of classes may be defined such that subclasses of a class may use data items and functions of both that parent class and any of its superclasses. See the Wikipedia Object-oriented programming article.
653. OOP object. An object of a class in object-oriented programming. See also: OOP class.
654. OpenQASM. Short name for Open Quantum Assembly Language. Alternatively, OPENQASM.
655. Open Quantum Assembly Language. A quantum assembly language offered as part of the IBM Q Experience. See the Open Quantum Assembly Language paper. See the IBM QISKit OPENQASM web page. See the QISKit/openqasm Github repository for both code and specifications.
656. open quantum system. TBD. See the Wikipedia Open quantum system article. See also: quantum bath.
657. operand. An argument for an operator or function. In a high-level programming language this can be a data value or an algebraic expression.
658. operate beyond the supremacy regime. TBD.
659. operating system. Special software on a computer system which is responsible for managing system resources and scheduling processes for execution. Application software typically requires some significant degree of middleware software and software tools rather than running directly on the bare operating system. This concept is primarily for classical computers, including the classical computer which directly controls a quantum computer, but the quantum computer itself has no built-in software and certainly no operating system, just raw hardware. See also: system software and system utilities.
660. operation. See quantum logic operation. In classic computing, an operator and its operands or arguments. Alternatively, the activity and functioning of a system, device, computer, or organization.
661. operational connection. TBD.
662. operational resource. TBD.
663. operational quantum hardware. An existing quantum computer, in contrast to a future quantum computer. A quantum computer which has actually been built, in contrast to a quantum computer which is planned or only theorized.
664. operator. In classical computation, an operator is a function of one or more operands, such as the plus operator (+) which adds two numbers. In quantum mechanics, an operator corresponds to an observable — see observable and quantum operator.
665. opinionated quantum instruction language. Term used by Rigetti Computing for their Quantum Instruction Language (Quil) to indicate their expectation that the near-term usage of quantum computers will be as a coprocessor for a classical computer. Referenced in The Quantum Virtual Machine (QVM) doc from Rigetti Computing.
666. opportunity. A situation which can be exploited to attain a more advantageous situation by applying a solution. See also problem.
667. optical. Relating to visible light. May or may not include infrared light and ultraviolet light.
668. optical crosstalk. TBD.
669. optical fiber. See optical fiber cable.
670. optical fiber cable. A cable capable of transmitting and receiving signals (data) using visible light. See the Wikipedia Optical fiber cable article. Synonym for fiber optic cable.
671. optical quantum computer. TBD. See linear optical quantum computing.
672. optimal solution. See exact solution. See also: approximate solution and practical solution.
673. optimization. The process of designing an algorithm or code so as to make the most effective use of system resources, such as to minimize circuit depth, minimize use of the processor, or minimize use of memory (or qubits). Alternatively, an optimization problem.
674. optimization problem. An application which seeks to optimize the use of resources in the real-world. See quantum annealing.
675. optional requirement. A requirement for a system which is preferred and encouraged, even strongly encouraged, but still not absolutely required, in contrast to a mandatory requirement which must be met.
676. oracle. TBD.
677. oracle function. TBD.
678. oracle qubit. TBD.
679. orbital-angular-momentum states. TBD. Shortened as OAM states. Referenced in the Researchers achieve multifunctional solid-state quantum memory article.
680. order-finding. TBD. See also: ordering problem and phase estimation.
681. ordering problem. TBD.
682. organization. A formalized group of individuals who have a common interest and pursue common goals, such as a business or business unit, a government agency, or a non-profit. They have interests, needs, and goals, a budget to meet those goals, and create projects and engage in ongoing operations in pursuit of those goals. They use their budget to hire staff for teams in both projects and operations and to buy or lease products and services for those projects and operations.
683. orthonormal. Vectors which are all unit vectors and all orthogonal to each other.
684. orthonormal bases. TBD. See also orthonormal basis vectors.
685. orthonormal basis vectors. Basis vectors which are orthonormal — each is a unit vector and they are all orthogonal to each other. See the Wikipedia Orthonormal basis article.
686. outcome. A future value or situation, such as the result of some process which may or may not be under the control of the user or program expecting that outcome. Alternatively, synonym for result or measurement — a particular basis state, |0> or |1>. See also: expected outcome, prediction, and outcome basis states.
687. outcome basis states. The possible outcomes for a measurement, which are the basis states, |0> and |1> for a qubit.
688. outcome probabilities. The probabilities for each possible outcome for a measurement of a qubit, one probability for each basis state, |0> and |1>. The probability for an outcome is the square of the modulus (magnitude or absolute value) of the amplitude (probability amplitude) for that basis state in the wave function for the quantum state for the qubit. The sum of the outcome probabilities for all possible outcomes is 1.0, by definition, due to the principle of unitarity.
689. output. See output value. Alternatively, output data — all output values produced by an entity. See also: input.
690. output data. All output values produced by an entity. Synonym for output. See also: input data.
691. output state tomography. TBD. See also: quantum process tomography and quantum state tomography.
