# Quantum Computing Glossary — Part 4 — Q

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

- Quantum Computing Glossary — Introduction.
- Quantum Computing Glossary — Part 1 — A-C.
- Quantum Computing Glossary — Part 2 — D-G.
- Quantum Computing Glossary — Part 3 — H-P.
- Quantum Computing Glossary — Part 4 — Q. This part.
- Quantum Computing Glossary — Part 5 — R-S.
- Quantum Computing Glossary — Part 6 — T-Z.

# Q

**QA.**Initialism for*quantum annealer*,*quantum annealing*, and*quantum annealing system*.**QA&A.**Initialism for*quantum algorithms & applications*or*quantum algorithms and applications*.**QAA.**Initialism for*quantum amplitude amplification*.**QAC.**Initialism for*quantum adiabatic computing model*.**QAE.**Initialism for*quantum autoencoder*and*quantum autoencoder algorithm*.**QAHE.**Initialism for*quantum anomalous Hall effect*.**QAM.**Initialism for*quantum abstract machine*.**QAOA.**Initialism for*quantum approximate optimization algorithm*. Alternatively, initialism for*quantum alternating operator ansatz*.**QAOA ansatz.**TBD.**QASM.**Initialism for*quantum assembly language*.**QBC.**Initialism for*quantum bit commitment*.**qbit.**See*qubit*and*quantum bit*. More proper to use*qubit*.**QC.**Initialism for*quantum computing*,*quantum computation*, or*quantum computer*.**QCA.**Initialism for*quantum cellular automaton*.**QCCD.**Initialism for*quantum charge-coupled device*.**QD.**Initialism for*quantum dot*.**QD quantum computing.**See*quantum dot quantum computer*.**QDQC.**Initialism for*quantum dot quantum computer*.**QEC.**Initialism for*quantum error correction*.**QECC.**Initialism for*quantum error-correcting codes*.**QEM.**Initialism for*quantum error mitigation*.**QFA.**Initialism for*quantum finite-state automaton*.**QFT.**Initialism for*quantum Fourier transform*in the context of*quantum computing*or*quantum field theory*in the context of*quantum mechanics*.**QKD.**Initialism for*quantum key distribution*.**QLA.**Initialism for*quantum-limited amplifier*.**QMC.**Initialism for*quantum Monte Carlo*.**QMI.**Initialism for*quantum machine instruction*.**QML.**Initialism for*quantum machine learning*.**QND.**Initialism for*quantum non-demolition*or*quantum non-demolition measurement*.**QNN.**Initialism for*quantum neural network*or*quanvolutional neural network*.**QOFA.**Initialism for*quantum-order finding algorithm*.**QPE.**Initialism for*quantum phase estimation*.**QPEA.**Initialism for*quantum phase estimation algorithm*. Alternatively,*QPE*or*PEA*.**QPT.**Initialism for*quantum process tomography*.**QPU.**Initialism for*quantum processing unit*.**QPU element.**Short for*quantum processing unit element*.**QST.**Initialism for*quantum state tomography*.**qRAM.**Initialism for*quantum random access memory*.**QRAM.**See*qRAM*.**QTM.**Initialism for*quantum Turing machine*.**quadratic complexity.**An*algorithm*whose*computational complexity*is approximately the square of its input size —*O(n²)*. Not to be confused with a*quadratic speedup*which is essentially the inverse of*quadratic complexity*—*O(sqrt(n))*.**quadratic speedup.**An*algorithm*which exhibits a*computational complexity*of*O(sqrt(n))*compared to an algorithm of*linear complexity*,*O(n)*. An example is*Grover’s algorithm*. Not to be confused with*quadratic complexity*,*O(n²)*— a*quadratic speedup*is essentially the inverse of*quadratic complexity*. See thepaper.*What Is Quantum Advantage and What Is Quantum Supremacy?***quadratic unconstrained binary optimization problem.**The type of*optimization problem*which is particularly well-suited for a*quantum annealer*, such as the D-Wave*special-purpose quantum computer*. Abbreviated as*QUBO*. See thepaper by Mark Lewis and Fred Glover.*Quadratic Unconstrained Binary Optimization Problem Preprocessing: Theory and Empirical Analysis***quality.**An aspect of an*entity*which can be observed, measured, detected, or modeled, directly or indirectly. See also:*characteristic*,*property*, and*attribute*. Alternatively, the degree to which a*product*or*service*satisfies its*users*. Ranging from low quality to high quality. Largely subjective, but sometimes metrics can be defined and measured or calculated. Metrics could include bugs, performance, and response time. For a*quantum computer*,*coherence*would be a prime metric.**quanta.**Smallest physically possible unit of some*physical quantity*. The smallest amount of a*physical quantity*which can be*measured*. The smallest*measure*of a*physical quantity*. For example, a*photon*of*light*or*electromagnetic radiation*.**quantify.**Count or measure something.**quantity.**Something that can be quantified. Alternatively, the count or measure of something. This term can be used either way, to refer to that which is being counted or measured, or alternatively to refer to the actual count or measurement. In*quantum mechanics*, there is a correspondence between an*operator*, an*observable*, and a*quantity*of the*quantum system*under study. In*quantum computing*,*quantity*can refer to the*quantum state*of a*qubit*, both as it exists as a*superposition*of*quantum states*and also as it would be*measured*as a*real quantity*in the form of a*real number*. See also:*real quantity*.**quantitative and operational connection.**TBD.**quantum.**General reference to*quantum computing*or to the*principles of quantum mechanics*. Alternatively, in context, a general reference to the concept of the smallest, individual, discrete, indivisible*unit*by which two phenomena, observations, or measurements can differ.**quantum abstract machine.**A*programming model*for a*quantum computer*. The*features*which the*developer*may use and the*rules*which they must follow. Abbreviated as*QAM*. See thepaper by Smith, Curtis, and Zeng of Rigetti Computing.*A Practical Quantum Instruction Set Architecture***quantum acyclic circuit.**TBD. Analogous to acyclic circuits in classical computer science.**quantum adiabatic computing model.**TBD. Abbreviated as*QAC*.**quantum adiabatic theorem.**If*environmental conditions*are evolving slowly enough, the*quantum system*can adapt accordingly, but if*environmental conditions*are evolving too rapidly, the system will not evolve significantly. See the Wikipediaarticle.*Adiabatic theorem***quantum advantage.**At least in the context of a particular*application*of interest, a*quantum computer*can perform a*computation*significantly faster than even the best*classical computer*or no*classical computer*may be able to perform the*computation*at all — or at least not in some reasonable amount of time or with a reasonable number of*classical computers*in a*distributed*or*networked*configuration. Note that a*quantum advantage*in one or more*applications*does not necessarily imply an overall*quantum advantage*in any other*application*or across all*applications*. The central essence of*quantum advantage*is*quantum parallelism*which enables*quantum algorithms*to*execute*with a*computational complexity*which is*polynomial*in contrast with*classical algorithms*which tend to have a greater (worse)*computational complexity*which is*superpolynomial*, such as*exponential*. Or in general, the*computational complexity*of an*algorithm*on a*quantum computer*grows significantly more slowly than for the best comparable*algorithm*on the best*classical computer*as the size of the*input*or*complexity*of the*problem*to be solved grows —*Big-O*for a*quantum algorithm*on a*quantum computer*is much smaller than*Big-O*for the best*algorithm*on a*classical computer*. May sometimes be used as a synonym for*quantum supremacy*,*quantum preeminence*, or*quantum ascendency*. May refer to a specific characterization of how much faster or better a*quantum computer*can*execute*a particular*algorithm*compared to a comparable*algorithm*on a*classical computer*— the specific advantage. See also:*quantum speedup*. May also refer to the*eventual*advantage and*promise*of*quantum computers*, as opposed to*capabilities*which are available today or likely will be in the fairly near-term future. [TBD: See more discussion in the (upcoming)paper.]*What Is Quantum Advantage and What Is Quantum Supremacy?***quantum algorithm.**An*algorithm*designed to be*executed*on a*quantum computer*. A*quantum algorithm*would be implemented by a*quantum logic circuit*or a*quantum program*. See also:*famous quantum algorithms*.**quantum algorithm design.**The*process*of*designing*a*quantum algorithm*. Creating a*quantum algorithm*. Construction of a*quantum algorithm*. See also:*quantum programming*.**quantum algorithm designer.**An*individual*, typically a*professional*, who*designs**quantum algorithms*. See also:*quantum programmer*.**quantum algorithms & applications.**See*quantum algorithms and applications*. Abbreviated as*QA&A*.**quantum algorithms and applications.**Both*quantum algorithms*and*quantum applications*—*applications*which use*quantum algorithms*. Abbreviated as*QA&A*. Also written as*quantum algorithms & applications*.**quantum algorithms and software.***Quantum algorithms*,*quantum logic circuits*, and*quantum programs*, collectively. In addition, may include any complementary*classical software*for a*hybrid mode of operation*.**quantum alternating operator ansatz.**A*quantum algorithm*for combinatorial optimization problems which extends the concept of a*quantum approximate optimization algorithm*by allowing alternation between more general families of operators with general parameterized families of unitaries rather than only those corresponding to the time evolution under a fixed local Hamiltonian for a time specified by the parameter. Abbreviated as QAOA, but may be confused with*quantum approximate optimization algorithm*, which has the same abbreviation. See thepaper by Hadfield, Wang, O’Gorman, Rieffel, Venturelli, and Biswas.*From the Quantum Approximate Optimization Algorithm to a Quantum Alternating Operator Ansatz***quantum amplifier.**TBD.**quantum amplitude.**See*probability amplitude*. The*probability amplitude*for a*qubit*being in a particular*quantum basis state*, |0> or |1>, a*complex number*, the square of whose*modulus*(*absolute value*) is the*probability*that the*qubit*is in that particular*quantum basis state*. Each*quantum basis state*has its own*amplitude*(*probability amplitude*.) When a*qubit*is in a*quantum state*which is a*superposition*of two*quantum basis states*, each has its own*quantum amplitude*and hence*probability*. The sum of those*probabilities*is, by definition, 1.0. For example, after*execution*of the*Hadamard (H) gate*, the*probability*of being in the |0>*state*is 0.5 and 0.5 for the |1>*state*as well, also meaning that the*probability*that*measurement*of the*qubit*would return 0 is 0.5 and 0.5 for 1 as well. The actual*probability amplitude*would be a*complex number*, the square of whose*modulus*would be 0.5. By definition,*quantum amplitude*itself is neither visible, observable, detectable, or measurable for a*quantum system*or a*quantum computer*— once a*qubit*is*measured*, the*quantum amplitudes*are lost as the*quantum state*(*wave function*)*collapses*to the particular*value*returned by the*measurement*.**quantum amplitude amplification.**TBD. See the Wikipediaarticle. See the*Amplitude amplification*paper by Brassard, Hoyer, Mosca, and Tapp. See*Quantum Amplitude Amplification and Estimation*web page in IBM Q Experience documentation. See also:*Grover’s Algorithm**Grover’s algorithm*,*amplitude estimation*, and*oblivious amplitude amplification*. Abbreviated as*QAA*. Commonly shortened as*amplitude amplification*.**quantum analog computer.**Vague term, but sometimes applied to a*quantum annealing processor*or*adiabatic quantum computing*. Synonym for*analog quantum computer*.**quantum annealer.**See*quantum annealing computer*.**quantum annealing.**An*algorithm*for finding the global minimum for a*function*(an*objective function*.) [TBD: summarize utility]. See the Wikipediaarticle. See also*Quantum annealing**quantum annealing computer*,*simulated annealing*, and*reverse quantum annealing*. Abbreviated as*QA*.**quantum annealing computer.**A*quantum computer*which is*programmed*for*quantum annealing (QA)*.**quantum annealing processor.**See*quantum annealing computer*.**quantum annealing system.**See*quantum annealing computer*.**quantum anomalous Hall effect.**TBD. Potential for construction of*qubits*for a*topological quantum computer*. Shortened as*QAHE*. See the Wikipediaarticle. See the*Quantum anomalous Hall effect*paper. See the*The quantum anomalous Hall effect*paper.*Prospect of quantum anomalous Hall and quantum spin Hall effect in doped kagome lattice Mott insulators***quantum application.**See*quantum computer application*.**quantum approximate optimization algorithm.**A*quantum algorithm*which computes approximate solutions for combinatorial optimization problems. Abbreviated as QAOA. See thepaper by Farhi, Goldstone, and Gutmann. See also:*A Quantum Approximate Optimization Algorithm**quantum alternating operator ansatz*.**quantum ascendancy.**Synonym for*quantum supremacy*,*quantum preeminence*, and*quantum advantage*. Alternatively, recognizing that*quantum computing*is rising steadily and rapidly, and at a rate faster than the capacity and performance of*classical computers*. Although, it’s not abundantly clear that that is the case at this time, yet.**quantum assembly language.**A*programming language*(*assembly language*) used to express a*quantum program*or*quantum logic circuit*in terms of individual*quantum logic gates*, roughly comparable to a*classical assembly language*but for a*quantum computer*. Shortened as*QASM*. See also:*OpenQASM*and*QUIL*. Synonym for*assembly language for quantum computers*.