Guest essay by Eric Worrall
The Register has published a fascinating video about Quantum Computing, an interview with D-Wave, a company which manufactures what they claim are quantum computing systems.
According to The Register;
It turns out that there are three broad categories of problem where your best bet is a quantum computer. The first is a Monte Carlo type simulation, the second is machine learning, and the third is optimization problems that would drive a regular computer nuts – or, at least, take a long time for it to process.
An example of this type of optimization problem is this: Consider the approximately 2,000 professional hockey players in North America. Your task is to select the very best starting line-up from that roster of guys.
There are a lot of variables to consider. First there’s all the individual stats, like how well they score, pass, and defend. But since hockey is a team sport, you also have to consider how well they work when combined with other specific players. When you start adding variables like this, the problem gets exponentially more difficult to solve.
But it’s right up the alley of a quantum computer. A D Wave system would consider all of the possible solutions at the same time, then collapse down to the optimal set of player. It’s more complicated than I’m making out, of course, but it’s a good layman-like example.
The following is the video of the interview;
A note of caution. Quantum computing is still in its infancy. There is substantial skepticism expressed in some quarters, about what is happening inside the box, about whether the D-Wave system offers a performance advantage over conventional computers.
A team of quantum-computing experts in the US and Switzerland has published a paper in Science that casts doubt over the ability of the D-Wave Two quantum processor to perform certain computational tasks. The paper, which first appeared as a preprint earlier this year, concludes that the processor – built by the controversial Canadian firm D-Wave Systems – offers no advantage over a conventional computer when it is used to solve a benchmark computing problem.
While the researchers say that their results do not rule out the possibility that the processor can outperform conventional computers when solving other classes of problems, their work does suggest that evaluating the performance of a quantum computer could be a much trickier task than previously thought. D-Wave has responded by saying that the wrong benchmark problem was used to evaluate its processor, while the US–Swiss team now intends to do more experiments using different benchmarks.
The abstract of the paper;
The development of small-scale quantum devices raises the question of how to fairly assess and detect quantum speedup. Here, we show how to define and measure quantum speedup and how to avoid pitfalls that might mask or fake such a speedup. We illustrate our discussion with data from tests run on a D-Wave Two device with up to 503 qubits. By using random spin glass instances as a benchmark, we found no evidence of quantum speedup when the entire data set is considered and obtained inconclusive results when comparing subsets of instances on an instance-by-instance basis. Our results do not rule out the possibility of speedup for other classes of problems and illustrate the subtle nature of the quantum speedup question.
Quantum computing in my opinion is a goal worth pursuing. Even if the D-Wave system does not fulfil its promise, this will hardly be the end of the Quantum Computing effort. The goal, of harnessing almost unimaginable computation power, of being able to solve problems which simply can’t be tackled with conventional computers, is simply too attractive to abandon.