Quantum computing: A cheat sheet

This resource covers the future of computing in the post-transistor age, and the technical hurdles inherent in the pursuit of quantum computing.

Quantum computing—considered to be the next generation of high-performance computing—is a rapidly-changing field that currently receives much more attention in academia than in business. This guide is both an easily digestable introduction to a new paradigm, as well as a "living" guide that will be updated periodically to keep IT leaders in the loop on advances in the science and commercialization of quantum computing.

SEE: Ebook—IT leader's guide to the future of quantum computing (Tech Pro Research)

Executive summary

  • What is quantum computing? Quantum computing is an emerging technology in search of faster computational solutions to problems currently handled by supercomputers.
  • Why does quantum computing matter? Theoretically, quantum computers could be used to crack RSA cryptography, which is commonly used across the internet.
  • Who does quantum computing affect? At present, primarily researchers working in the field of quantum physics and computing.
  • When will quantum computers be released? Limited function quantum computers are available, though there is not yet a clear benefit compared to traditional computers.
  • How do I get a quantum computer? One company sells an early quantum computer, but it's really only useful for specialized workloads.

SEE: All of TechRepublic's cheat sheets and smart person's guides

What is quantum computing?

Quantum computing is an emerging technology that attempts to overcome certain limitations of traditional, transistor-based computers. Transistor-based computers rely on the encoding of data in binary bits—either 0 or 1. Quantum computers utilize qubits, which are vastly different—while it is possible to encode binary data in a qubit, the values are often superpositions, meaning the values are 0 and 1 at the same time. Qubits can also contain up to two bits of binary data in a process called superdense coding. It is theorized that quantum computers would be capable of performing calculations to solve a particular problem faster than traditional computers.

With this technology, computationally-intensive tasks that are at present typically handled by supercomputers—protein folding, for example—can theoretically be performed by quantum computers at a lower energy cost than transistor-based supercomputers. As the technology behind quantum computers matures, it is likely that they will become faster at such tasks than traditional computers, though this requires a significant refinement to quantum processor manufacturing techniques, and new approaches to computer programming that are cognizant of the non-binary properties of qubits.

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Why does quantum computing matter?

In theory, quantum computing would lead to a breakthrough in integer factorization. This would have serious implications for commonly used encryption systems, such as RSA, which employs public-key cryptography. Shor's algorithm demonstrates the technical feasibility of prime factorization, though at present, the largest number factorized using a quantum computer using this algorithm is 21. Due to the prospect of a viable quantum computer in the future, research into lattice-based cryptography—which is not known to be broken by quantum computers—has increased. Quantum computers should be capable of solving computational tasks that are not feasible to perform on traditional computers.

In January 2014, reports indicated that the NSA has spent $79.7 million on a program titled "Penetrating Hard Targets." As part of this program, research has been conducted to build "a cryptologically useful quantum computer." The documents cited in this report indicate that the NSA has not been appreciably more successful than other researchers.

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Who does quantum computing affect?

At present, primarily researchers—various IT companies are investing in research into quantum computing, with Intel providing $50 million in 2015 to the Delft University of Technology and the Dutch Organization for Applied Research, as well as provide engineering support to the effort. IBM, Google, and Microsoft are also leading their own research efforts, with the former announcing in April 2015 a means of simultaneously detecting bit-flip and phase-flip errors, which is a significant step forward in error correction for quantum computing.

IBM has announced the availability of IBM Q, a service through which users can leverage IBM's quantum computing system. Presently, IBM claims that Q is limited to about five qubits, though the company plans to expand to approximately 50 qubits within the next few years. Google is designing a 49-qubit system, which is anticipated to be operational by the end of 2017.

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When will quantum computers be released?

There are two answers to this question: now, and substantially far in the future. The Canadian company D-Wave Systems currently sells a quantum computer named the D-Wave 2000Q, which is also available as a cloud service, however there are significant caveats with that offering. D-Wave advertises this system as having 2000 qubits, though design differences between D-Wave and the rest of the industry make a comparison unuseful. The systems sold by D-Wave are designed specifically for quadratic unconstrained binary optimization, making them unsuitable for integer factorization required for cracking RSA encryption systems. Additionally, the D-Wave 2 (second-generation system) was found to not be faster than traditional computers.

It is possible that quantum computing may be a viable alternative in the future to current transistor-based solutions, though substantial issues in fabrication and mass-manufacturing must be addressed for this to be a viable technology. Among these are the present difficulty of building computers that scale to multiple qubits, the ability to initialize qubits to a predictable value, and easing the means by which qubits can be read.

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How do I get a quantum computer?

D-Wave's 2000Q system costs $15 million to buy outright, though notable buyers include Volkswagen Group and Virginia Tech. In any event, a quantum computer is not something you are likely to find at your local big-box store. However, if your workloads are more general, building and buying a POWER9 deployment is likely a better value. Oak Ridge National Laboratory's SUMMIT supercomputer is a POWER9 and NVIDIA Volta-driven system planned at 4600 nodes, with a computational performance in excess of 40 teraflops per node.

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Image: Jon Heras/Corbis

About James Sanders

James Sanders is a Writer for TechRepublic. Since 2013, he has been a regular contributor to TechRepublic and Tech Pro Research.

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