692. output value. A data value or signal to be produced by a system, application, component, device, process, function, mapping, or code. See also: input value.
693. overlapping qubits. TBD.
694. P. Initialism for polynomial time. See also: NP.
695. packaging aspects of a quantum computer. Issues related to the physical construction of a quantum computer. How all of the hardware components are physically assembled and connected, including the materials used and their thermal characteristics, especially when ultra-cold superconductors are being used.
696. pair. See pair of qubits. Alternatively, two of anything which are closely associated, possibly even entangled, such as a Bell pair, Cooper pair, or EPR pair.
697. pair of qubits. Two qubits, which may or may not be connected (entangled.) Generally, indicates that they are in fact connected (entangled.)
698. pairs. See pairs of qubits.
699. pairs of qubits. Any number of pairs of connected qubits (entangled qubits.)
700. parallel processor. In addition to a main processor, a multiprocessor computer system may have any number of parallel processors, each of which is capable of the executing the same types of programs as the main processor of a computer system without parallel processors. See also: secondary processors, which can execute only specialized software rather than arbitrary programs as can be done by a main processor.
701. parameter. See function parameter. Alternatively, a configuration parameter.
702. parameterized ansatz circuit. TBD.
703. parametric gates. TBD. See the Analytical modeling of parametrically-modulated transmon qubits paper by Didier, Sete, da Silva, Rigetti. See also: parametrically-activated entangling gates.
704. parametrically-activated entangling gates. TBD. See the Analytical modeling of parametrically-modulated transmon qubits paper by Didier, Sete, da Silva, Rigetti. See also: parametrically-modulated transmon qubits.
705. parametrically-modulated transmon qubits. TBD. See the Analytical modeling of parametrically-modulated transmon qubits paper by Didier, Sete, da Silva, Rigetti. See also: parametrically-activated entangling gates.
706. parametrized ansatz state. TBD.
707. parent class. The OOP class from which a subclass was derived. Also its superclass.
708. partial output state tomography. TBD.
709. partial trace. TBD.
710. partially connected. See partially entangled.
711. partially entangled. Some but not all possible pairs of qubits of a quantum computer may be entangled simultaneously, in contrast with fully entangled, where all possible pairs of qubits may be entangled. Technically, minimally entangled is also partially entangled, but the latter indicates more extensive entanglement, and the former indicates how limited the entanglement is. Partially entangled will also be highly entangled if most pairs of qubits are indeed entangled.
712. particle. An extremely small, localized object. Can range in size from a subatomic particle (elementary particle), photon, free electron, atom or ion, or molecule, to fine powders. Generally, in the context of quantum computing and quantum mechanics, particle will refer to an electron, photon, ion, or an atom or molecule in some cases.
713. particle swarm optimization. TBD. Abbreviated as PSO.
714. passive error suppression. TBD.
715. password. A secret character sequence used as a security measure to provide security for data and systems. See also: cryptographic key.
716. pattern recognition. TBD.
717. pattern recognition tasks in machine learning. TBD.
718. pauli. See Pauli — should be capitalized since it is a person’s proper name.
719. Pauli. Wolfgang Pauli — physicist, pioneer in quantum mechanics, discoverer of the exclusion principle — now known as the Pauli exclusion principle. See the Wikipedia Wolfgang Pauli article.
720. Pauli correction. TBD.
721. Pauli error. TBD.
722. Pauli error rate. TBD.
723. Pauli exclusion principle. Loosely, and somewhat inaccurately, two particles with mass (excludes photons) can not be in the same place at the same time. It’s a little more complicated than that, but it differentiates a lot of the behavior of electrons, protons, neutrons, atoms, and molecules from photons — again, loosely and a bit inaccurately. Synonym for exclusion principle. See the Wikipedia Pauli exclusion principle article for a more accurate but difficult description.
724. Pauli frame. TBD.
725. Pauli gate. TBD.
726. Pauli gate error. TBD.
727. Pauli generator. TBD. See Pauli generators of the Clifford group.
728. Pauli generators of the Clifford group. TBD. Referenced in the Demonstration of Universal Parametric Entangling Gates on a Multi-Qubit Lattice paper by Reagor, et al.
729. Pauli group. TBD. See the Representations of the multi-qubit Clifford group paper by Helsen, Wallman, Wehner.
730. Pauli measurement. TBD. See the Pauli measurements web page from Microsoft.
731. Pauli operator. TBD.
732. Pauli principle. See Pauli exclusion principle.
733. Pauli resetting. TBD.
734. Pauli sequence. TBD.
735. Pauli twirling. See Pauli twirling approximation.
736. Pauli twirling approximation. TBD. Abbreviated as PTA. See the Efficient error models for fault-tolerant architectures and the Pauli twirling approximation paper by Geller and Zhou.
737. Pauli-X gate. Quantum logic gate (operation) which reverses the states of |0> and |1> for a single qubit. This is accomplished by a rotation of the Bloch sphere about the X-axis by pi radians. This is comparable, to the Boolean NOT operation. Abbreviated as X or X gate. See the Wikipedia Quantum logic gate article.
