Quantum computing: The smart person's guide
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- What is it? Quantum computing is an emerging technology in search of faster computational solutions to problems currently handled by supercomputers.
- Why does it matter? Theoretically, quantum computers could be used to crack RSA cryptography, which is commonly used across the internet.
- Who does this affect? At present, primarily researchers working in the field of quantum physics and computing.
- When is this happening? Limited function quantum computers are available, though there is not yet a clear benefit compared to traditional computers.
- How do I get it? One company sells an early quantum computer, but it’s really only useful for specialized workloads.
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.
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.
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.
Who does this affect?
At present, primarily researchers — various IT companies are investing in research into quantum computing, with Intel providing $50 million 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.
When is this happening?
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 2X, though there are significant caveats with that offering. 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 (the preceding model) 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.
How do I get it?
CNET reports that the previous-generation D-Wave 2 costs $15 million, which is a rather hefty price tag for a specialized computer that requires specialized workloads. IBM is the company to watch for a potential competitor to D-Wave Systems. However, if your workloads are more general, building and buying a POWER8 deployment will be a better value right now, particularly as IBM has opened up that platform to other vendors such as Tyan as part of the OpenPOWER Foundation.