**quantum assembly language code.***Source code*written in a*quantum assembly language*.**quantum-assisted learning.**TBD.**quantum-assisted machine learning.**TBD.**quantum associative memory.**The ability to store*patterns*and then look up a*pattern*given only a portion of the*pattern*, using a*neural network*to store the patterns based on*qubits*. See thepaper.*Quantum Associative Memory***quantum associative memory algorithm.**An*algorithm*for the design of a*quantum associative memory*.**quantum autoencoder.**See*quantum autoencoder algorithm*. Abbreviated as*QAE*.**quantum autoencoder algorithm.**TBD. Abbreviated as*QAE*.**quantum automata.**The adaptation of the concept of*automata*to*quantum computing*. [TBD: more detail] See thepaper. See also*Quantum Automata and Quantum Grammars**quantum language*and*quantum grammar*.**quantum-based technologies.***Quantum computing*,*quantum communication*, or any other*technology*whose primary function is based on*quantum mechanics*, especially*qubits*. Referenced inbill.*National Quantum Initiative Act***quantum basis.**See*basis*. The set of*quantum basis states*from which all*quantum states*are*composed*, as*linear combinations*.**quantum basis state.**See*basis state*. One of the*quantum states*forming a set from which all*quantum states*are*composed*as*linear combinations*.**quantum bath.**TBD. See also:*bath*and*open quantum system*.**quantum biology.**TBD.**quantum bit.**The fundamental*unit*of*value*on a*quantum computer*, which may be a*superposition*of a 0 and a 1, using the*quantum states*of |0> and |1>, in contrast to the*classical bit*of a*classical computer*which can only represent a single*value*, either a 0 or a 1. Where*quantum information*is stored. Commonly referred to as a*qubit*. A single*qubit*can represent two*values*simultaneously while a*classical bit*can only represent a single value at any moment. Two*qubits*can represent four*values*simultaneously, a*classical bit*only two.*n**qubits*can represent 2 to the*n**values*or*quantum states*simultaneously, while*n**classical bits*can only represent*n**values*(each a single*classical bit*) at only moment.*Qubits*can also be*entangled*. The primary downside to a*qubit*is that its value cannot be*read*(*measured*) without causing its*superimposed quantum state*to*collapse*to a single*value*. Another significant downside is that current*quantum technology*requires that*qubits*be chilled to near*absolute zero*in order to support*superposition*and*entanglement*. Alternatively, in the context of*quantum communication*and*quantum teleportation*, the*quantum state*to be*teleported*. See the Wikipediaarticle. See also:*Qubit**qutrit*,*qudit*,*stationary qubit*,*flying qubit*.**quantum bit commitment.**A protocol for*quantum cryptography*and*quantum communication*. [TBD: more detail]. See the Wikipediaarticle. See the*Commitment scheme*paper. Abbreviated as*Quantum bit commitment and the reality of the quantum state**QBC*.**quantum braid.**A stable configuration of*anyon quasiparticles*which can be used to construct a*qubit*for a*topological quantum computer*. See the Wikipediaarticle.*Topological quantum computer***quantum bus.**The equivalent of a*classical bus*, but for a*quantum computer*.*Interconnections*for controlling and interconnecting*qubits*, including*entanglement*, such as using*microwaves*in*waveguides*. See the Wikipediaarticle.*Quantum bus***quantum C language.**A hypothetical variant of the C*classical programming language*adapted to*quantum computing*. Proposed by Stephen Blaha in his paper,. As of June 2018, there is no*Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C Language**implementation*of this conception.**quantum calibration.**See*physical qubit calibration*.**quantum calculation.**See*quantum computation*, possibly with more of an emphasis on*numerical calculation*.**quantum cellular automaton.**The concept of a*cellular automaton*adapted to a*quantum computer*. See the Wikipediaarticle. Abbreviated as*Quantum cellular automaton**QCA*.**quantum channel.**See*quantum communication channel*.**quantum chaos.**See*quantum chaos theory.***quantum chaos theory.***Classical chaos theory*for*dynamical systems*adapted to*quantum mechanics*and*quantum computing*. See the Wikipedia**Chaos theory**article. See the Wikipediaarticle.*Quantum chaos***quantum charge-coupled device.**TBD. Abbreviated as*QCCD*.**quantum chemist.**TBD.**quantum chemistry.**TBD.**quantum chemistry simulation algorithm.**TBD.**quantum chemistry study.**TBD.**quantum chip.**An*integrated circuit*containing one of more*qubits*and associated*circuitry*needed to directly control that*qubit*.**quantum chip interconnect.**The physical, mechanical and electrical connection*technology*used to interface a*qubit*to the rest of a*quantum computer*.**quantum circuit.**See*quantum logic circuit*.**quantum circuit abstraction.**See*quantum logic circuit abstraction*.**quantum circuit designer.**Someone who conceptualizes and defines*quantum circuits*— sequences of*quantum logic gates*. Synonymous with*quantum programmer*and*quantum developer*. May also include design of*classical computer programs*which in turn embody or generate*quantum circuits*or portions of*quantum circuits*which may be combined or*executed*separately to form a complete*quantum application*.**quantum circuit execution.**See*quantum logic circuit execution*.**quantum circuit generation.**See*quantum logic circuit generation.***quantum circuit intermediate representation.**See*quantum logic circuit intermediate representation.***quantum circuit IR.**See*quantum circuit intermediate representation*.**quantum circuit model.**See*quantum circuit model of computation*.**quantum circuit model of computation.**The model for performing*computation*on a*quantum computer*as a*quantum logic circuit*which consists of a*sequence*of*quantum logic gates*or*operations*. For a discussion of this model as well as alternatives, see theMIT PhD thesis by Stephen Paul Jordan.*Quantum Computation Beyond the Circuit Model***quantum circuit processing.**The portion of the*logic*of a larger*algorithm*, typically a*quantum/classical hybrid algorithm*, which is implemented using a*quantum circuit*. Alternatively, the logic which is implemented by a*quantum circuit*.**quantum circuit validation.**Review and checking of a*quantum circuit*for logic and consistency issues before it is to be*executed*.**quantum circulator.**A*device*for controlling the flow of a*microwave*signal in a*quantum computer*. This is a*microwave circulator*, but simply specialized for the needs of a*quantum computer*.*Microwaves*are used to control*qubits*, so careful control of the flow of*microwaves*is needed to minimize*quantum decoherence*. See the Physicsarticle (synopsys.)*Synopsis: Quantum Circulators Simplified***quantum and classical future.**The era when both*quantum computing*and*classical computing*are both very relevant, each having its own strengths and own weaknesses. Synonym for*classical and quantum future*.**quantum/classical hybrid algorithm.**See*quantum hybrid algorithm*. Also written as*hybrid quantum/classical computing*.**quantum-classical boundary.**TBD.**quantum-classical interface.**The*software*and*hardware*needed for a*classical computer*to communicate with and control a*quantum computer*. Alternatively, the*electronic circuitry*needed to connect classical, binary*digital circuitry*to a*qubit*.**quantum cloud service.**One or more*quantum computers*available as a*cloud-based service*on the*Internet*. The user connects remotely and queues up a*quantum program*to be*executed*remotely when a*quantum computer*of the given type is available. The user will be notified when*quantum program execution*has been completed and*final results*of the*quantum computation*are available.**quantum co-design.**See*quantum codesign*.**quantum code.**A*quantum program*or*quantum circuit*as*implementation*of a*quantum algorithm*designed to run on a*quantum computer*, in contrast to*classical code**designed*to*execute*on a*classical computer*.**quantum codesign.***Codesign*for*quantum algorithms*and*quantum computers*— collaborative*design*with the intention of achieving a much more optimal design for both.*Quantum algorithms*and the*quantum computer*on which those*algorithms*will run are*designed*at the same time, feeding knowledge about the*algorithms*into*design*of the*quantum computer*and knowledge about the*quantum computer*into*design*of the*quantum algorithms*, as well as feedback loops between both*design*processes. May be referred to simply as*codesign*or*co-design*. Also written as*quantum co-design*.**quantum cognition.**An attempt to model the human mind in a*quantum-like*manner, but not necessarily implying that*quantum mechanics*is needed to explain the operation of the brain and neurons, although there is that possibility — see*quantum mind*. See the Wikipediaarticle. See the*Quantum cognition*paper. See the*Quantum cognition: a new theoretical approach to psychology*article from*How ‘Quantum Cognition’ Can Explain Humans’ Irrational Behaviors**The Atlantic*. See the Wikipediaarticle.*Quantum mind***quantum coherence.**The ability of a*quantum computer*to maintain its*quantum state*without incurring*quantum errors*or losing at least some of its*state*over time.*Coherence*of a*quantum computer*is practically characterized by the number of*quantum logic gates*that can be*executed*before*quantum errors*begin to occur, or by the*elapsed time*that it takes that number of*gates*to be executed.*Quantum error correction*(*QEC*) can be used to mitigate*quantum decoherence*. See also:*quantum decoherence*. See the Wikipediaarticle. See also:*Quantum decoherence**fidelity*.**quantum coherence time.**The*elapsed time*before a*qubit*or a*quantum computer*loses*coherence*— the*quantum state*of*qubits*begins to deteriorate. Synonym for*quantum decoherence time*. Shortened as*coherence time*.**quantum communication.**The use of*quantum entanglement*to communicate over a significant distance. Utilizes a*quantum communication channel*and*quantum memory*. See thepaper.*Quantum communication with photons***quantum communication channel.**A communication channel used for*quantum communication*which is capable of transmitting*quantum information*and maintaining its*quantum state*. See the Wikipediaarticle. Shortened as*Quantum channel**quantum channel*. See also:*quantum memory*.**quantum communication system.**See*quantum communication*.**quantum complexity theory.***Computational complexity theory*as applied to*quantum computing*. The study of how much work a*quantum computer*must perform to solve a problem of a given size, and how long it would take the*quantum computer*to complete*execution*of a given*quantum program*which solves the problem. See the Wikipediaand*Quantum complexity theory*articles.*Computational complexity theory***quantum composer.**An interactive software tool which facilitates construction of*quantum logic circuits*and*quantum programs*. The tool itself runs on a*user*’s personal*classical computer*, not the eventual*quantum computer*on which the*circuit*or*quantum program*is intended to*execute*. An example is the, which refers to a created*IBM Q Experience Quantum Composer**circuit*as a*quantum score*.**quantum computation.***Computation*on a*quantum computer*.*Execution*of the*quantum logic gates*of a*quantum program*or*quantum circuit*, based on*quantum code*which implements*quantum algorithms*operating on*quantum bits*(*qubits*), which follow from the*principles of quantum mechanics*, including and especially*superposition*and*entanglement*. The essence of*quantum computation*is the precise control of the*quantum states*of*qubits*. Seeby John Preskill of CalTech. See the Wikipedia*Chapter 6 Quantum Computation*article. Abbreviated as*Quantum computing**QC*.**quantum computational chemistry.**TBD. In contrast to*classical computational chemistry*.**quantum computational chemistry package.**TBD. Such as OpenFermion or Qiskit Aqua.**quantum computational complexity.***Computational complexity*of a*quantum algorithm*or*quantum program*or*quantum circuit*as computed according to*quantum computational complexity theory*.**quantum computational complexity theory.**TBD.**quantum computational cost.**TBD.**quantum computational gate synthesis.**The process of transforming*quantum logic gates*into*control*of the*quantum state*of*qubits*. See thepaper*Control aspects of quantum computing using pure and mixed states***quantum computational supremacy.**See*quantum supremacy*.**quantum computer.**A*machine*or*computer*capable of*quantum computation*. A*machine*exploiting the*principles of quantum mechanics*to perform*computation*in a way that is significantly superior to a*classical computer*. A*computer*in which the basic*unit*of information is a*superposition*of 0 and 1, and supports*entanglement*of*values*. May be either a*physical quantum computer*or a*quantum computer simulator*. Generally, the former. See the Wikipediaarticle. Abbreviated as*Quantum computing**QC*.**quantum computer application.**An*application*for a*quantum computer*.**quantum computer architecture.**The*specification*of the*technology*and major*components*of a*quantum computer*and how they interact. Including number of*qubits*, their*connectivity*, and*quantum logic gates*which are supported. Would also generally include some sense of performance and limitations, such as*coherence*and maximum*circuit depth*.