A team of researchers from Google’s artificial intelligence labs has published results which it claims demonstrate that its controversial D-Wave quantum computer really works. D-Wave 2X is world’s first commercial quantum computer
D-Wave 2X developed in Mountain View, California
Google bought one of D-Wave’s quantum computers back in 2013. Claimed to be the “world’s first commercial quantum computer,” the device sits at NASA’s Ames Research Center in Mountain View, California, where it’s coded to tackle optimization problems that quantum computers are supposed to be good for. In theory, D-Wave’s hardware is supposed to be lightning fast—potentially 3,600 times faster than a supercomputer.
D-Wave’s machines are the closest thing we have today to quantum computing, which works with quantum bits, or qubits — each of which can be zero or one or both — instead of more conventional bits. The superposition of these qubits enable machines to make great numbers of computations to simultaneously, making a quantum computer highly desirable for certain types of processes.
In two tests, the Google Quantum Artificial Intelligence Lab today announced that it has found the D-Wave machine to be considerably faster than simulated annealing — a simulation of quantum computation on a classical computer chip.
Google director of engineering Hartmut Neven went over the results of the tests in a blog post today:
We found that for problem instances involving nearly 1,000 binary variables, quantum annealing significantly outperforms its classical counterpart, simulated annealing. It is more than 108 times faster than simulated annealing running on a single core. We also compared the quantum hardware to another algorithm called Quantum Monte Carlo. This is a method designed to emulate the behavior of quantum systems, but it runs on conventional processors. While the scaling with size between these two methods is comparable, they are again separated by a large factor sometimes as high as 108.
Quantum computers can, theoretically, be so much faster because they take advantage of a quirk in quantum mechanics. While classical computers use bits in 0 or 1, quantum computers use “qubits” that can exist in 0, 1 or a superposition of 2. In turn, that allows it to work through possible solutions more quickly.
But D-Wave’s chips have proved controversial. Teams of researchers have been unable to prove whether or not the computer actually takes advantage of true quantum effects.
Now, the team from Google has published results on the arXiv server that it claims demonstrate that the computer does indeed use quantum effects to solve problems at speed. In a series of experiments, the team pitted its D-Wave quantum computer against a regular computer with a single processor and had them race through optimization problems known as annealing.
The regular computer used a technique known as simulated annealing, while the quantum computer used what’s unsurpsingly known as quantum annealing. Google explains what happened:
We found that for problem instances involving nearly 1000 binary variables, quantum annealing significantly outperforms its classical counterpart, simulated annealing. It is more than 10^8 times faster than simulated annealing running on a single core. We also compared the quantum hardware to another algorithm called Quantum Monte Carlo. This is a method designed to emulate the behavior of quantum systems, but it runs on conventional processors. While the scaling with size between these two methods is comparable, they are again separated by a large factor sometimes as high as 10^8.
D-Wawe is 100 million times faster than regular computers
That looks like a convincing victory, with the D-Wave quantum computer completing the task 100 million times faster than the regular computer.
It may not quite be time to pop the champagne corks yet, though. First, the research is yet to be peer-reviewed. Second, as Technology Review points out, even if the results are verified, they overlook the fact that the regular computer wasn’t using the most efficient algorithm it could. It was using a technique that was algorithmically similar to the one running on the quantum computer, but an alternative approach could potentially have let it run through its calculations faster.
The Google team points out that the potential for the regular computer to run faster wouldn’t extend as the problems grew in size in the future. That’s why it chose to compare the two algorithms it did. But for now, the new claims still seem likely to be disputed by quantum physicists.
But Google continues to work with NASA on quantum computing, and meanwhile Google also has its own quantum computing hardware lab. And in that initiative, Google is still in the early days.
“I would say building a quantum computer is really, really hard, so first of all, we’re just trying to get it to work and not worry about cost or size or whatever,” said John Martinis, the person leading up Google’s hardware program and a professor of physics at the University of California, Santa Barbara.
Commercial applications of this technology might not happen overnight, but it’s possible that eventually they could lead to speed-ups for things like image recognition, which is in place inside of many Google services. But the tool could also come in handy for a traditional thing like cleaning up dirty data. Outside of Google, quantum speed-ups could translate into improvements for planning and scheduling and air traffic management, said David Bell, director of the Universities Space Research Association’s Research Institute for Advanced Computer Science, which also works on the D-Wave machine at NASA Ames