738. Pauli-Y gate. Quantum logic gate (operation) which rotates a single qubit by pi radians about the Y-axis. This is accomplished by a rotation of the Bloch sphere about the Y-axis by pi radians. Abbreviated as Y or Y gate. See the Wikipedia Quantum logic gate article.
739. Pauli-Z gate. Quantum logic gate (operation) which rotates a single qubit by pi radians about the Z-axis. This is accomplished by a rotation of the Bloch sphere about the Z-axis by pi radians. Abbreviated as Z, Z gate, or R-pi. See the Wikipedia Quantum logic gate article.
740. PCB. Initialism for printed circuit board.
741. PEA. Initialism for phase estimation algorithm. See also QPE.
742. performance. How much work a computer can accomplish in a given unit of time. See also: high performance and capacity.
743. period finding. TBD. See also: order-finding and phase estimation.
744. period of time. See interval of time.
745. peripheral device. A device which is attached to a computer and performs some secondary function other than actual computation, including storage, display, output, input, or communication.
746. PFCQC. Initialism for Practical Fully-Connected Quantum Computer Challenge.
747. phase. Generally, stages of a sequence of activities or processing steps. Also, in the physics of waves, refers to both the frequency of a wave and the timing of the zero-crossing of the wave, which can be expressed either as time or the angle in radians which the wave would transit in that time. Also referred to as sign. See the Wikipedia Phase (waves) article. See also phase difference and phase shift. Alternatively, a fraction of a full circle — an angle in radians divided by two pi, so that a phase of 1.0 would correspond to an angle of two pi radians or 360 degrees and a 90-degree angle would be a phase of 0.25. Alternatively, particularly if written in all caps as PHASE, see PHASE gate.
748. PHASE. See PHASE gate.
749. phase coherence time. TBD.
750. phase damping. TBD.
751. phase difference. The difference between the phases of two waves. Can be expressed either as the time distance between their zero crossings, or as the angle in radians that the wave would transit during that time to account for the difference in the zero crossings of the two waves.
752. phase estimation. TBD. See also: period finding and order-finding.
753. phase estimation algorithm. See quantum phase estimation algorithm. Abbreviated as PEA.
754. phase flip error. A quantum error where the phase or sign of a qubit is flipped. [TBD: vague, technical, more detail] See the Wikipedia Quantum error correction article.
755. PHASE gate. Synonym for the RZ gate. A quantum logic gate which rotates a qubit about the Z-axis by a specified angle, in radians. Abbreviated as PHASE.
756. phase kickback. TBD. See the What is phase kickback and how does it occur? Web page from Quora.
757. phase shift. A change in the zero crossing of a wave. Generally a shift in time to move the zero crossing, which can also be expressed as the angle in radians that the wave would transit during that time to shift the wave. Alternatively, a change in the angle of rotation about the vertical, Z axis of the Bloch sphere, commonly known as phi, measured in radians or degrees.
758. phase shift gate. A quantum logic gate which shifts the phase of a qubit — the angle of rotation about the vertical, Z axis of the Bloch sphere, commonly known as phi, measured in radians or degrees, commonly known as phi. See phase shift (R-phi) gates.
759. phase shift (R-phi) gates. A family of quantum logic gate (operation) which modify the phase of a single qubit. [TBD: vague, technical more detail] See the Wikipedia Quantum logic gate article.
760. phase of a qubit. The angle of rotation of the state of a qubit about the vertical, Z axis of the Bloch sphere, commonly known as phi, measured in radians or degrees, commonly known as phi.
761. phase qubit. A qubit based on the phase difference between two superconductors. [TBD: vague, technical, more detail] See the Wikipedia Phase qubit article. See the Quantum behavior of the dc SQUID phase qubit paper. Other types of qubit include charge qubit, flux qubit, and spin qubit.
762. phase term. TBD. Commonly written as (-1)^x.
763. phenomena. More than one instance of a phenomenon or more than one type of phenomenon.
764. phenomenon. An event or activity of a system that is interesting in some way.
765. phi. Refers to the phase of a qubit, the angle of rotation of the quantum state of a qubit about the vertical, Z axis of the Bloch sphere, measured in radians or degrees. See also theta.
766. photon. The smallest unit of visible light and electromagnetic radiation in general.The elementary particle which is the fundamental unit for transfer of energy via electromagnetic radiation. A photon is a boson. A photon is massless. A photon behaves more like a wave than a particle, but it is both. The energy of a photon is proportional to its frequency. See the Wikipedia Photon article.
767. photographic image. An image which was captured using a camera, either a digital camera of a scan of a hard-copy photograph. See also: graphical image.
768. photonic. Relating in some way to light and photons.
769. photonic quantum computation. TBD.
770. photonic quantum computer. TBD.
771. photonic quantum computing. TBD. Synonym for quantum photonic computing. See also: quantum photonic processor.