**quantum computers are probabilistic rather than deterministic.**The essential distinction between*quantum computation*and*classical computation*. Based on*quantum mechanics*being*probabilistic*, particularly when*superposition*is being exploited.**quantum computer chip.**An*integrated circuit*which implements one or more*qubits*of a*quantum computer*.**quantum computer design.**A combination of the*instruction set architecture*and the*hardware design*of a*physical quantum computer*. A*quantum computer simulator*will have the former, but not necessarily the latter. Alternatively, the*process*of producing the*design*for a*quantum computer*.**quantum computer engineering.**The adaptation and extension of c*lassical computer engineering*to the design and construction of the*hardware*of*quantum computers*, in contrast to*classical computer engineering*for*classical computers*. Includes the*implementation*of*quantum instruction set architectures*. See also:*quantum computer design*,*quantum science,*and*quantum computer science*.**quantum computer language.**A*programming language*used for*coding*of a*quantum program*or a*quantum circuit*.**quantum computer operation.**Either a single*quantum logic operation*or the physical activity of a*quantum computer*. Alternatively, the human activity needed to keep a*quantum computer*in operation.**quantum computer processor.**The heart of a*quantum computer*. The*quantum computing hardware*of a*quantum computer*which houses the*qubits*and where*quantum logic gates*are*executed*against the*qubits*. May also be referred to as a*quantum information processor*. May informally be referred to as the*quantum processor*, or in context as the*processor*. Alternatively, sometimes used simply as a synonym for the overall*quantum computer*.**quantum computer processor operation.**See*quantum computer operation*.**quantum computer program.**See*quantum program*.**quantum computer science.**Not yet a defined field of its own. Ultimately, an adaptation and extension of*classical computer science*to the theory, design, development, and application of*software*which*executes*on, interfaces with, or otherwise utilizes a*quantum computer*, in contrast to*classical computer science*for*classical computers*. This includes both*quantum programs*and*software*operating in the*hybrid mode of operation*. Includes the*specification*and use of*quantum instruction set architectures*, but not the*implementation*of the*hardware*of a*quantum computer*. See also:*quantum science*and*quantum computer engineering*.**quantum computer simulation.**See*quantum computer simulator*.**quantum computer simulator.**Software which simulates the operation of a quantum computer on a classical computer, simulating the*execution*of a*quantum program*. The*quantum program*will likely run much slower than on a*real quantum computer*. It may also*execute*more correctly, without*decoherence*, since it is not limited by the*physical device*limitations of a*real quantum computer*. See also*high-end quantum computer simulator.***quantum computer system.**Either a reference to a*quantum computer*itself or to the entire*system*, including supporting devices, equipment, apparatus, cabling, shielding, cooling, power, software, etc. See*quantum computing system*.**quantum computing.***Computing*using a*quantum computer*. All of the activities which surround the use of a*quantum computer*, from design of*quantum algorithms*, to development of*quantum programs*, to*execution*on a*quantum computer*, to integration with*classical computing*, to*post-processing*of*measured results*from the*quantum computer*. And the entire*quantum computing ecosystem*. See also:*quantum computation*. Alternatively, includes*design*and*development*of the*quantum computer*itself rather than only the use of the*quantum computer*. Abbreviated as*QC*.**quantum computing algorithm.**An*algorithm*designed to exploit the capabilities of a*quantum computer*. See also:*quantum program*.**quantum computing application.**An a*pplication*which utilizes a*quantum computer*. May be either a synonym for*quantum computing application software*or a*problem*whose*solution*can be achieved using a*quantum computer*.**quantum computing application software.**A*pplication software*which utilizes a*quantum computer*. The combination of one or more*quantum circuits*(*quantum programs*) and one or more*classical computer programs*to orchestrate processing for a complete*software application*. How much of the*application*is*executed*directly on the*quantum computer*vs. a*hybrid mode of operation*will vary.**quantum computing architecture.**The foundation conception and structure of a*quantum computer*in which*computing*is based on the fundamental value*unit*of a*qubit*, which can be simultaneously in a*superposition*of the |0> and |1> states, in contrast to*binary computing architecture*where the value unit is a*binary bit*which has a value of either 0 or 1. [TBD: link to more detail].**quantum computing capabilities.**All*features*and*functions*of a*quantum computer*.**quantum-computing capabilities.**See*quantum computing capabilities*.**quantum computing component.**A*component*which is part of or used with a*quantum computer*. May be a*quantum hardware component*or a*quantum software component*. For example, a*qubit*, a*quantum circulator*, or a*quantum assembler*.**quantum computing concept.**Any*concept*or*principle*related to*quantum computing*, such as*quantum mechanics*,*superposition*,*entanglement*,*quantum logic gate*,*quantum circuit*,*quantum program*,*preparation*,*execution*, and*measurement*, among many others. See also:*quantum computing principles*.**quantum computing device.**Either a*quantum computer*or a*quantum computing hardware component*.**quantum computing ecosystem.**The*computing ecosystem*for*quantum computing*. The technology, tools, support infrastructure, vendors, component suppliers, service suppliers, community, and people. And of course the*quantum computers*themselves.**quantum computing era.**The era or*period of time*which begins with reasonably widespread use of*robust and reliable quantum computers*, when many organizations have access to*commercially-viable quantum computers*. Whether*quantum ready*signals that the era is underway is a matter of debate. Personally, I would say that the very definition of*quantum ready*indicates that*robust quantum computers*are not yet available, indicating that the*quantum computing era*has not yet begun, at least in earnest.**quantum-computing expert.**A*professional*who is widely recognized for their*knowledge*and*expertise*in*quantum computing*.**quantum computing hardware.**The hardware for a*quantum computer*itself. What the vendor will ship when an organization buys a quantum computer. See also:*quantum computing software.***quantum computing platform.**Synonym for*quantum computer*or*quantum computing system*, emphasizing the*features*and how they can be used by*quantum developers*, in contrast to*performance*or other characteristics which are not directly visible to*quantum developers*.**quantum-computing platform.**See*quantum computing platform*.**quantum computing principles.**The principles of*quantum computing*and*quantum mechanics*, especially*superposition*,*entanglement*,*qubits*,*quantum logic gates*,*quantum logic circuits*,*quantum preparation*,*quantum execution*,*quantum measurement*, and*decoherence*. Synonym for*principles of quantum computing.***quantum computing project.**A project or effort which utilizes a*quantum computer*.**quantum computing research.**All aspects of*research*into*quantum computing*, including*principles*,*theory*,*hardware*,*instruction set architecture*,*algorithms*,*fault tolerance*,*software*,*development tools*,*software tools*, and*applications*.**quantum computing software.**All levels of*software*for*quantum computing*. The*full stack*. Operating system, middleware, tools, compilers, editors, packages and libraries, interactive development tools, debugging tools, simulators, analysis tools, etc. And*quantum applications*.**quantum computing solution.***Solution*to a*problem*or*opportunity*which utilizes a*quantum computer*.**quantum computing stack.**See*quantum computing software*.**quantum computing system.**Both the*quantum computing hardware*and*quantum computing software*needed for a*quantum computer*to execute*quantum programs*for users, as well as any additional equipment to support the*system*and connect it to the*Internet*, so that*users*can submit*quantum programs*for*execution*. Synonym for*quantum computer system*.**quantum computing solutions.**Full, end to end solutions to commercial, industrial, and scientific problems, both*quantum computing hardware*and*quantum computing software*. And*quantum computing services*as well.**quantum computing technology.**Any*hardware*or*software*relevant to the design, development, construction, deployment, or use of a*quantum computer*.**quantum computing technology ecosystem.**The*vendors*,*products*, and*services*which enable and facilitate the conception, theory, design, development, construction, deployment, or use of a*quantum computing technology*.**quantum computing theory.**Formalization of the core principles underlying the functioning of a*quantum computer*, specifically*qubits*, with*quantum superposition*and*quantum entanglement*,*quantum logic operations*,*quantum logic circuits*,*quantum logic preparation*,*quantum logic execution*, and*quantum logic measurement*. [TBD: no solid reference yet?]. See the Wikipediaarticle. Synonym is*Quantum computing**theory of quantum computing*. See also:*quantum computing principles*.**quantum computing toolkit.**A collection of*software tools*and*software libraries*which enable and facilitate the*development*of*quantum programs*.**quantum connectivity.**See*quantum entanglement*. See also:*connectivity between qubits*and*connectivity map*.**quantum control.**The*non-quantum hardware*and*firmware*which effects the manipulation of*qubits*, primarily due to*execution*of*quantum logic gates*, such as through*microwave pulses*or*laser pulses*.**quantum controlled phase gate.**TBD. See thepaper by Qin, Wang, Miranowicz, Zhong, and Nori. See also:*Heralded quantum controlled phase gates with dissipative dynamics in macroscopically-distant resonators**controlled phase gate*and*heralded quantum controlled phase gate*.**quantum convolutional layer.**TBD.**quantum core.**The innermost*subsystem*or*chip*(s) of a*quantum computer*which contains the*qubits*. Alternatively, also includes the*subsystem*which contains all of the*control circuitry*and other hardware needed for the*execution*of*quantum logic gates*.**quantum correlation.**TBD. See the Wikipediaarticle.*Quantum correlation***quantum coupling.**See*quantum entanglement*. They are synonyms. See also:*qubit coupling*.**quantum cryptographic algorithm.**See*quantum cryptography*.**quantum cryptographic method.**See*quantum cryptography*.**quantum cryptography.**The use of a*quantum computer*to perform tasks associated with*cryptography*, including*quantum key distribution*,*encryption*,*decryption*, and*quantum communication*. See the Wikipediaarticle. See also:*Quantum cryptography**post-quantum cryptography*. Alternatively, the use of a*quantum computer*to*crack a cryptographic key*. See also:*traditional modern cryptography*.**quantum data.**See*quantum information*.**quantum data processing inequality.**TBD.**quantum decoherence.**The tendency of a*quantum computer*to lose its*quantum coherence*due to*quantum errors*, typically due to poor*isolation*from the*surrounding environment*. The*coherence*of a*quantum computer*is practically characterized by the number of*quantum logic gates*which can be*executed*before*quantum errors*begin to occur, or by the*elapsed time*that it takes that number of*gates*can be executed.*Quantum error correction*(*QEC*) can be used to mitigate*quantum decoherence*. See also:*quantum coherence*. See the Wikipediaarticle. [TBD: expand, add detail, cleanup.] See also:*Quantum decoherence**fidelity*. See also:*quantum coherence time*and*quantum decoherence time*.**quantum decoherence time.**The*elapsed time*before a*qubit*or a*quantum computer*loses*coherence*— the*quantum state*of*qubits*begins to deteriorate. Synonym for*quantum coherence time*. Shortened as*decoherence time*.**quantum decryption.**The use of a*quantum computer*to*decrypt messages*.**quantum developer.**A*software developer*or other*computer professional*, or possibly a*scientist*or*engineer*, who engages in the*development*of*quantum programs*or*quantum logic circuits*based on*quantum algorithms*, which they may or may not have*designed*or*adapted*themselves. Usually a member of a*project*and a*team*.**quantum development.***Development*of*quantum programs*and*quantum logic circuits*.**quantum development environment.***Software tools*for*quantum development*. For example,from Rigetti Computing.*Forest***quantum device.**Synonym for*quantum computer*, the raw machine, the hardware. Alternatively, an individual*qubit*.**quantum device engineer.**TBD.**quantum devices without error correction.***Quantum computers*which do not employ any scheme to mitigate*quantum errors*. That makes them simpler and faster, but less reliable. This is generally not by choice, but usually the only*quantum technology*which is available. The common case in 2018.*Quantum error correction*(*QEC*) is still limited to the*research stage*. Alternatively, an individual*qubit*, emphasizing that it has no*quantum error correction*.