Quantum Or Not, New Supercomputer Is Certainly Something Else
Originally published on Wed May 22, 2013 9:33 am
It's exactly the sort of futuristic thinking you'd expect from Google and NASA: Late last week, the organizations announced a partnership to build a Quantum Artificial Intelligence Lab at NASA's Ames Research Center.
But questions surround the new type of computer at the lab's core. D-Wave systems, the company that makes the machine, says it is a quantum computer — a machine that runs on the strange laws of quantum mechanics. But although the computer can solve a certain type of problem much faster than conventional computers, critics say that the company's claims are not supported by scientific evidence.
"It's not exactly science, what they're doing," says Christopher Monroe, a physicist with the Joint Quantum Institute at the University of Maryland. "It's high-level engineering, and I think it's high-level salesmanship, too."
The quantum computer is a giant black box, or more precisely, a black cube approximately 10 feet on a side. Inside is a refrigeration system that chills the guts to near absolute zero, and shields the workings to protect them from external radiation.
In this rarefied environment, the laws of quantum mechanics can come into effect. These quantum rules are pretty strange. Particles can be in two opposite states at once, and they can be intrinsically tied together through a process known as "entanglement." For example, two quantum coins could be in a state of heads and tails simultaneously, as though they were flipping through the air. If the two coins were entangled, reading "heads" on one after the flip would instantly tell you that the other was heads — even if it were on the other side of the galaxy.
The D-Wave Two computer has 512 quantum "bits," or units of information, in its supercooled central processor that can be entangled together, according to the company. The entanglement allows the computer to do things that a conventional computer can't. In particular, it's good at choosing between many different solutions to a problem, according to Geordie Rose, D-Wave's chief technology officer.
Here's (roughly) how it works: Just like quantum coins, the quantum bits exist in two states at once, and because they are entangled, that means the entire chip is simultaneously in many different configurations of "heads and tails." The quantum computer, in a sense, simultaneously tries every answer imaginable before settling on an efficient one. Running the computer just a few times will give a subset of highly efficient solutions. By contrast, a conventional computer would have to individually test millions or billions of solutions to find the right answer.
Rose says that the new machine won't always be better than a regular computer, but for machine learning and searching — activities both Google and NASA are interested in — the D-wave's computer could be far more effective.
"The best answer, or the highest or the lowest or the smallest or the meatiest ... no matter what," Rose says. "If it's got an '-iest' at the end and you can write down a mathematical equation for what you mean about that, then you can attack it with one of our machines."
But proving exactly what D-Wave's computer does is tricky. Quantum states are highly sensitive to outside intrusion. The very act of trying to measure entanglement can easily destroy it.
There is solid evidence that the D-Wave machine is unusual. New research by computer scientist Catherine McGeoch at Amherst College suggests it can solve one particular kind of problem thousands of times faster than a regular computer. But McGeoch adds that the D-Wave Two was not measurably faster at solving two other types of problems tested.
And work from the lab of John Martinis, a researcher at the University of California, Santa Barbara, also seems to hint at quantum processes at work inside D-Wave's previous generation of quantum chip, the D-Wave One.
But Monroe remains skeptical. He believes that the D-Wave team has never demonstrated that entanglement is happening on the chips in its machine. He believes that D-Wave's supposedly quantum bits are actually working instead as tiny electromagnets. Those magnets, Monroe believes, could be interacting in ways to solve a certain problem very quickly without quantum mechanics. "There's no evidence that what they're doing has anything to do with quantum mechanics," he says. If he's right, then D-Wave's machine may be far more narrow in its abilities than the company believes.
D-Wave's Geordie Rose acknowledges the criticism, but says he believes that D-Wave's machine ultimately will also prove faster than conventional computers at solving the problems facing companies like Google, NASA and aerospace giant Lockheed Martin (which has also purchased a machine).
"What we do is build computers," Rose says, "and if we can build the fastest computers the world has ever known, you can call them whatever you like, and I'll be happy."
LINDA WERTHEIMER, HOST:
Google and NASA have partnered to purchase a new kind of computer, one that uses quantum mechanics to solve problems that are too complex for regular computers.
NPR's Geoff Brumfiel takes a look at the next generation of computing technology.
GEOFF BRUMFIEL, BYLINE: This new quantum computer is literally a black box the size of a small room, or to be more precise, a black cube.
Geordie Rose is chief technology officer with D-Wave Systems, the Canadian company that made the machine.
GEORDIE ROSE: Inside that black cube is a machine called a dilution refrigerator which cools the brains of the computer down to just a fraction above absolute zero.
BRUMFIEL: At these extremely low temperatures, the rules of quantum mechanics take over. These rules are very different from those used in a normal computer. For example, a regular computer can only work with separate bits of information: ones and zeros. But in a quantum computer...
CHRISTOPHER MONROE: There's a certain intrinsic wiring between the bits that sort of comes for free. It's called quantum entanglement.
BRUMFIEL: Christopher Monroe is a physicist at the University of Maryland's Joint Quantum Institute.
MONROE: Quantum computers use, they exploit this resource called entanglement to do certain tasks that can be shown for certain problems to be exponentially faster than what could be done without a quantum computer.
BRUMFIEL: What might take decades can be done in hours. D-Wave claims its latest processor has 512 quantum bits. That's enough to tackle some really tough problems, says Geordie Rose. In particular, problems that require sifting through lots and lots of possible answers.
ROSE: The best answer or the highest or the lowest or the smallest or the meatiest, you know, no matter what. If it's got an iest at the end and you can write down a mathematical equation for what you mean about that, then you can attack it with one of our machines.
BRUMFIEL: And that's why Google and NASA are interested. They've partnered with an independent research association to start a quantum artificial intelligence lab centered around the D-Wave computer. Both organizations want to develop systems that can learn to spot patterns in massive, messy datasets.
ROSE: They want to continue to understand how to increase the intelligence of machines.
BRUMFIEL: But many scientists still have questions about how well the D-Wave computer really works. Until now, most quantum computing has been done on a small scale. And physicist Chris Monroe says that D-Wave's 512-bit chip may be too big to keep everything entangled.
MONROE: If you make the system bigger, in every platform I know of it gets harder, and in fact, the entanglement goes away faster.
BRUMFIEL: Too fast to do any calculations. D-Wave's computer is solving tough problems and for specific cases it can beat a conventional rival. But the company hasn't been able to convince Monroe that entanglement is doing the work.
MONROE: They've shown no evidence of entanglement, now that doesn't mean to say that what they're doing is not interesting.
BRUMFIEL: Monroe says this new chip is so unusual in its design that it might be working in a way that can sometimes beat other computers, even without entanglement. D-Wave's Geordie Rose says that's fine with him.
ROSE: Academic groups tend to want to focus more on the quantum part than the computing part, and that's fine. It's just not what we do. What we do is build computers, and if we can build the fastest computers the world has ever known, you can call them whatever you like and I'll be happy.
BRUMFIEL: Regardless of what D-Wave's machine is doing, quantum computing is not going away. The strange rules of quantum physics are just too tempting for technology companies to ignore.
Geoff Brumfiel, NPR News. Transcript provided by NPR, Copyright NPR.