772. photonic quantum computing chip. TBD.
773. photonic quantum processor. TBD.
774. phrase. A pattern which is a sequence of words, keywords, numbers, or other semantically significant entities, usually within a textual value. Usually excludes punctuation.
775. physical. Relating to entities and conditions in the real world, in contrast to entities and conditions in a computational environment. See also: physical environment.
776. physical body. A localized object, having some distinction from surrounding matter.
777. physical classical computer. The hardware for a classical computer, in contrast to a simulated classical computer or a virtual machine. See also physical classical system.
778. physical classical system. Generally, a reference to a physical classical computer. See also: real classical system.
779. physical computer. The hardware for a computer. See physical system. An actual computer, in contrast to a simulated computer.
780. physical computer system. Either a synonym for physical computer or a physical computer combined with any additional devices or equipment needed to support the operation of the computer. May or may not include the computer software which may be needed to use the computer in order to solve problems.
781. physical connection. A connection between two or more devices using some solid medium, such as wiring, cabling, fiber optic cable, or a waveguide, in contrast with wireless connection (or no connection.)
782. physical entity. Any object, structure, or phenomenon in the physical world, in contrast to a computational entity.
783. physical environment. The physical conditions immediately surrounding and near a physical entity, including location, altitude, orientation, temperature, air pressure, humidity, wind, weather, electromagnetic radiation, solar radiation, cosmic radiation, background radioactive decay, vibration, and movement of other physical entities, any of which may have a physical impact or influence.
784. physical error rate. The percentage of the time that a given quantum logic gate will be compromised by a quantum error, such as noise from the environment or decoherence in general. 1% is common today. See also: quantum error correction (QEC) and quantum error mitigation.
785. physical gate. See physical logic gate.
786. physical logic gate. See quantum physical logic gate, for the purpose of quantum error correction. Otherwise, the reference is simply to the physical hardware, such as the silicon semiconductor which performs a logic operation, either classical or quantum — a classical logic operation or a quantum logic operation. Alternatively, a classical logic gate on an integrated circuit or printed circuit board.
787. physical object. An object which exists in the real world, in contrast to a computational environment.
788. physical operation. An operation which can be performed on a physical qubit, including preparation, logic gate execution, and measurement.
789. physical quantum bit. The hardware which implements a qubit. Alternatively, a qubit on an actual quantum computer, in contrast to a quantum computer simulator. See also: logical qubit. Alternatively, one of a collection of qubits which collectively represent a single quantum logical qubit for the purpose of quantum error correction (QEC).
790. physical quantum machine. See physical quantum computer, physical quantum system, or physical quantum computer system.
791. physical quantum computer. The hardware for a quantum computer. Alternatively, an actual quantum computer, both hardware and software, in contrast to a simulated quantum computer.
792. physical quantum computer system. Either a synonym for physical quantum computer or a physical quantum computer combined with any additional devices or equipment needed to support the operation of the quantum computer. May or may not include the computer software which may be needed to use the quantum computer in order to solve problems.
793. physical qubit. A qubit on a physical quantum computer, in contrast to a simulated quantum computer. Alternatively, one of a collection of qubits which collectively represent a single logical qubit for the purpose of quantum error correction (QEC).
794. physical qubit calibration. Testing and tuning of the hardware parameters for hardware control of a physical qubit. This needs to be done on a fairly frequent and fairly regular basis. See the Physical qubit calibration on a directed acyclic graph paper by Kelly, O’Malley, Neeley, Neven, Martinis of Google. IBM says they calibrate their Q Experience quantum computer twice a day. See also: recalibration.
795. physical machine. See physical computer or physical system.
796. physical medium. The material (medium) in which matter, energy, or information is transmitted or stored.
797. physical quantity. Quantity or quality of a physical system.
798. physical quantum system. Generally, a reference to a physical quantum computer or physical quantum computer system. Alternatively, a reference to a collection of physical bodies, particles, waves, gases, and liquids which are to be analyzed or modeled according to the principles and methods of physics, either classical mechanics for bodies, quantum mechanics for particles and waves, or statistical mechanics for gases and liquids. See also: real physical system and real quantum system.
799. physical system. Generally, a reference to a physical computer, such as a classical computer or a quantum computer. Alternatively, especially in the context of a programmable quantum simulator, a reference to a collection of physical bodies, particles, waves, gases, and liquids which are to be analyzed or modeled according to the principles and methods of physics, either classical mechanics for bodies, quantum mechanics for particles and waves, or statistical mechanics for gases and liquids. See also: real physical system, real classical system, real quantum system.
800. physical world. Anywhere in the universe, in contrast to a computational environment. Synonym for real world.
801. physically-motivated ansatze. TBD. Abbreviated as PMA. In contrast to hardware heuristic ansatze (HHA).
802. pi. Value of pi. Or at least an approximation. The mathematical constant which is the ratio of the circumference of an ideal circle to its diameter.
803. pi Josephson junction. A Josephson junction in which the phase is pi.