**quantum dot.**A very small*semiconductor particle*exhibiting behavior in between larger*semiconductor components*and*discrete molecules*. See the Wikipediaarticle. Abbreviated as*Quantum dot**QD*. See*depletion mode quantum dots*and*enhancement mode quantum dots*.**quantum dot cellular automata.**A*quantum computer*based on a grid or lattice of*quantum dots*(*QD*). See the Wikipediaarticle. See the*Quantum dot cellular automaton*paper.*Quantum Computing with Quantum-dot Cellular Automata using Coherence Vector Formalism***quantum dot cellular automaton.**See*quantum dot cellular automata.***quantum dot quantum computer.**A*quantum computer*based on*quantum dots*(*QD*). See also*scalable quantum dot quantum computer*. Abbreviated as*QDQC*. See thepaper by Loss and DiVincenzo.*Quantum Computation with Quantum Dots***quantum dot technology.**Any device based on*quantum dots*(*QD*).**quantum ecosystem.**See*quantum computing ecosystem*.**quantum eigenvalue estimation algorithm.**See*quantum phase estimation algorithm*.**quantum enabled project.**See*quantum-enabled project*.**quantum-enabled project.**A*program*,*application*, or*system*which uses*quantum algorithms*and the*execution*of*quantum programs*or*quantum logic circuits*on a*quantum computer*for some portion(s) of its*computation*. See also:*hybrid mode of operation*.**quantum encryption.**The use of a*quantum computer*to*encrypt messages*and/or*decrypt messages*. Alternatively, to use a*quantum computer*to*crack an encrypted message*.**quantum energy level.**The*energy*level of a*quantum system*can take on only*discrete*quantities of*energy*, a*discrete level*— the*ground state*or an*excited state*. See the Wikipediaarticle.*Energy level***quantum-enhanced feature space.**TBD.**quantum enhanced feature space.**See*quantum-enhanced feature space*.**quantum entanglement.**Two (or more)*qubits*(or any*particles*for*quantum mechanics*in general) have a combined, shared, common*quantum state*(*entangled state*) as if they were a single*quantum system*and do not have an independent*quantum state*for each*qubit*(or particle.) Measurement of an*observable*of either*qubit*or*particle*will necessarily give a value that is identical to that same*observable*of the other*qubit*(or particle.) Commonly achieved by a combination of a*Hadamard gate*(*H gate*) and a*controlled-NOT gate*(*CNOT gate*) — see*entangle two qubits*. See the Wikipediaarticle. See also:*Quantum entanglement**entangle two qubits*,*connectivity between qubits*, and*connectivity map*.**quantum entanglement detection.**Any method used to detect that the*quantum states*of two*qubits*are*entangled*. See*quantum entanglement*. See thepaper.*Entanglement detection***quantum entanglement witness.**A*technique*to examine whether a*qubit*is*entangled*or not. See the Wikipediaarticle.*Entanglement witness***quantum error.**Any deviation from the proper*quantum state*for a particular*qubit*or the*quantum computer*as a whole (all*qubits*). This may be due to*decoherence*or*stray electromagnetic radiation*if the machine is not properly*isolated*from the*surrounding environment*. See also:*quantum decoherence*. See also:*quantum error correction (QEC)*. [TBD: expand, more detail, link.]**quantum error correcting code.**See*quantum error-correcting codes*.**quantum error-correcting codes.**Additional*qubits*in a*quantum computer*used to compensate for*quantum errors*roughly analogous to*Error-Correcting Code (ECC)*memory on a*classical computer*. Shortened as*QECC*.**quantum error correction (QEC).**Various techniques to compensate for*errors*in the*quantum state*of a*qubit*due to*decoherence*or*stray electromagnetic radiation*, such as adding*code qubits*— see*quantum error-correcting codes (QECC)*. See the Wikipediaarticle.*Quantum error correction***quantum error-correction scheme.**See*quantum error correction*.**quantum error mitigation.**Techniques for designing*quantum circuits*to compensate for*qubit errors*and*gate errors*. Abbreviated as*QEM*. See also*quantum error correction*(*QEC*).**quantum error mitigation scheme.**See*quantum error mitigation*.**quantum error mitigation technique.**TBD. Abbreviated as QEM.**quantum error rate.**The probability that an*error*will occur when*executing*a*quantum logic gate*or*operation*. 1 in 1,000 or 0.001 for*single-qubit operations*and 1 in 100 or 0.01 for*two-qubit operations*is common with*quantum computers*as of July 2018.**quantum execution.**May be either*quantum logic gate execution*,*quantum circuit execution*, or*quantum program execution*.**quantum execution phase.**The stage of processing of a*quantum circuit*or*quantum program*when*execution*is performed —*quantum logic circuit execution*. See also:*quantum preparation phase*and*quantum measurement phase*.**quantum experiment.**An*experiment*run on a*quantum computer*.**quantum factorization.***Prime factorization*using a*quantum computer*. Such as to*crack an encryption key*. See thepaper by Dattani and Bryans. See also:*Quantum factorization of 56153 with only 4 qubits**Shor’s algorithm*.**quantum fault-tolerance theorem.**See*quantum threshold theorem*.**quantum fault.**See*quantum error*. There are three stages of*execution*during which*quantum faults*may occur:*preparation*,*logic gate execution*, and*measurement*. See*faulty quantum logic preparation*,*faulty quantum logic gate execution*, and*faulty quantum measurement*.**quantum fidelity.**See*quantum coherence*.**quantum field theory.**The theoretical framework in theoretical physics that combines classical field theory, special relativity, and*quantum mechanics*. See the Wikipediaarticle. Abbreviated as*Quantum field theory**QFT*(which may be confused with*quantum Fourier transform*.)**quantum finite-state automaton.**Adaptation of the concept of a*finite-state automaton*to*quantum computing*. Abbreviated as*QFA*.**quantum finite-state machine.**Adaptation of the concept of a*finite-state machine*to*quantum computing*. See also:*quantum finite-state automaton*.**quantum Fourier transform.**The*discrete Fourier transform*adapted to*quantum computation*. See the Wikipediaarticle. Abbreviated as*Quantum Fourier transform**QFT*. See also:*approximate quantum Fourier transform*,*banded quantum Fourier transform*, and*full quantum Fourier transform*.**quantum future.**Vague, general reference to future years when*quantum computing*is common and*quantum computers*are relatively cheap and relatively plentiful, or at least significantly more practical than they are today. A time when it is not uncommon for your average Fortune 500 company to be using*quantum computing*on a regular and consistent basis. Not necessarily implying that*classical computing*will have waned to any significant degree. Alternatively, the point where*classical computing*is essentially fully eclipsed by*quantum computing*, but not likely soon.**quantum gate.**See*quantum logic gate*.**quantum gate array.**Synonym for*quantum logic circuit*(*quantum circuit*) or*quantum program*. Term used by Shor in.*Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer***quantum gate library.**See*quantum logic gate library*.**quantum gate sequence.**See*quantum logic circuit*.**quantum gate set.**See*quantum instruction set*. Alternatively, [TBD: review literature].**quantum gate set tomography.**TBD. Abbreviated as*GST*.**quantum grammar.**The adaptation of the concept of a*language**grammar*to*quantum computing*. [TBD: more detail] See thepaper. See also*Quantum Automata and Quantum Grammars**quantum automata*and*quantum language*.**quantum hardware.**The*physical hardware*of a*quantum machine*,*quantum device*, or*quantum computer*. Alternatively, the*hardware*for the*qubits*alone, possibly including the*hardware*which directly*manipulates*the*qubits*(*quantum control*), and possibly the*hardware*for*quantum logic gate execution*, separate from all of the other*hardware*of a*quantum computer*.**quantum hardware component.**A*hardware component*which is part of or used with a*quantum computer*, in contrast to a*quantum software component*. For example, a*qubit*or a*quantum circulator*. Alternatively, only the*hardware*for the*qubits*themselves, and possibly the*hardware components*which directly*manipulate*the*qubits*and for*quantum logic gate execution*.**quantum hybrid algorithm.***Algorithm*which is split into portions which are*classical algorithms*and portions which are*quantum algorithms*, so that portions utilize a*classical computer*and portions utilize a*quantum computer*. See*hybrid mode of operation*. Synonym for*quantum/classical hybrid algorithm*.**quantum information.***Data*or*information*which is held in the*quantum state*of a*quantum system*— the*qubits*of a*quantum computer*. See the Wikipediaarticle. Alternatively, both*Quantum information**quantum computing*and*quantum communication*.**quantum information application.**See*quantum computer application*.**quantum information processing.**See*quantum computation*.**quantum information processing algorithm.**See*quantum algorithm*. Essentially, all*quantum information processing*is*quantum computation*.**quantum information processor.**Synonym for*quantum computer*. Alternatively, may be emphasizing only the core processing logic of the*hardware*(the*quantum computer processor*or*quantum processor*) where*logic gates*are*executed*against*qubits*.**quantum information research.**All aspects of*research*into*quantum information*— both*quantum computing*and*quantum communication*. Includes*theory*,*hardware*,*instruction set architecture*,*algorithms*,*fault tolerance*,*software*,*development tools*,*software tools*, and*applications*.**quantum information research community.**All*quantum information researchers*.**quantum information researcher.***Professional*engaged in*quantum information research*. Member of the*quantum information research community*.**quantum information science.***Information science*adapted to*quantum computing*. Representing, storing, transmitting, manipulating, creating, transforming, and monitoring information in*devices*and*media*which require*quantum mechanics*to fully explain their behavior. See the Wikipediaarticle. See also:*Quantum information science**quantum information theory*.**quantum information science and engineering.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and engineering field.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and engineering research.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology activities.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology applications.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology industry.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology research.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology research and development.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology research and development programs.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology research and education.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology research, testing, and education.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information science and technology workforce.**TBD. Referenced inbill. See also:*National Quantum Initiative Act**quantum information workforce*.**quantum information science and technology workforce pipeline.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum information scientist.**TBD.**quantum information theorist.***Quantum researcher*working in the area of*quantum information theory*. See also:*quantum information research*and*quantum information researcher*.**quantum information theory.**See*quantum information*. Seeby John Preskill of CalTech.*Chapter 5 Quantum Information Theory***quantum information workforce.***Professionals*working in the field of*quantum computing*. See also:*quantum information science and technology workforce*.**quantum-inspired algorithm.**Short for*quantum-inspired classical algorithm*.**quantum-inspired classical algorithm.**See*quantum-inspired computing technology*.**quantum-inspired computing.**See*quantum-inspired computing technology*.**quantum-inspired computing technology.**Attempting to apply some of the concepts from*quantum computing*and*quantum algorithms*to the development of*algorithms*designed to*execute*on*classical computers*, beyond merely*simulating a quantum computer*. The*goal*is to achieve either greater performance or the capacity to handle larger problems than with*classical algorithms*, or to achieve results that*classical algorithms*have not been capable of achieving. There is also potential for enhancement of classical*computing hardware*to better support*quantum-inspired computing*, possibly using*GPUs*and*FPGAs*. Not all*quantum computing concepts*can be migrated to*classical systems*, but there is still some potential. This is more of an aspirational concept at this stage than a practical reality. Related terms are*quantum-inspired algorithm*,*quantum-inspired classical algorithm*, and*quantum-inspired computing*. See also:*Ewinization*.**quantum instruction language.**An*assembly language for quantum computers*. Abbreviated as*QUIL*. Developed by Rigetti Computing. See thepaper by Smith, Curtis, and Zeng.*A Practical Quantum Instruction Set Architecture***quantum instruction set.**The*instruction set*or types of*quantum logic gates*of a*quantum computer*. See*quantum instruction set architecture*.**quantum instruction set architecture.