Scientists often claim that quantum computers will blow the competition away in the coming years. Now, the world's first head-to-head test has shown they leave regular PCs reeling in their wake.
Quantum computer use the idea of quantum bits, called qubits, that can theoretically take the value of 0 and 1 at the same time — unlike normal digital computers that can only take one state. It's that blurring of 0s and 1s that gives rise to the claims of speed. But while quantum computers sound futuristic, there are already a handful of systems in existence. It's not yet clear that these devices are genuine quantum computers — it's actually impossible to tell whether they genuinely make use of the physics of quantum entanglement when they're running — but they're certainly based on the appropriate theory.
Now, D-Wave, which makes one of these quantum computers, has let Catherine McGeoch of Amherst College, Massachusetts, test it against a "high-end desktop computer". The D-Wave hardware is designed to solve a special kind of optimisation problem, by minimising the solution of a complicated equation — an incredibly common computer science puzzle. New Scientist describes how the competition went:
McGeoch gave each system roughly half a second to find the best solution to a version of the optimisation problem, and repeated the trial with 100 different versions. She then did the experiment for problems involving even more variables and a more complicated equation.
The D-Wave computer found the best solution every time within half a second. The three regular algorithms struggled to keep up for problems with more than 100 or so variables. The best of the three, CPLEX, had to run for half an hour to match D-Wave's performance on the largest problems.
That's 3600 times longer — quite some difference. Of course, it's debatable as to whether it's a fair test: the quantum computer specialises in solving the problem, whereas the PCs are true all-rounders. But when thrown other kinds of problems, the quantum computer did match or outperform the other computers too. Evidence, then, that quantum computers really do kick arse — it just might still be a few years before you lay your hands on one. [New Scientist]