804. planar. On the same flat, two-dimensional plane, in contrast to three-dimensions or multiple planes.
805. planar lattice design. An arrangement of hardware components, such as devices on an integrated circuit, in the same flat, two-dimensional plane, in an approximately grid-like configuration. A style of chip layout.
806. Planck constant. The smallest increment of energy in a photon. [TBD: verify] Or, the energy of a photon divided by its frequency. The energy of a photon being its frequency, in hertz or cycles per second, times the Planck constant. See Wikipedia Planck constant article. Denoted by h. See also: reduced Planck constant.
807. Planck’s constant. See Planck constant.
808. plasma. Hot, ionized gaseous matter. See also: solid, liquid, and gas.
809. plasma matter. Matter in the form of plasma. See also: solid matter, liquid matter, and gaseous matter.
810. plasma medium. A medium comprised of plasma, in contrast with solid medium, liquid medium, or gaseous medium. See also: plasma matter.
811. PMA. Initialism for physically-motivated ansatze. See also: HHA.
812. polarised microwave. TBD. Referenced in the Universal holonomic quantum gates over geometric spin qubits with polarised microwaves paper by Nagata, Kuramitani, Sekiguchi, and Kosaka. See also: circularly polarised microwave.
813. polycephalic quantum computer. A particular characterization of quantum computers by physicist Stephen Blaha. See the A Quantum Computer Foundation for the Standard Model and SuperString Theories paper. Polycephaly simply mean having more than one head, suggestive of a multi-tape, multi-head Turing machine.
814. polynomial. See polynomial time and polynomially.
815. polynomial rate. See polynomial time.
816. polynomial time. An algorithm whose cost or complexity grows polynomially as its input grows, in contrast to exponential time. A key goal and benefit of quantum computers is that algorithms take only polynomial time for problems which the best algorithms on a classical computer take exponential time. Class of problems which can be solved by algorithms having a number of steps polynomial in the input size. Abbreviated as P. See also: nondeterministic polynomial time. See the Wikipedia Time complexity article.
817. polynomially. A number raised to a relatively small power, in contrast to exponentially — a relatively small number raised to the nth power. It grows much slower, which is much better, and the hallmark of the quantum advantage. In contrast to superpolynomially.
818. position. Location of an object or other entity in space. See also: direction, distance, and velocity.
819. positive operator-valued measure. TBD. Abbreviated as POVM.
820. post-classical computing. Any form of computing which is more advanced than classical computing. Such as quantum computing.
821. post-Moore’s Law era. The period following the breakdown or deceleration of Moore’s Law, when the density of transistors on an integrated circuit is no longer doubling every couple of years. That’s a negative for classical computing, but an opportunity for quantum computing. We may be in a transition period where doubling of transistor density has slowed from every two years to between two and a half years to three years. What the future holds out three to five to ten years is quite murky at this stage.
822. post-processing. See post-processing of final results.
823. post-processing of final results. Processing of measurement results on a classical computer after execution of a quantum circuit which occurred on a quantum computer, either a physical quantum computer or a simulated quantum computer.
824. post-processing phase. See post-processing of final results.
825. post-quantum cryptography. In the post-quantum cryptography era, new methods are needed which cannot be cracked with a quantum computer. Although, such methods do not exist, yet. See also: quantum-proof cryptography, quantum-resistant cryptography, quantum-safe cryptography, quantum-proof, quantum-safe, and quantum-resistant. See the Wikipedia Post-quantum cryptography article. See the NIST Post-Quantum Cryptography web page. Abbreviated as PQC.
826. post-quantum cryptography era. The era when traditional modern cryptographic methods can be readily cracked using a quantum computer, so new methods are needed which cannot be cracked with a quantum computer. See also: quantum-proof, quantum-safe, and quantum-resistant. See the Wikipedia Post-quantum cryptography article. See the NIST Post-Quantum Cryptography web page.
827. post-quantum cryptography standardization. TBD. See post-quantum cryptography and the NIST Post-Quantum Cryptography web page. Abbreviated as PQC standardization.
828. post-quantum cybersecurity. Cybersecurity in the era of post-quantum cryptography, when traditional modern cryptographic methods can be cracked by quantum computers and newer methods of cryptography are needed, which are quantum-proof, quantum-resistant, and quantum-safe.
829. post-selected ancilla. TBD.
830. post-selection. TBD.
831. post-selection (ancilla verification). TBD.
832. post-selection and purification. TBD.
833. PostBQP. Short for postselected bounded-error quantum polynomial time.
834. postselected bounded-error quantum polynomial time. Bounded-error quantum polynomial time (BQP) with postselection. Any problem which can be solved on a quantum computer in polynomial time correctly at least two-thirds of the time — errors are bounded to no more than one-third of the time — and which has an additional output qubit which can be selected (measured) for the |1> basis state. Abbreviated as PostBQP. See the Wikipedia PostBQP article and the Quantum Computing, Postselection, and Probabilistic Polynomial-Time paper by Aaronson. See also: postselected bounded-error quantum polynomial time or PostBQP.