**A*detailed specification*of the*instruction set architecture*of a*quantum computer*, which is the set of*gates*,*operations*, or*instructions*that a*quantum 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. At present,*qubits*are the only resources available for access. See also*classical instruction set architecture*. For an example see thepaper from*A Practical Quantum Instruction Set Architecture**Rigetti Computing*.**quantum integrated circuit.***Integrated circuit*comprised of one or more*qubits*(*qubit circuits*). Synonym for*qubit chip*. See also:*non-planar quantum integrated circuit*.**quantum interference.**TBD.**quantum interference circuit.**TBD.**quantum interferometric computation.**TBD. Abbreviated as*QUIC*. Referenced inpaper by Shiekh.*The role of Quantum Interference in Quantum Computing***quantum intermediate measurement.***Quantum measurement*performed before the completion of a*quantum circuit*. The*outcome*of the*quantum intermediate measurement*may be used to influence the choice of what*quantum logic gates*will follow.**quantum kernel method.**TBD.**quantum key distribution.**A*method*and*protocol*based on*quantum mechanics*for producing and exchanging*cryptographic keys*between two parties so that they can*communicate*securely. Abbreviated as*QKD*. See the Wikipediaarticle. See also:*Quantum key distribution**quantum communication*.**quantum language.**The adaptation of the concept of a*language*to*quantum computing*. [TBD: more detail] See thepaper. See also*Quantum Automata and Quantum Grammars**quantum automata*and*quantum grammar*. Alternatively, a*quantum programming language*.**quantum latency.**TBD.**quantum leap.**The significant advantage that*quantum computing*is perceived to have over*classical computing*in terms of*performance*and*capacity*, or at least is expected to have once*research*is completed and*practical*obstacles are addressed.**quantum learning.**See*quantum machine learning*.**quantum-like.**An*approach*which is similar or analogous to*quantum*. Exhibiting at least a passing resemblance to the*principles of quantum computing*, such as*quantum states*,*superposition*, and*entanglement*. See also*quantum-inspired*.**quantum-limited amplifier.**TBD. See the IBM Qweb page. Abbreviated as*Rising above the noise: quantum-limited amplifiers empower the readout of IBM Quantum systems**QLA*.**quantum logic.**Any combination of*quantum logic gates*(or*quantum logic operations*) designed to perform some*computation*, ranging from a single*gate*(*operation*), to a*sequence of gates*(*operations*), to a full*circuit*(*quantum logic circuit*) or even a full*program*(*quantum program*). In contrast to*classical logic*. Alternatively, a synonym for*quantum algorithm*.**quantum logic circuit.**A sequence of*quantum logic gates*specifying*quantum logic operations*to be applied to the*qubits*of a*quantum computer*in the order specified. See also*quantum program*. Sometimes referred to as a*gate sequence*or a*quantum gate array*. The*quantum*equivalent of a*code fragment*for a*classical computer*, although it may indeed be equivalent to a complete*classical program*.**quantum logic circuit abstraction.**The conception of a*quantum logic circuit*and its operation, as distinct from its physical or simulated realization. The abstract process of*executing*a*quantum logic circuit*, from*generation*, to*preparation*, to*execution*, to*measurement*, and finally to*post-processing of results*.**quantum logic circuit depth.**The number of*quantum logic gates*in a*quantum logic circuit*. Synonym for*quantum logic gate count*,*circuit depth*, or*gate count*. The length of a*quantum program*.**quantum logic circuit execution.***Execution*of a*quantum logic circuit*on a*quantum computer*, either a*real quantum computer*or a*simulated quantum computer*, each*quantum gate*of the*logic circuit*is*executed*in the order specified. The*circuit*may be a complete*quantum program*, or in the case of*hybrid mode of operation*, it may be only a portion of a larger collection of*circuits*which require intervention by*classical code*before*execution*can continue. May be referred to as*quantum execution*,*circuit execution*, or simply*execution*. See also:*quantum logic gate execution*.**quantum logic circuit fidelity.**A measure of*logic gate errors*during the*execution*of a*quantum circuit*. See also:*cross entropy*. For detailed math, see thepaper. Shortened as*Characterizing Quantum Supremacy in Near-Term Devices**quantum fidelity*or even*fidelity*.**quantum logic circuit generation.**Generation of a*sequence of quantum logic gates*from a*higher-level language*or*intermediate representation*of a*quantum logic circuit*or a*quantum program*. Also referred to as*quantum circuit generation*or simply*circuit generation*. Once generated, the circuit is ready for*execution*.**quantum logic circuit intermediate representation.**A*data format*(*code format*) which represents the*abstract logic*of a*quantum circuit*, but distinct from the exact*code format*required for*execution*on a*quantum computer*. This allows*software tools*to perform various*transformations*on the*code*in this*code format*before it is finally ready for*execution*. See also:*intermediate representation*and*intermediate format*.**quantum logic circuit measurement.**Additional*gates*placed at the end of a*quantum logic circuit*to*measure*the*quantum state*of the*qubits*, to select the subset of the quantum state which is considered the*results*of the circuit. See also:*quantum logic circuit preparation*.**quantum logic circuit preparation.**Additional*quantum logic gates*placed at the beginning of a*quantum logic circuit*to initialize the*quantum state*of the*qubits*which are the*inputs*to the main*logic*of the*circuit*. See also:*quantum logic circuit measurement*.**quantum logic circuit step.**An individual*quantum logic gate*or*operation*in a*quantum logic circuit*or*quantum program*. The*circuit*is a*sequence of steps*.**quantum logic gate.**A single*quantum logic operation*to be performed on one or two*qubits*, or on all*qubits*of a*quantum register*in parallel. A specification of a specific*quantum logic operation*. The basic, building block,*unit*of*execution*in a*quantum computer*. A*sequence of quantum logic gates*are combined into*quantum circuits*to form*quantum programs*. In contrast to*classical logic gates*, which are*physical logic gates*, a*quantum gate*is simply an*operation*rather than a*physical gate*. Commonly shortened to*quantum gate*,*logic gate*, or*gate*. The common*quantum logic gates*are*controlled (cX cY cZ) gate*,*controlled-NOT (CNOT) gate*,*Deutsch (D-theta) gate*,*Fredkin (CSWAP) gate*,*Hadamard (H) gate*,*Ising (XX) gate*,*Pauli-X gate*,*Pauli-Y gate*,*Pauli-Z (R-pi) gate*,*phase shift (R-phi) gates*,*square root of NOT gate (SQRT NOT)*,*square root of Swap gate ( SQRT SWAP)*, and*swap (SWAP) gate*. See the Wikipediaarticle.*Quantum logic gate***quantum logic gate count.**The number of*quantum logic gates*in a*quantum logic circuit*. Synonym for*quantum logic circuit depth*,*circuit depth*, or*gate count*.**quantum logic gate error.***Execution of a quantum logic gate*(*operation*) fails to give the correct or expected result. Commonly due to*quantum decoherence*or*stray electromagnetic radiation*. See also:*quantum error*.**quantum logic gate execution.***Execution*of a single*quantum logic gate*in a*quantum logic circuit*. This is the*unit*of*execution*on a*quantum computer*. See also:*quantum logic circuit execution*. May be shortened as*logic gate execution*or*gate execution..***quantum logic gate instruction set.**See*quantum instruction set*.**quantum logic gate library.**The collective definitions of any group of*quantum logic gates*, organized in a form to facilitate the*development*,*compilation*, and*execution*of*quantum programs*using those*gates*. See also:*commonly used quantum logic gate library*.**quantum logic gate sequence.**See*quantum logic circuit*.**quantum logic operation.**A*logic operation*for a quantum computer. In contrast to a*classical logic operation*for a*classical computer*.*Quantum logical operations*are specified as*quantum logic gates*, and sequences of them are referred to as*circuits*(*quantum logic circuits*). Synonym for*quantum logic gate*. May be referred to as*quantum operation*, or simply*operation*, or*gate*.**quantum logic subcircuit.**Portion of a*quantum logic circuit*. A sequence of*quantum logic gates*which are part of a larger*quantum logic circuit*. Synonym for*sequence of quantum logic gates*.**quantum logical gate.**See*quantum logic gate*. Alternatively, a*quantum logic gate*being*executed*on a*quantum logical qubit*which is implemented as multiple*quantum physical qubits*for the purpose of*quantum error correction*(*QEC*). A*quantum logic gate*being*executed*on one of those*quantum physical qubits*is considered a*quantum physical logic gate*or*physical logic gate*for short.**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*quantum physical qubits*to implement each*quantum logical qubit*. See also:*quantum logical gate*and*quantum physical gate*. Shortened as*logical qubit*.**quantum machine.**Synonym for*quantum computer*. May intend to emphasize the*hardware*, the*physical machine*.**quantum machine learning.**The*artificial intelligence*concept of*machine learning*, applied to*quantum computing*. [TBD: any special aspects worth noting?]. See the Wikipediaarticle.*Quantum machine learning***quantum machine instruction.**See*quantum logic gate*. Abbreviated as*QMI*.**quantum matrix inversion.**TBD.**quantum machine learning.***Machine learning*(*ML*) on a*quantum computer*. Abbreviated as*QML*. See also:*quantum machine learning algorithm*.**quantum machine learning algorithm.**An*algorithm*for*machine learning*which is*optimized*for the unique*capabilities*of a*quantum computer*. See thepaper by Schuld, Fingerhuth, and Petruccione.*Implementing a distance-based classifier with a quantum interference circuit***quantum measurement.**A request to capture the*quantum state*of one or more*qubits*, by*executing*a*quantum measurement logic gate*(one per*qubit*.) Alternatively, the*result*of such a request. By definition, a*measurement*will be a*real value*. This will cause the*quantum state*of any measured*qubits*to*collapse*, to a discrete, specific*real value*, no longer a*superposition*of*values*, so*measurement*is generally done at the end of a*quantum logic circuit*, since any*superposition*of*quantum states*will be lost. It is effectively a*quantum logic gate*, but is not a true,*reversible quantum logic gate*since there will be no way to recreate the previous*quantum state*solely from the*result*due to collapse of the*wave function*. In terms of*quantum mechanics*,*measurement*returns a*value*which is a*basis state*, |0> or |1>, which is represented by an*eigenvector*of the*eigenstate*of the*wave function*for the*qubit*, with the*eigenvector*chosen based on its*probability*, which is represented by the*amplitude*(*probability amplitude*) of the*eigenvector*which is represented by the*eigenvalue*associated with that*eigenvector*. The*probability*for each*eigenvector*of a*qubit*is the square of the*modulus*of the*complex number*representing the*eigenvalue*, the*amplitude*or*probability amplitude*, for its associated*eigenvector*— the sum of the squares of the*real part*and the*imaginary part*of the*amplitude*. The*probabilities*for each of the*eigenvectors*for a given*qubit*must sum to 1.0, by definition, according to the principle of*unitarity*of*quantum mechanics*. Shortened as*measurement*. Synonym for*quantum readout*. See the Wikipediaarticle. See also:*Measurement in quantum mechanics**quantum intermediate measurement*and*eigenvalues and eigenvectors*.**quantum measurement logic gate.**A*quantum logic gate*used to perform*quantum measurement*.**quantum measurement phase.**The stage of processing of a*quantum circuit*or*quantum program*when*measurement*is performed. See also:*quantum preparation phase*,*quantum execution phase,**quantum intermediate measurement*, and*post-processing phase*.**quantum mechanical entanglement.**Proper term from*quantum mechanics*for what we call*entanglement*or*quantum entanglement*in the context of*quantum computing*.**quantum mechanical transistor.**See*quantum transistor*.**quantum mechanics.**The subfield of*physics*concerned with motion and interactions at the*atomic*and*subatomic*level, including*electromagnetic radiation*or*photons*, where the distinction between*particles*and*waves*overlaps and is more about*probability*than*certainty*and*determinism*. In contrast to*classical or Newtonian mechanics*where*probability*is not needed as*certainty*and*determinism*rule. The*state*of a*quantum system*is defined or modeled as a*wave function*which expresses the*probabilities*of the*values*of every*observable*or*measurable quality*or*quantity*of the*system*, where the system might be a single*atom*, a single*electron*, or a single*photon*.*Wave functions*enable*superposition*of multiple*quantum states*for a single*particle*or*wave*. This is the foundation*science*of*quantum computing*. See the Wikipediaarticle. For a more gentle introduction, see the Wikipedia*Quantum mechanics*article.*Introduction to quantum mechanics**Quantum physics*is a synonym.**quantum memory.***Method*or*device*for storing*quantum information*, especially in conjunction with a*quantum communication channel*. Referenced in thepaper by Humphreys, Kolthammer, Nunn, Barbieri, Datta, and Walmsley. Alternatively, sometimes may include*Continuous-Variable Quantum Computing in Optical Time-Frequency Modes using Quantum Memories**qubits*as well.