Currently no commercially viable quantum computer exists. While a usable, functional quantum computer may exist in a few months, years, or even a few millenia (or a superposition of these states) we have covered them fairly extensively here at Ars and Nobel Intent. Spurred earlier this year by DWave's claims of having constructed an adiabatic quantum computer we devoted a series of articles to DWave's showing, what an adiabatic quantum computer is, and what types of problem may be solved using one.

One topic we did not dive into is how certain problems might be solved. In the article that discussed what types of problems could be solved using a quantum computer I mentioned a complexity class known as "bounded error, quantum, polynomial time" (BQP). One of the more well known algorithms in BQP that is also important in quantum computing is Shor's algorithm. This algorithm lays out how one can use a quantum computer to factor numbers. Many readers of Ars have a basic understanding of how a traditional computer works; it contains memory that holds numbers and can perform a set of basic arithmetic operations on those stored numbers. Using this, people have come up with many ways to factor numbers but in general they are inefficient. This inherent inefficiency is at the heart of much of computer security today as many of the ideas rely on the fact that it would take a computer an excessively long amount of time to factor very large numbers. As the number you wish to factor grows larger and larger, a traditional computer will take exponentially more time to factor. A quantum computer on the other hand, can do the operation in polynomial time.

The "how" of the quantum computer is beyond the space for this column, but a two-part essay published on the American Mathematical Society's (AMS) website covers just that. Tony Phillips, a professor of mathematics at Stony Brook University, discusses the math behind Shor's algorithm and how it can be carried out on a quantum computer. The astute reader will realize that these articles are the May and June/July essays, respectively, meaning I am a bit late in bringing them to Nobel Intent's audience's attention. Even though they do not represent breaking news, I thought our readers would still find them interesting.