835. postselection. See postselection qubit and PostBQP.
836. postselection qubit. An additional output qubit of a quantum circuit which can be measured for the |1> basis state. See also: postselected bounded-error quantum polynomial time.
837. POVM. Initialism for positive operator-valued measure.
838. power. See electrical power. Alternatively, synonym for high performance.
839. power grid. See electrical power grid.
840. power plant. See electrical power plant.
841. power source. See electrical power source.
842. power supply. See electrical power supply.
843. powerful. See high performance.
844. PQC. Initialism for post-quantum cryptography.
845. PQC standardization. Short for post-quantum cryptography standardization.
846. practical. Relates to real-world problems. Alternatively, relates to a level of effort and resources which is considered reasonable and not excessive. See also: practical problem, practical solution, practical needs, practical cost, and practical project.
847. practical application. An application which addresses a practical problem at a practical cost.
848. practical cost. The financial and lost-opportunity cost of a project is considered acceptable and not excessive. It won’t break the budget or put other projects at risk.
849. practical fully-connected quantum computer. A fully-connected quantum computer which is not only theoretically possible, but can be practically constructed today, emphasizing that any qubit can be entangled with any other qubit, rather than being limited to to only certain pairs of qubits.
850. Practical Fully-Connected Quantum Computer Challenge. An NSF project for a practical fully-connected quantum computer. Abbreviated as PFCQC.
851. practical problem. A problem which is of practical interest to an organization or individual, in contrast to a theoretical problem, a research problem, or an experimental problem. Its solution meets needs of users and the organization. See also: real-world problem and practical, real-world problem.
852. practical interest. Relating to the reasonable and pressing needs and interests of a user or organization, and for which a solution is considered practical.
853. practical need. See practical problem and practical interest.
854. practical project. A project which is technically feasible, has a reasonable cost, and addresses a significant real-world problem of practical interest to the organization. See also: practical problem and practical cost.
855. practical quantum computer. See viable quantum computer, with emphasis on the extent to which real, practical problems can be solved using the quantum computer. Alternatively, a theoretical quantum computer which would be a viable quantum computer if it were to be built, eventually. Alternatively, a quantum computer which is both a viable quantum computer and a current quantum computer.
856. practical quantum computing. Computing with a practical quantum computer. Active use of a practical quantum computer. Using a quantum computer to produce practical solutions to practical problems.
857. practical quantum supremacy test. There is no universally agreed upon benchmark test for what exactly constitutes quantum supremacy. This paper, Characterizing Quantum Supremacy in Near-Term Devices, is one proposal for a quantum supremacy test.
858. practical, real-world problem. Redundant, but emphasizes the need to focus on practical problems and real-world problems, coupled with practical, real-world solutions.
859. practical, real-world solution. Redundant, but emphasizes the need to focus on practical solutions and real-world solutions — for practical, real-world problems.
860. practical-scale quantum computer. See practical quantum computer, emphasizing sufficient capacity (qubit count) for real-world problems.
861. practical solution. Solution which satisfies practical needs and requires only a practical level of effort, resources, and cost even if not an optimal solution. It’s good enough. See also: approximate solution, exact solution, practical cost, real-world solution, and practical, real-world solution.
862. precise solution. See exact solution.
863. prediction. Either speculation or the use of a theory to deduce an expected outcome.
864. preparation. See quantum logic circuit preparation.
865. preparation logic. See quantum logic circuit preparation.
866. preparation phase. See quantum preparation phase. See also execution phase and measurement phase.
867. preparation steps. See quantum logic circuit preparation.
868. present-day quantum hardware. See current quantum computer or current general purpose quantum computer.
869. primary control logic. See control logic and host program.
870. prime. See prime number.
871. prime number. An integer for which there is no collection of integers other than 1 and itself which can be multiplied together to produce the original integer. See also: encryption key and prime factorization.
872. prime factorization. See prime factorization problem. See the Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer paper by Shor. See also: factoring integers.
873. prime factorization problem. The subset of the integer factorization problem where the collection of of integers whose product is the original integer has exactly two integers, both of which are prime. This is the essence of cracking an encryption key, which is a very large integer which is the product of two reasonably large prime numbers. See the Wikipedia Integer factorization article. See also: crack a cryptographic key.
874. primitives. TBD.
875. principle of unitarity. See unitarity. The sum of the probabilities for all possible outcomes for a quantum system is 1.0, by definition.
876. principles of operation. A general and detailed specification and description of everything that a software developer needs to know to work with a system directly, without any intervening layers of software, not even an operating system. This does not detail the internal implementation of the system, only the details that the software developer can observe, detect, and control. An architecture specification will typically include more of the internal detail. For a software system, the functional specification and API specification should be sufficient. For a hardware system, such as a computer, the principles of operation would be equivalent to the functional specification and API specification for software. See also: programming model.
877. principles of quantum computing. See quantum computing principles.