**quantum metrology.**TBD. See the Wikipediaarticle.*Quantum metrology***quantum mind.**A belief that the behavior of the human mind cannot be explained without the need for*quantum mechanics*to explain the operation of the brain and neurons. Essentially, that the human brain and mind constitute a*quantum computer.*See the Wikipediaarticle. Not to be confused with*Quantum mind**quantum cognition*.**quantum Monte Carlo method.**TBD. Abbreviated as QMC.**quantum network.**The ability to transmit*quantum information*— the*quantum state*of*qubits*between*quantum computers*. See the Wikipediaarticle. See also:*Quantum network**quantum communication*. The concept of*networking quantum computers*is not feasible with*current quantum computers*or*near-term quantum computers*, nor does it seem to be coming any time soon after that, but ultimately it will present some very interesting possibilities.**quantum neural network.**The concept of a*neural network*adapted to*quantum computing*. Abbreviated as*QNN*. See the Wikipediaarticle.*Quantum neural network***quantum noise.**Any electrical, magnetic, electromagnetic, thermal, acoustic, or vibration effect from either the*surrounding environment*or from within a*system or apparatus*itself that has the effect of disrupting the*quantum state*of a*quantum system*, such as the*qubits*of a*quantum computer*. See the Wikipediaarticle. See also:*Quantum noise**decoherence*.**quantum non-demolition.**TBD. Abbreviated as*QND*.**quantum non-demolition measurement.**TBD. Abbreviated as*QND*.**quantum nonlocality.**The ability of two physically separated*quantum systems*, such as two*qubits*, to share their*quantum state*so that they may interact at a distance, such as with*quantum entanglement*. See the Wikipediaarticle.*Quantum nonlocality***quantum operation.**See*quantum logic operation*.**quantum operator.**In*quantum mechanics*, a*matrix*which operates of the*quantum state*of a*quantum system*, producing a new*quantum state*. Mathematically this is simply*matrix multiplication*. Alternatively, a*quantum logic operation*, which effectively represents that*matrix*and effectively implements such a*matrix multiplication*in*hardware*.**quantum optics.***Quantum mechanics*applied to the interaction between*light*(or other*electromagnetic radiation*) and*matter*. See the Wikipediaarticle.*Quantum optics***quantum oracle.**TBD.**quantum order finding algorithm.**See*quantum order-finding algorithm*.**quantum order-finding algorithm.**A*quantum algorithm*to find the*order*of an integer modulo another integer. Also known as the*period*of the integer. The first integer is raised to successive powers until the remainder when divided by the second integer is 1. The order or period of the first integer is the power. Used primarily for factorization of large integers. The basic algorithm can be simply implemented as a*classical algorithm*, but its performance (*computational complexity*) will be exponential (very bad), while the performance of the equivalent quantum algorithm will be polynomial (much better.) This is the core, quantum portion of*Shor’s algorithm*. There are a number of variations on Shor’s original algorithm. In theory, this is the algorithm which will enable a*quantum computer*to crack even the strongest*public-key encryption*. Abbreviated as*QOFA*. See section 5 of thepaper by Shor.*Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer***quantum parallel.**TBD.**quantum parallelism.**Each*quantum logic operation*can be applied to all*quantum states*which are*superimposed*. [TBD: clarify, explain.]**quantum phase estimation.**See*quantum phase estimation algorithm*.**quantum phase estimation algorithm.**Method for calculating an approximation of the*phase*(fraction of a full circle) for a*qubit*. See the Wikipediaarticle. Alternatively,*Quantum phase estimation algorithm**method*for calculation of energy states for*real quantum systems*, such as for*computational chemistry*. Shortened as*phase estimation algorithm*. Abbreviated as*QPE*or*PEA*or*QPEA*. See thepaper by Wang, Higgott, and Brierley. See also:*A Generalised Variational Quantum Eigensolver**variational quantum eigensolver (VQE)*.**quantum phenomena.**See*quantum phenomenon*.**quantum phenomenon.**A*phenomenon*which occurs in a*quantum system*and is due to*quantum mechanics*. Such as*superposition*,*entanglement*,*collapse of quantum state on measurement*, and*coherence*. [TBD: expand]**quantum photonic computing.**TBD. See*quantum photonic processor*. Synonym for*photonic quantum computing*.**quantum photonic processor.**TBD. See also:*on-chip quantum photonic processor*. See thecorporate website.*Xanadu***quantum physical logic gate.**A*quantum logic gate*being*executed*on a*quantum logical qubit*which is implemented as multiple*quantum physical qubits*for the purpose of*quantum error correction*(*QEC*). A*quantum logic gate*being*executed*on one of those*quantum physical qubits*is considered a*quantum physical logic gate*or*physical logic gate*for short. See also:*quantum logical gate*.**quantum physical qubit.**Either the*hardware*implementing a*qubit*or one of a collection of*qubits*which collectively represent a single*quantum logical qubit*for the purpose of*quantum error correction*(*QEC*). See also:*quantum physical logic gate*.**quantum physics.**See*quantum mechanics*. They are synonyms.**quantum physics of coherent superposition and entanglement.**TBD.**quantum physics simulator.**A*simulator*which can*simulate*the*quantum mechanics*(*quantum physics*) of a*physical system*, both of individual*particles*and*waves*, and*interactions*between them. Not to be confused with a*quantum computer*, which is simply using*quantum mechanics*to implement the functions of*quantum logic gates*. That said, in*theory*, even a*quantum computer*could be*simulated*with a*quantum physics simulator*.**quantum post processing.***Processing*(*post-processing*) of*quantum measurements*which occurs on a*classical computer*after completion of*execution*of a*quantum program*on a*quantum program*. See*post-processing phase*.**quantum preeminence.**See*quantum ascendency*,*quantum advantage*, and*quantum supremacy*. The stage at which*quantum computing*is clearly superior to*classical computing*for a reasonably wide range of*applications*. Alternatively, the stage when*quantum computing*is clearly superior to*classical computing*for one or more reasonably wide niche of*applications*, even if short of preeminence across all niches.**quantum preparation.**See*quantum preparation phase*.**quantum preparation phase.**The stage of*processing*of a*quantum circuit*or*quantum program*when*preparation*is performed, the initialization of the*quantum state*of the*qubits*which are the*inputs*to the main*logic*of the*circuit*. See also:*quantum execution phase*,*quantum measurement phase*, and*post-processing phase*. Synonym for*quantum state preparation*.**quantum probabilistic grammar.**A*quantum grammar*, with probabilities for each grammar rule. See thepaper by Stephen Blaha.*Quantum Computers and Quantum Computer Languages: Quantum Assembly Language and Quantum C***quantum probability.**TBD. See*quantum probability theory*. Alternatively, a reference to the*probabilistic*nature of*quantum computing*.**quantum probability theory.**TBD. See thepaper by Swart and the*Introduction to Quantum Probability*paper by Redei and Summers.*Quantum Probability Theory***quantum process tomography.**TBD. Abbreviated as*QPT*. See also*quantum state tomography*and*output state tomography*.**quantum processing unit.**See*quantum processor*. Abbreviated as*QPU*.**quantum processing unit element.**The individual*electronic components*or*electronic devices*which collectively comprise a single*qubit*or entire*quantum processing unit*(or*quantum processor*or even*quantum computer*.) This includes*Josephson junctions*,*superconducting loops*, and*resonators*. Shortened as*QPU element*.**quantum processor.**The heart of a*quantum computer*which houses the actual*qubits*and where*quantum logic gates*are*executed*. More properly referred to as the*quantum computer processor*. Alternatively, it may simply be a synonym for the overall*quantum computer*. See also:*quantum processing unit*.**quantum processor noise.**See*quantum noise*.**quantum program.**The full sequence of*quantum logic gates*in a*quantum circuit*specifying the*sequence of quantum logic operations*to be performed on the*qubits*of a*quantum computer*. Alternatively, for the*hybrid mode of operation*, a larger collection of*quantum circuits*, each of which may be selectively and conditionally*executed*under the control of a*classical computer*controlling the*quantum computer*. A*quantum circuit*begins with*logic gates*which perform*preparation*(*quantum logic circuit preparation*), initializing the*quantum state*of the*qubits*which are the*inputs*to the main*logic*of the*quantum circuit*, and is followed by*logic gates*which perform*measurement*(*quantum logic circuit measurement*), to retrieve the portions of the quantum state which are considered the*results*or*final results*.**quantum program execution.**Execution of a*quantum program*on a*quantum computer*, either a*real quantum computer*or a*simulated quantum computer*. A*program*can be either a single*quantum circuit*or for the*hybrid mode of operation*it can be a larger collection of*quantum circuits*, each of which may be selectively and conditionally executed under the control of a*classical computer*controlling the*quantum computer*. For each*circuit*, each*quantum gate*of the*circuit*is*executed*in the order specified. May be referred to as*quantum execution*,*quantum circuit execution*, or simply*execution*.**quantum programmer.***Software developer*who specializes in*quantum programming*. See also:*quantum algorithm designer*.**quantum programming.**The*design and coding*of*quantum programs*and*quantum logic circuits*. A tedious and difficult*process*at present, except for the most trivial of*quantum programs*. There are a variety of*tools*, but*design*of*quantum algorithms*is the biggest challenge. See also:*quantum programming language*.**quantum programming language.***Programming language*used to express*quantum programs*, detailing the*quantum logic operations*to be performed, although*higher-level constructs*may be used that will be automatically translated into specific*quantum logic operators*, in contrast to a*classical programming language*. A*quantum programming language*may also include traditional*classical computing*features to allow a*hybrid of classical computing and quantum computing*, such as*classical data structures*and*classical control structures*. See the Wikipediaarticle. See the*Quantum programming*paper, vintage 2005, but giving a decent historical perspective.*Quantum Programming Languages Survey and Bibliography***quantum-proof.***Cryptographic methods*which cannot be*cracked*with a*quantum computer*, such as with*Shor’s algorithm*for factoring very large*numbers*such as*public keys*. See also:*post-quantum cryptography*,*quantum-safe*and*quantum-resistant*.**quantum property.**Any of the*physical quantities*or*properties*and*behavior*of a*quantum system*according to the*principles of quantum mechanics*, each of which is an*observable*which can be*detected*or*measured*, including*mass*,*energy*,*velocity*,*linear momentum*,*angular momentum*, and*spin*.**quantum qubit.**Redundant —*quantum bit*or*qubit*.**quantum readout.**Synonym for*quantum measurement*. Shortened as*readout*.**quantum ready.**Primarily a marketing term. Forward-looking organizations are looking at and experimenting with*quantum computing*, even though its is not yet ready for*production deployment*in*real-world applications*, particularly when it comes to*fault-tolerance*. See*quantum readiness*. Alternatively, the second meaning of*quantum readiness*—*current quantum computers*are indeed ready for*general purpose*and*real-world applications*, including*fault-tolerance*. See the IBMblog post.*Getting the World Quantum Ready***quantum random access memory.**Modeling a*random access memory*(*RAM*) on a*quantum computer*. Abbreviated as*qRAM*or sometimes as*QRAM*. See theand*Quantum random access memory*papers by Giovannetti, Lloyd, and Maccone.*Architectures for a quantum random access memory***quantum readiness.**Primarily a marketing term. No, it doesn’t mean that the*technology*of*quantum computing*is ready for*general purpose*and*real-world applications*, including*fault-tolerance*, today, but simply that the*technology*is evolving rapidly and has shown enough promise and enough actual reality, that forward-looking and forward-leaning*organizations*should be starting to ramp up their*learning*,*research*, and*experimenting*with the*nascent technology*so that when the*technology*is eventually actually ready for*general purpose*and*real-world applications*, including*fault-tolerance*, they can be ready with it, rather than being behind the curve. Alternatively, a*metric*for how ready any particular*quantum computing technology*is for actual deployment in*general purpose*and*real-world applications*, including*fault-tolerance*. See the IBMblog post. See also:*Getting the World Quantum Ready**commercial-availability stage*.**quantum register.**A*sequence*of*qubits*considered as a single*unit*, which can represent up to 2 to the*n*distinct*values*simultaneously via*superposition*, where*n*is the number of*qubits*, in contrast to a*classical register*which can represent only a single*value*at any moment out of 2 to the*n*possible*values*. See also:*n-bit quantum register*.