# Elevator Pitch for Quantum Computing

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What do you say when someone asks what a quantum computer or quantum computing is? In 30 seconds or a minute or so. These are my two suggested brief answers — elevator pitches — to the twin questions:

**What is a quantum computer?****What is quantum computing?**

Also included are definitions for the twin questions of:

**What is a practical quantum computer?****What is practical quantum computing?**

And a few additional tidbits, pointers actually, for those actually wanting to dive deeper into quantum computing.

**Caveat:** My comments here are all focused only on *general-purpose quantum computers*. Some may also apply to *special-purpose quantum computing devices*, but that would be beyond the scope of this informal paper. For more on this caveat, see my informal paper:

*What Is a General-Purpose Quantum Computer?*- https://jackkrupansky.medium.com/what-is-a-general-purpose-quantum-computer-9da348c89e71

**Topics discussed in this informal paper:**

- The elevator pitch on quantum computers
- Single sentence definition for quantum computer
- The elevator pitch on quantum computing
- The essence of quantum computing: exploiting the inherent parallelism of a quantum computer
- What is a practical quantum computer?
- What is practical quantum computing?
- Quantum parallelism is the real power of quantum computing
- The quantum computing sector
- For more detail
- And for a lot more detail
- Postscript — recent debate over hype and potential for quantum computing
- My original proposal for this topic

# The elevator pitch on quantum computers

So, what’s a quantum computer?

A *quantum computer* is a specialized electronic device which is able to perform a fairly small calculation on a very large number of possible solution values all at once, producing a solution value in a very short amount of time. This parallel evaluation of a large number of alternatives is known as *quantum parallelism*.

A quantum computer is not a full-blown computer capable of the full range of computation of a classical computer, but is more of a *coprocessor* which can perform carefully chosen and crafted calculations at a rate far exceeding the performance of even the best classical supercomputers.

Quantum computers are still in their infancy, demonstrating rudimentary capabilities, and not even close to being able to address production-scale practical real-world applications and not even close to being ready for production deployment, but are available in limited capacities for prototyping and experimentation, even as significant research continues.

Quantum applications are a hybrid of classical code and quantum algorithms. Most of the application, including any complex logic, is classical, while small but critical and time-consuming calculations can be extracted and transformed into quantum algorithms which can be executed in a much more efficient manner than is possible with even the most powerful classical supercomputers.

# Single sentence definition for quantum computer

A *quantum computer* is a specialized electronic device which is able to perform a fairly small calculation on a very large number of possible solution values all at once using a process known as *quantum parallelism*, producing a solution value in a very short amount of time.

# The elevator pitch on quantum computing

What is *quantum computing*?

Unlike *classical computing* in which one alternative at a time is evaluated, *quantum computing* is able to evaluate a vast number of alternatives all at the same time, in a single computation rather than a vast number of computations. This parallel evaluation of a large number of alternatives is known as *quantum parallelism*.

A *quantum computer* is a specialized electronic device which exploits the seemingly magical qualities of *quantum effects* governed by the principles of *quantum mechanics* to enable it to perform a fairly small calculation on a very large number of possible solution values all at once, producing a solution value in a very short amount of time. This parallel computation on a large number of values is the *quantum parallelism* mentioned above.

A quantum computer is not a full-blown computer capable of the full range of computation of a classical computer, but is more of a *coprocessor* which can perform carefully chosen and crafted calculations at a rate far exceeding the performance of even the best classical supercomputers.

Quantum applications are a hybrid of classical code and quantum algorithms. Most of the application, including any complex logic and handling of data, is classical, while small but critical and time-consuming calculations can be extracted and transformed into quantum algorithms which can be executed in a much more efficient manner than is possible with even the most powerful classical supercomputers.

Quantum computers are still in their infancy, demonstrating rudimentary capabilities, and not even close to being able to address *production-scale practical real-world problems* and not even close to being ready for *production deployment*, but are available in limited capacities for prototyping and experimentation, even as significant research continues.

It may be three to five, seven, or even ten years before *practical quantum computers* are generally available which support *production-scale practical real-world quantum applications* and achieve *dramatic quantum advantage* over classical computing and deliver *extraordinary business value* which is well beyond the reach of classical computing.

# The essence of quantum computing: exploiting the inherent parallelism of a quantum computer

At its essence, *quantum computing* enables a quantum application to exploit the *inherent parallelism* of a quantum computer to evaluate a very large number of potential solutions to a relatively small computation all at once, delivering a result in a very short amount of time.