878. principles of quantum mechanics. The principles of quantum mechanics, especially superposition, entanglement, and quantum decoherence.
879. printed circuit board. Flat, non-conductive sheet of material upon which the electronic components, including both discrete electronic components and integrated circuits, and their interconnections for an electronic circuit can be etched and fastened, in contrast to an integrated circuit. See the Wikipedia Printed circuit board article. Abbreviated as PCB.
880. probabilistic result. The quality of measurement and results on a quantum computer, which gives them at least somewhat of a nondeterministic quality, due to the underlying nature of quantum mechanics, upon which quantum computers are based. See also: probability amplitude, deterministic result, and nondeterministic result.
881. probability. Chance or likelihood of a given outcome or of a quantum system being in a particular quantum state. A real number which is the square of the modulus of the probability amplitude of a quantum state — the sum of the squares of the real part and imaginary part of the probability amplitude. A number between 0.0 and 1.0. The sum of the probabilities of all possible outcomes or all possible quantum states is, by definition, 1.0. See also: probability amplitude.
882. probability amplitude. A complex number which is the representation in the wave function of a quantum system, such as a single qubit or collection of qubits, of the probability that the quantum system is in a particular quantum state. It is not the actual probability, but the square of the modulus of the probability amplitude is the actual probability — the modulus of the probability amplitude is the square root of the probability. The sum of the probabilities (not amplitudes) for all possible quantum states of the quantum system (a single qubit or collection of qubits) is, by definition 1.0. See the Wikipedia Probability amplitude article. See also: eigenvalues and eigenvectors and quantum amplitude.
883. probability distribution. The probability of each possible outcome or quantum state over some interval of all or a subset of all possible outcomes or quantum states. See the Wikipedia Probability distribution article.
884. problem. A situation which is considered undesirable or otherwise problematic for some reason and in need of a solution, to transform the situation to a more optimal situation. A problem may be a practical problem, a research problem, or a theoretical problem. See also opportunity and solution.
885. process. A computer program which is executing has its own state independent of other processes which are executing on the same computer. The operating system is responsible for scheduling the execution of processes, especially when there are more processes or programs than processors on the computer, and also responsible for saving and restoring or switching state when execution switches between processes. This concept exists only on classical computers at this time — there is no equivalent concept on a quantum computer. Alternatively, some sequence of steps required to accomplish some task or to achieve some goal, with a beginning, middle, and end. Alternatively, a reference to processing.
886. process communication. See interprocess communication.
887. process fidelity. TBD.
888. process synchronization. The ability of two processes to synchronize their execution, either to assure that they execute at the same time, or to assure that they do not.
889. processed measurement results. See post-processing.
890. processing. The act or activity of sequencing through the steps of a process. See also: processing step.
891. processing step. One of the series of steps in a process.
892. processor. The main, central portion of a computer, where the bulk of computation is performed. Alternatively, a secondary processor or parallel processor of a multiprocessor computer system. See also: central processing unit (CPU).
893. processor chip. A processor which is fully implemented using a single integrated circuit chip.
894. product. A physical object which a vendor is offering for customers to purchase or lease, in contrast to a research project or technology which is not yet fully developed and available for purchase. See also service.
895. product development. The process of constructing a product. See also: software development and product development stage.
896. product development process. The process which is to be used to construct a product. See also: product development, software development, and product development stage.
897. product development stage. The stage in the development of product based on a technology where the research stage and the experimental stage have been completed and there is no question about the practicality of products based on the technology. Upon completion of the product development stage, the technology and product will re ready for the commercial availability stage. Alternatively, any of the numerous stages of product development, stages or steps in the product development process.
898. product form. TBD.
899. product formula algorithm. TBD.
900. product state. TBD. See the Wikipedia Separable state article. See also: separable state and entangled state.
901. production. Actual use of a technology, product, service, or system in the real world, serving end-users with real-world applications. See production deployment.
902. production deployment. The stage after development where a technology, product, service, or system is not only production-ready, but is actually put into production, use, serving end-users with real-world applications, in contrast to experimentation and testing.
903. production-ready. A technology, product, service, or system is ready to be put into service (production) serving end-users for real-world applications, in contrast to experimentation and testing. Implies that experimentation and testing have been completed.
904. program execution. Execution of a computer program. See quantum program execution. Alternatively, execution of a classical computer program.
905. programmer. An individual who engages in programming. A computer programmer or a quantum programmer. Also a software developer.
906. programmable quantum simulator. A quantum program which implements programmable quantum simulation to simulate the quantum physics of a physical system.
907. programmable quantum simulation. The use of a quantum computer to simulate the quantum mechanics of a physical system — the actual physics. Technically the quantum computer could be a quantum computer simulator running on a classical computer, but the raw computational power needed to simulate quantum physics would tend to require the raw power of a physical quantum computer. See the Programmable Quantum Simulation by Dynamic Hamiltonian Engineering paper by Hayes, Flammia, and Biercuk, and the Using Quantum Computers for Quantum Simulation paper by Brown, Munro, and Kendon.