**quantum repeater.**TBD. Referenced in thepaper by Nagata, Kuramitani, Sekiguchi, and Kosaka.*Universal holonomic quantum gates over geometric spin qubits with polarised microwaves***quantum representation.**TBD.**quantum research.***Research*in the fields of*quantum computing*and*quantum communication*. See also:*quantum researcher*,*quantum research community*, and*quantum information research*.**quantum research community.**All*quantum researchers*. See also:*quantum information research community*.**quantum research and development.**See*quantum research*. Referenced inbill.*National Quantum Initiative Act***quantum research and education.**TBD. Referenced inbill.*National Quantum Initiative Act***quantum researcher.***Researcher*in*quantum research*. See also:*quantum information researcher*,*quantum information theorist*, and*quantum research community*.**quantum-resistant.**See*quantum-resistant cryptography.***quantum-resistant algorithm.**A*cryptographic algorithm*which cannot be cracked with a*quantum computer*, such as with*Shor’s algorithm*for factoring very large*numbers*such as*public keys*. See*quantum-resistant cryptography.***quantum-resistant cryptography.***Cryptographic methods*which cannot be cracked with a*quantum computer*, such as with*Shor’s algorithm*for factoring very large*numbers*such as*public keys*. See also:*post-quantum cryptography, quantum-safe cryptography*,*quantum-proof*,*quantum-safe*.**quantum-resistant public-key cryptographic algorithm.**See*quantum-resistant algorithm*.**quantum resource.**A capability or physical property of a*qubit*, especially*superposition*and*entanglement*, which can be exploited for*quantum computation*. [TBD:*interference*as well? Anything else? Are*states**resources*as well?*Amplitude*?*Phase*? Also, term should probably refer to exploiting any*quantum mechanical system*, not just a*qubit*and*quantum computation*.]**quantum revolution.**Vague hyperbole, loosely referring to the perceived advantage which*quantum computing*will have over*classical computing*once*research*is complete and*practical*obstacles are overcome. Alternatively, refers to each significant advance in*research*and*practice*for*quantum computing*. See also:*next quantum revolution*.**quantum-safe.**A*cryptographic method*which cannot be cracked with a*quantum computer*, such as with*Shor’s algorithm*for factoring very large*numbers*such as*public keys*. See also:*quantum-safe cryptography, post-quantum cryptography, quantum-resistant cryptography*,*quantum-proof*, and*quantum-resistant*.**quantum-safe cryptography.**A*cryptographic method*which cannot be cracked with a*quantum computer*, such as with*Shor’s algorithm*for factoring very large*numbers*such as*public keys*. See also:*post-quantum cryptography*,*quantum-resistant cryptography*,*quantum-proof*, and*quantum-resistant*.**quantum science.**Not currently a defined field of its own. Still divided between the fields of physics, computer science, and electrical engineering. Alternatively, any and all aspects of the science of physics, computer science, engineering, and mathematics which are focused on and relevant to the theory, design, construction, and application of*quantum computers*. Includes both*hardware*and*software*. See also:*quantum computer science*and*quantum computer engineering*.**quantum score.**A*quantum circuit*or*quantum program*which has been created using a*quantum composer*, such as the.*IBM Q Experience Quantum Composer***quantum search.**TBD. See also:*Grover’s algorithm*.**quantum search algorithm.**TBD. See also:*Grover’s algorithm*.**quantum sensor.**A*device*(*sensor*) capable of detecting or measuring*quantum properties*, such as the*properties*of a single*photon*, a single*electron*, or a single*atom*. See the Wikipediaarticle. See the NIST*Quantum sensor*web page. See the*Quantum Sensors*paper by Degen, Reinhard, and Cappellaro.*Quantum sensing***quantum signal processing.**TBD.**quantum silicon chip.***Implementation*of a*quantum computer*, particularly*qubits*, using*standard silicon semiconductor integrated circuit technology*, nothing exotic. Still requires*superconductor*chilling, so this does not imply operation at room temperature.**quantum simulator.**See*quantum computer simulator*. Alternatively, a*programmable quantum simulator*used to*simulate a physical system*, to simulate the actual*physics*.**quantum simulation.**See*quantum computer simulation*. Alternatively,*programmable quantum simulation*to*simulate a physical system*, to simulate the actual*physics*. For the latter, see thepaper by Brown, Munro, and Kendon.*Using Quantum Computers for Quantum Simulation***quantum simulation algorithm.**An*algorithm*for*quantum simulation*. Context will be required to determine if this is intended as*simulation*of a*quantum computer*or simulation of the*quantum properties*of an arbitrary*quantum system*.**quantum simulation of chemistry.**TBD.**quantum skeptic.**Individual who does not accept the feasibility or practicality of*quantum computers*. Alternatively, an individual who accepts the long-term prospect of*quantum computing*, but not in the next ten or more years. Alternatively, an individual who accepts the potential for both long and*near-term quantum computing*, but simply does not accept claims that such a goal has actually been achieved by current efforts, such as due to too few qubits or insufficient coherence.**quantum software.**Any*software*suitable for use with a*quantum computer*, including*quantum software tools*,*quantum applications*, and*quantum programs*.**quantum software component.**A software*component*which is part of or used with a*quantum computer*. For example, a*quantum assembler*.**quantum software library.**A*software library*of reusable*quantum software components*.**quantum software and machine learning.**See*quantum software and quantum machine learning*.**quantum software and quantum machine learning.**Use of*quantum computation*for*machine learning*and other aspects of*artificial intelligence*. Abbreviated as*QSML*.**quantum software tool.**Any*software tool*suitable for use with a*quantum computer*.**quantum solution.**A*solution*to a*problem*or*opportunity*which applies the*principles of quantum computing*.**quantum source.**TBD.**quantum source of information.**TBD.**quantum speedup.**A somewhat vague term indicating some measure of how much faster a*quantum computer*is, might be, could be, or might eventually be than the best*classical computers*at*solving*a particular*problem*or*class*of*problem*. Alternatively, the degree to which the rate of*computational complexity*for a*quantum algorithm*grows more slowly than a*classical algorithm*for the same*problem*as the size of the*input*grows — that*Big O*for the*quantum algorithm*is smaller than*Big O*for the comparable*classical algorithm*, such as polynomial vs. quadratic, linear vs. polynomial, square root or logarithmic vs. linear, etc. See thepaper by Rønnow, Wang, Job, Boixo, Isakov, Wecker, Martinis, Lidar, and Troyer.*Defining and detecting quantum speedup***quantum stack.**All levels of*quantum computing*, from the lower levels of*hardware*, including the*physics*and*chip design*, to the upper levels of*software*, including*tools*and*applications*. See also:*full-stack quantum*.**quantum state.**The*probability distribution*for every possible*observable and measurable quality*of the*particles*and*waves*in an (*isolated*)*quantum system*. Represented by the*wave function*for the*quantum system*. Each*quantum state*is a*linear combination*of the*quantum basis states*of the*quantum system*, which are |0> and |1> for a*qubit*. A*quantum basis state*will be a*complex vector*on the surface of a*Bloch sphere*. A*quantum state*can be a*superposition*of two*quantum basis states*, each of which will be a*complex vector*in a*Bloch sphere*. Any number of*quantum states*can be combined linearly into multiple*complex vectors*in a*Bloch sphere*. The*modulus*or*magnitude*of each*complex vector*in the*quantum state*is the*amplitude*or*probability amplitude*for that*complex vector*. The*amplitude*(*probability amplitude*) for a*complex vector*in the*quantum state*represents the square root of the*probability*of the*quantum system*being in the*quantum state*represented by the corresponding*basis state*or*basis vector*. The sum of the*probabilities*for all*basis states*or*basis vectors*in the*quantum state*will be 1.0, as required by the principle of*unitarity*. A*linear combination*of two or more*quantum states*will reduce the*amplitude*(*probability amplitude*) applied to each*basis vector*, so that the sum of the*probabilities*(square of the*modulus*of the*amplitude*) for the*basis vectors*remains 1.0, as required for*unitarity*.*Quantum state*can be modeled for individual*qubits*or for all*qubits*of a*quantum computer*, or any subset of*qubits*, for that matter. A*quantum state*whose*complex vector*is on the surface of the*Bloch sphere*is known as a*pure state*— it is simply a rotation of a*basis state*, |0> or |1>. A*quantum state*whose*complex vector*is inside of the*Bloch sphere*is known as a*mixed state*— it is is*linear combination*of*basis states*, which reduces the*amplitudes*for each of the combined*basis states*. See the Wikipediaarticle.*Quantum state***quantum state is entangled.**Whether the*quantum states*of two*qubits*are*entangled*.**quantum state leakage.**TBD.**quantum state preparation.**See*quantum preparation phase*.**quantum state tomography.**TBD. Abbreviated as*QST*. See also*quantum process tomography*and*output state tomography*.**quantum superdense coding.**Achieving a higher density with*quantum communication*by exploiting*quantum entanglement*. See the Wikipediaarticle. See the*Superdense coding*paper by Anne Hillebrand. Also referred to as*Superdense Coding with GHZ and Quantum Key Distribution with W in the ZX-calculus**superdense coding*or*quantum dense coding*.**quantum superposition.**See*quantum superposition principle*.**quantum superposition principle.**The principle of*quantum mechanics*which allows a single*quantum property*to be in more than one*quantum state*at the same time. This is one of the key factors enabling*quantum computers*. It is what permits a*qubit*to have a*value*of both a 0 and a 1 at the same time. See the Wikipediaand*Quantum superposition*articles. Also referred to as simply*Quantum computing**superposition*.**quantum support vector machine.**TBD. Abbreviated as*quantum SVM*.**quantum support vector machine algorithm.**TBD. Abbreviated as*quantum SVM algorithm*.**quantum supremacy.**A*quantum computer*is able to*compute*a*solution*to a particular*problem*when no*classical computer*is able to do so — or at least not in some reasonable amount of time or with a reasonable number of*classical computers*. Does not imply either an advantage or supremacy for any other*problems*beyond the particular*problem*or niche of closely related*problems*. Implies*quantum advantage*. Alternatively,*quantum advantage*across a broad range of*applications*and categories of*computations*, rather than limited to a particular*problem*or niche of closely related*problems*. May also be merely a synonym for*quantum advantage*unless clear from context. A synonym for*quantum computational supremacy*,*quantum preeminence*, or*quantum ascendency*. See the Wikipediaarticle and the*Quantum supremacy*paper by Boixo, et al. See more discussion in the*Characterizing Quantum Supremacy in Near-Term Devices*paper. Also see the definition and discussion in the*What Is Quantum Advantage and What Is Quantum Supremacy?*paper by Preskill.*Quantum computing and the entanglement frontier***quantum supremacy in the presence of errors.**A*quantum computer*may indeed be faster and handle a larger*problem*than a*classical computer*, but*quantum errors*and the overhead needed to mitigate those errors can diminish or even eliminate that*quantum supremacy*, so*quantum supremacy*must take into account the negative impact of*mitigation of errors*. See thepaper by Bremner, Montanaro, and Shepherd.*Achieving quantum supremacy with sparse and noisy commuting quantum computations***quantum supremacy test.**There is no universally agreed upon benchmark test for what exactly constitutes*quantum supremacy*. This paper,, is one proposal for a*Characterizing Quantum Supremacy in Near-Term Devices**quantum supremacy test*. See also:*practical quantum supremacy test*.**quantum SVM.**Short for*quantum support vector machine*.**quantum SVM algorithm.**Short for*quantum support vector machine algorithm*.**quantum system.**In*quantum mechanics*, a collection of*matter*and*energy*,*particles*and*waves*, of interest, to be studied, analyzed, or used for some*purpose*or*effect*. Presumed to be effectively*isolated*from the*surrounding environment*. Such a*system*has a*quantum state*and a*wave function*. A*quantum system*is a*vector space*where every*vector*is a*linear combination*of the*basis vectors*of that*vector space*, with*quantum states*being*vectors*and*quantum basis states*being*basis vectors*. See the Wikipediaarticle. Alternatively, a synonym for*Quantum system**quantum computer*or*quantum computer system*.**quantum technology.**Any*hardware*or*software*needed to develop and build a*quantum computer*or a*quantum communication device*.**quantum technologies.**See*quantum technology*.**quantum teleportation.