# What is a practical quantum computer?

As already mentioned, quantum computers are still in their infancy and not ready for practical use. So, what is a practical quantum computer? By definition:

**A practical quantum computer supports production-scale practical real-world quantum applications and achieves dramatic quantum advantage over classical computing and delivers extraordinary business value which is well beyond the reach of classical computing.**

For more detail on practical quantum computers, see my informal paper:

*What Is a Practical Quantum Computer?*- https://jackkrupansky.medium.com/what-is-a-practical-quantum-computer-de9c8c1fa4b8

# What is practical quantum computing?

*Practical quantum computing* is the fruition of quantum computing, when *practical quantum computers* themselves come to fruition, coupled with all of the software, algorithms, applications, and other components of quantum computing.

*Practical quantum computers* are the hardware.

*Practical quantum computing* is the hardware plus all of the software. As well as the community and ecosystem to support it.

The software includes quantum algorithms, quantum applications, support software, and tools, especially developer tools.

Also included are:

**Education.****Training.****Ongoing research.****Consulting.****Conferences.****Publications.****Community.****Ecosystem.**

It may be three to five, seven, or even ten years before *practical quantum computers* are generally available which support *production-scale practical real-world quantum applications* and achieve *dramatic quantum advantage* over classical computing and deliver *extraordinary business value* which is well beyond the reach of classical computing.

# Quantum parallelism is the real power of quantum computing

Forget about individual qubits — little of value can be computed with individual, isolated qubits (other than a random bit value.)

The real power of quantum computing comes from *quantum parallelism* — n entangled and superimposed qubits (no longer isolated) can represent and operate on 2^n distinct values simultaneously while n classical bits can only represent and operate on one of those 2^n distinct values at a time.

**For n = 10, that’s 1,000 distinct values at a time.****For n = 20, that’s a million distinct values at a time.****For n = 30, that’s a billion distinct values at a time.****For n = 40, that’s a trillion distinct values at a time.****For n = 50, that’s a quadrillion distinct values at a time.****And so on.**

That’s the real power of quantum computing — quantum parallelism.

# The quantum computing sector

Some may consider quantum computing to be an *industry* or *field*, but for the purposes of this informal paper I consider *quantum computing* to be a *sector* of the *overall computing industry* — the *quantum computing sector*.

# For more detail

To go beyond the elevator pitches, I have two long but informal papers:

and

They both link to a wide variety of my other informal papers on a wide range of topics for quantum computing.

# And for a lot more detail

And for the bigger — and deeper — picture on quantum computing, here’s my suggested reading list for those attempting to get started in quantum computing:

*What Is Quantum Computing?**What Is a Quantum Computer?**What Is Quantum Information?**What Is Quantum Information Science?**What Are Quantum Effects and How Do They Enable Quantum Information Science?***What Applications Are Suitable for a Quantum Computer?**

I don’t have my own paper on getting started with hands-on quantum programming — the topic is covered quite well by a shelf full on introductory books, but the *IBM Qiskit Textbook* is a decent tutorial after digesting at least an introductory level from my papers listed above:

# Postscript — recent debate over hype and potential for quantum computing

These are some comments I made on a LinkedIn post concerning recent debate over hype and potential for quantum computing…

These are the operant phrases: “at an early stage” and “given time”.

Although the transistor was invented in 1947, the transistor radio wasn’t a viable product until 1954, the first use in a computer wasn’t until 1953, and computers didn’t switch over to transistors from vacuum tubes in a meaningful manner until 1958.

I like to say that quantum computers are roughly at the stage that classical computers were at in the early 1940’s. They’ve yet to have their “ENIAC Moment” (which was in 1946), when a production-scale application for a practical real-world problem became feasible.

We’re in the *pre-commercialization stage* for quantum computing, marked by *research*, *prototyping*, and *experimentation*. That doesn’t mean that commercialization is imminent, but it does mean that research remains a long pole in the tent.

Prototyping is “real”, but it’s not *production scale* or *production deployment*. Except for the singular application of generating true random numbers, which even today’s quantum computers do quite well.

The debates over hype are a mixed bag — some is true, some is a red herring, and some is just par for the course.

I’m fairly confident that the next two to four years will be very telling — I just can’t predict which way. Research can be quite fickle — great ideas can go bust, and mediocre results can lead to great commercial success.

# My original proposal for this topic

For reference, here is the original proposal I had for this topic. It may have some value for some people wanting a more concise summary of this paper.

**Quantum computing elevator pitch.**What is quantum computing, and why should you care? What is it — in theory, ideally? What is it actually today? What is it expected to be by the end of the year? What is it expected to be in two years? What is it expected to be in five years? What is it expected to be in ten years? One or two short paragraphs, or maybe three or four very short paragraphs at most. May need multiple pitches for different audiences. See also:*Single paragraph introduction to quantum computing*.

For more of my writing: ** List of My Papers on Quantum Computing**.