908. programming. The development of computer programs, either for a classical computer or a quantum computer. Both design and coding. The process of implementing algorithms. May or may not include design and development of the algorithms themselves. See also: software development. Also computer programming and quantum programming.
909. programming language. The language used to express a computer program. May range from assembly language to high-level languages, even to higher-level languages. See also: specialized programming language.
910. programming language compiler. A software tool which can transform the source code for a computer program into a form more suitable for execution, either the final executable code format or an intermediate representation. May be shortened to compiler.
911. programming model. A detailed specification of the features of a computer or system which the developer may use and the rules which they must follow, as well as guidance for how real-world problems can be mapped into use of the capabilities of the computer and its software. In short, how the programmer can program the computer effectively. Alternatively, a brief summary of the features and rules. See also: quantum abstract machine, instruction set architecture, and principles of operation.
912. programming of quantum computers. Programming with the intent of executing the program on a quantum computer.
913. project. A group of professionals and other individuals who have been brought together for a purpose, to achieve a goal or to pursue an interest, such as to develop a product. See also: team and organization. Alternatively, as a verb, to project — see projecting and projection.
914. projecting. The process of mapping (projecting) the wave function for a quantum state to a particular basis state, such as |0> or |1> for a qubit. See projection. See also: measurement, result, and outcome.
915. projection. The act of projecting the wave function for a quantum state to a particular basis state, such as |0> or |1> for a qubit. Alternatively, the result of projecting the wave function for a quantum state to a particular basis state, such as |0> or |1> for a qubit. Synonym for measurement or result. The probabilities, represented as the amplitudes or probability amplitudes, of the basis vectors which comprise the quantum state will influence the result of the projection, but will not guarantee a particular outcome, unless the quantum state is a pure state — not a superposition of two basis states.
916. projection postulate. See projection postulate of quantum physics.
917. projection postulate of quantum physics. TBD.
918. projective measurement. TBD. See also: general measurement and projection.
919. projector. TBD.
920. promise of quantum computing. Vague notion of a perceived advantage of quantum computing over classical computing for both performance and capacity. Has yet to be quantified. In theory it will be significant, but this has yet to be proven as much more research and development remains needed.
921. proper name. Formal name for an individual, either for a person, place, or a non-person as if they were a person, intending to acknowledge their social significance rather than being a strictly arbitrarily assigned identifier.
922. property. An aspect of an entity which can be observed, measured, detected, or modeled, directly or indirectly. Synonym for characteristic, quality, and attribute.
923. proposal. An effort and document advocating for either a new project or the acquisition of a product or service, seeking management approval after management review.
924. protocol. A collection of data formats, rules, and processes for communicating between two or more devices, such as computers. See also: digital protocol and Internet protocol.
925. prototype. A subset or approximation of a product implemented for the purpose of experimentation and demonstration of a nascent technology or conceptual approach. Feedback from working with a prototype can then be used to firm up plans for the real product. See also: working prototype.
926. prototyping. The process of validating, testing, evaluating, and demonstrating proposals for a product or service by building a prototype which can actually function as desired, or at least approximate the desired function. See also: working prototype.
927. PSO. Initialism for particle swarm optimization.
928. PSWAP. See PSWAP gate.
929. PSWAP gate. A quantum logic gate which swaps the quantum state of two qubits plus a specified (parameterized) phase shift, in radians. The phase shift is applied to the first qubit if it is in the |1> basis state and applied to the second qubit if it is in the |0> basis state. Abbreviated as PSWAP. [TBD: 1) is it a shift of phase or a setting of phase and 2) is the condition before the swap or of the state being swapped in?] Referenced in Source Code Documentation — pyquil.api from Rigetti Computing. See also: SWAP gate, CSWAP gate, and ISWAP gate.
930. PTA. Initialism for Pauli twirling approximation.
931. public-key. See public key.
932. public key. See traditional modern public key.
933. public-key cryptographic algorithm. See traditional modern public-key cryptographic algorithm. See also: quantum cryptographic algorithm.
934. public-key cryptographic method. See traditional modern public-key cryptographic method. See also: quantum cryptography.
935. public-key cryptography. See traditional modern public-key cryptography. See also: quantum cryptography.
936. punctuation. Characters used to separate words, numbers, names, or any other semantically significant entities in text, in an expression in some language, including both natural language and programming languages.
937. pure state. A quantum state which is either a basis state, |0> or |1>, or a rotation of a basis state. Its complex vector will be on the surface of the Bloch sphere. In contrast to a mixed state, whose complex vectors each have an amplitude less than 1.0, so that they are now inside rather than on the surface of the Bloch sphere. [TBD: verify] See the Wikipedia Quantum state article.
938. pure state entanglement distillation and dilution. TBD.
939. pure-state N-representability conditions. TBD.
940. pure-state N-representable manifold. TBD.
941. pure-state projection. TBD.
942. purity. TBD.
943. purity limit. TBD.
944. purity measurement. TBD.

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