**Transmission of the*quantum state*of a*quantum system*(a*particle*or*photon*) over some extended distance, typically for*quantum communication*. Sort of a misnomer since the actual*particle*or*photon*is not physically transmitted. See the Wikipediaarticle.*Quantum teleportation***quantum theorist.**TBD.**quantum theory.**See*quantum mechanics*. See also:*quantum computing theory*.**quantum thinking.**Re-thinking classical*problems*to come up with*quantum solutions*.**quantum threshold theorem.**The claim that*quantum error correction*can be successful if the*physical error rate*for*quantum logic gates*is below some threshold. See the Wikipediaarticle. Also known as the*Quantum threshold theorem**quantum fault-tolerance theorem*.**quantum to classical transition.**See*quantum-to-classical transition*.**quantum-to-classical transition.**The boundary or gray zone between*physical systems*which are small enough that*quantum effects*dominate and*systems*which are large enough that*quantum effects*vanish and*classical effects*dominate. Some*quantum effects*may remain even for*systems*of large sizes, and some*classical effects*may be present even for the smallest*systems*.**quantum tomography.**See*quantum state tomography*,*quantum process tomography*, and*output state tomography*.**quantum transistor.**A*transistor*which exploits the principles of*quantum mechanics*. See the Wikipediaand*Tunnel field-effect transistor*articles. See the article on*Quantum tunnelling*by Sandia Labs. See also:*quantum mechanical transistors**Josephson junction*. Alternatively, a loose reference to a*superconducting quantum interference device*(*SQUID*), commonly as more of a marketing term.**quantum tunneling.**In*quantum mechanics*, the potential for a*particle*or*wave*to cross a barrier such as an*insulator*. See the Wikipediaarticle. See also:*Quantum tunnelling**Josephson junction*.**quantum Turing machine.**A hypothetical equivalent of the concept of a*Turing machine*of*classical computing*applied to*quantum computing*. Such a conception has been neither formalized in theory nor*realized*in the lab in any*current quantum computer*or*near-term quantum computer*as of June 2018. See the Wikipediaarticle. See the*Quantum Turing machine*paper by Guerrini, Martini, and Masini. Shortened as*Quantum Turing Machines Computations and Measurements**QTM*. See also:*universal quantum Turing machine*.**quantum utility crossover point.**TBD.**quantum value.**The value of a*qubit*, which may be a*superposition*of 0 and 1, or |0> and |1>, technically, in contrast to the*binary value*of a*classical bit*, which is either 0 or 1.**quantum variational algorithm.**An*algorithm*for simulating a*physical system*on a*quantum computer*, such as*computational chemistry*. See also:*quantum phase estimation algorithm*and*variational quantum eigensolver (VQE)*. See thepaper by Wecker, Hastings, and Troyer.*Towards Practical Quantum Variational Algorithms***quantum virtual machine.**See*quantum simulator*. Abbreviated as*QVM*.**quantum volume.**A method to judge and benchmark the power and usefulness of a*quantum computer*. A*figure of merit*for the power of a*quantum computer*which is independent of the specific physical*technology*used to implement the*hardware*and neutral with respect to the particular*architecture*of the*quantum computer*. See thepaper by Moll, Barkoutsos, Bishop, and Chow, et al of IBM. They propose that the*Quantum optimization using variational algorithms on near-term quantum devices**figure of merit*be based on five factors: 1) number of*qubits*, 2)*connectivity*between*qubits*, 3) number of*logic gates*(*operations*) which can be*executed*before*errors*or*decoherence*become problematic, 4) range of*operations*in the*logic gate instruction set*, and 5) number of*operations*which can be*executed*in parallel. For a brief summary, see the IBMblog post. My note: I see no mention of the speed of*Increase your quantum IQ**executing**logic gates*, which I think should matter a lot.**quantum walk.**TBD. See*continuous-time quantum walk*and*discrete-time quantum walk*. See the Wikipediaarticle.*Quantum walk***quantum walk operator.**TBD.**quantum watchdog.**TBD. Synonym for*quantum Zeno*. Referenced in thepaper by Shor.*Polynomial-Time Algorithms for Prime Factorization and Discrete Logarithms on a Quantum Computer***quantum wave function.**See*wave function*.**quantum world.**See*quantum computing era*. A world in which*quantum computing*in commonplace rather than being a novelty.**quantum Zeno.**See*quantum watchdog*.**quanvolutional.***Quantum computing*equivalent of*convolutional*.**quanvolutional circuit.**TBD.**quanvolutional filter.**TBD.**quanvolutional layer.**TBD.**quanvolutional neural network.**TBD. Abbreviated as*QNN*.**quasi-lumped element resonator.***Electronic component*(*resonator*) used to read a*qubit*, at least on the Rigetti Computing*QPU*. Seedoc. See also:*The Quantum Processing Unit (QPU)**dispersive readout of a qubit*.**quasiparticle.**The complex nature of a*particle*moving through a*solid*, such as an*anyon*, which does not behave as a normal*particle*. Has the potential to be used to construct a*qubit*. See the Wikipediaarticle.*Quasiparticle***qubit.**The fundamental*unit*of*value*in a*quantum computer*, which may be a*superposition*of 0 and 1, or |0> and |1>, technically, in contrast to a*classical bit*, which is either 0 or 1. Shorthand for*quantum bit*. There are four main types of*qubit*at the*hardware level*:*charge qubit*,*flux qubit*,*phase qubit*, and*spin qubit*. A*qubit*has a*dimensionality*of two, meaning its*quantum states*are modeled by a*Hilbert space*(*vector space*) with two*dimensions*, and*n qubits*modeled by a*Hilbert space*with a*dimensionality*of two to the*n*. Alternatively, in the context of*quantum communication*and*quantum teleportation*, the*quantum state*to be*teleported*. See the Wikipediaarticle. See also:*Qubit**qutrit*,*qudit*,*stationary qubit*,*flying qubit*.**qubit anharmonicity.**See*anharmonicity of a qubit*.**qubit bias.**TBD.**qubit calibration.**See*physical qubit calibration*.**qubit capacitance.**TBD.**qubit chip.**An*integrated circuit*which implements one or more*quantum bits*at the*hardware*level. Synonym for*quantum integrated circuit*. See also:*qubit circuit*.**qubit circuit.***Electronic circuit*for one or more*qubits*. Typically on an*integrated circuit*(*quantum integrated circuit*or*qubit chip*).**qubit coherence.**The ability of a*qubit*to maintain its*quantum state*for an extended*period of time*, in contract with*qubit decoherence*, the tendency for the*quantum state*of a*qubit*to deteriorate relatively rapidly. See also:*qubit fidelity*and*quantum coherence*.**qubit connectivity.**How many and specifically which other*qubits*a given*qubit*can be connected to, either to*execute*a*two-qubit gate*or to perform*quantum entanglement*. Alternatively, the aggregate*qubit connectivity*of all*qubits*of a given*quantum computer*. See also:*qubit coupling*.**qubit control.**The physical processes and controlling electronic circuits which enable*quantum logic gates*to be*executed*, resulting in the*manipulation*of the*quantum state*of a*qubit*. Such as the use of*microwave pulses*.**qubit count.**The number of*qubits*in a particular*quantum computer*.**qubit coupling.**See*quantum entanglement*. Two*qubits*which are*coupled*have*quantum states*which are*entangled*.**qubit decoherence.**The inability of a*qubit*to maintain its*quantum state*for an extended*period of time*, in contract with*qubit coherence*, the ability for the*quantum state*of a*qubit*to persist for an extended*period of time*. See*quantum decoherence*.**qubit detuning.**TBD.**qubit fidelity.**See*qubit coherence*,*quantum fidelity*,*quantum coherence*, and*qubit quality*.**qubit fragility.**The susceptibility of a*qubit*to having its*value*, its*quantum state*, disrupted by*quantum decoherence*or*stray electromagnetic radiation (EMR)*.*Shielding*is required. See also:*qubit coherence*,*qubit decoherence*, and*qubit fidelity*.**qubit frequency bias transfer function.**TBD.**qubit layout.**TBD.**qubit nonlinearity.**TBD.**qubit physical representation.**The specific physical*phenomenon*or*device*used to implement a*qubit*at the*hardware*level in a particular*quantum computer*design. See the Wikipediaarticle. There are four main types of*Qubit**qubit*at the*hardware level*:*charge qubit*,*flux qubit*,*phase qubit*, and*spin qubit*.**qubit quality.**An overall measure of how well a*qubit*can perform its intended functions. This includes degree of connectivity to other*qubits*, error rate for*gate execution*,*coherence time*, and speed of*gate execution*. This also includes how long a*qubit*can maintain a*state*of*superposition*or*entanglement*. Distinct from*qubit count*, which is quantity rather than quality.**qubit-qubit coupling.**See*quantum entanglement*and*quantum coupling*.**qubit-qubit coupling strength.**TBD.**qubit-qubit effective frequency shift.**TBD. Referenced indoc by Rigetti Computing.*The Quantum Processing Unit (QPU)***qubit-qubit frequency detuning.**TBD.**qubit readout.**Synonym for*quantum measurement*. Another synonym is*quantum readout*.**qubit readout error.**TBD. May be shortened as*readout error*.**qubit state.***Quantum state*of a*qubit*. Alternatively, each of the*superimposed states*which collectively comprise the*quantum state*of a*qubit*.**qubit technology.**The*hardware*used to*implement*a*qubit*, along with the*theory*behind it, and the*manufacturing processes*needed to produce it.**qubit transition frequency.**TBD. Referenced indoc by Rigetti Computing.*The Quantum Processing Unit (QPU)***qubit witness.**See*quantum entanglement witness*.**qubitization.**TBD.**QUBO.**Initialism for*quadratic unconstrained binary optimization problem*.**QUBO problem.**Short for*quadratic unconstrained binary optimization problem*. Common application for the D-Wave*special-purpose quantum computer*.**qubyte.**A collection of eight independent*qubits*which are used in*quantum computations*as a*quantum register*, as if they were a classical 8-bit*register*, although each*qubit*has its own*quantum state*which may or may not be*entangled*with the*quantum state*of any of the other*qubits*of the*quantum register*or other*qubits*. Alternatively, a single*qubit*capable of being in 256 distinct quantum states simultaneously. Alternatively, eight*qubits*, equivalent to a*byte*on a*classical computer*. This is a contrived, speculative term as there are no*current quantum computers*or*near-term quantum computers*which can process a so-called*qubyte*as other than eight independent*qubits*. Note that this is not a commonly used term, for either or any other meaning — for now, it’s an*improper*term.**qudit.**Like a*qubit*, but with 10 or more discrete*quantum states*, all of which may be*superimposed*. A*qudit*has a*dimensionality*of ten, meaning its*quantum states*are modeled by a*Hilbert space*(*vector space*) with ten*dimensions*, and*n qudits*modeled by a*Hilbert space*with a*dimensionality*of ten to the*n*. Two*qudits*would represent 100 (10 times 10) simultaneous*states*, more than the 64 states which six*qubits*can represent simultaneously. The 1,000 simultaneous*states*of three*qudits*would be comparable to the 1,024 simultaneous*states*of ten*qubits*. See the IEEEarticle. A*Qudits: The Real Future of Quantum Computing?**qudit*has a*dimensionality*of ten, meaning its*quantum states*are modeled by a ten-*dimensional Hilbert space*(*vector space*.). See also:*qutrit*and*qubit*. Technically, a*qudit*can have any*dimensionality*of ten or higher, so read the above as if “ten” were the actual value of “d”, the intended*dimensionality*.**query.**A request for*information*, such as a*database query*. An*expression*of the*criteria*to be used to select the subset of*information*desired.**queue.**A*list*or line with a front or first*item*and an end or last*item*. New*items*are added to the*list*at the end while*items*are removed from the front of the*list*. The*queue*can grow and shrink, allowing addition and removal of*items*to be*asynchronous*, allowing two*processes*to cooperate without a need to be absolutely*synchronized*.**queued-work model.**When potentially many*users*require access to a limited resource, a*queue*must be created and maintained so that requests from*users*must be added to the end of the*queue*and wait until those requests for the resource will be granted as the*queue*is worked off as the requests at the front of the*queue*are removed from the*queue*as they are satisfied.**QUIC.**Initialism for*quantum interferometric computation*.**QUIL.**Initialism for*quantum instruction language*.**qumode.**Equivalent to a*qubit*for a*quantum photonic processor*designed by Xanadu. Information is stored as a continuous variable.**qutrit.**Like a*qubit*or a*qudit*, but with three*quantum states*, |0>, |1>, and |2>, all of which may be*superimposed*. A*qutrit*has a*dimensionality*of three, meaning its*quantum states*are modeled by a*Hilbert space*(*vector space*) with three*dimensions*, and*n qutrits*modeled by a*Hilbert space*with a*dimensionality*of three to the*n*. See also:*qubit*and*qudit*. See the Wikipediaarticle.*Qutrit***QVM.**Initialism for*quantum virtual machine*.

To browse other parts of the glossary:

- Quantum Computing Glossary — Introduction.
- Quantum Computing Glossary — Part 1 — A-C.
- Quantum Computing Glossary — Part 2 — D-G.
- Quantum Computing Glossary — Part 3 — H-P.
- Quantum Computing Glossary — Part 4 — Q. This part.
- Quantum Computing Glossary — Part 5 — R-S.
- Quantum Computing Glossary — Part 6 — T-Z.