The article is called “The Revolutionary Quantum Computer That May Not Be Quantum at All” and it is another review of the work being done at D-Wave who claim on their website, “The Quantum Computing Era Has Begun.”
The Revolutionary Quantum Computer That May Not Be Quantum at All
Google owns a lot of computers—perhaps a million servers stitched together into the fastest, most powerful artificial intelligence on the planet. But last August, Google teamed up with NASA to acquire what may be the search giant’s most powerful piece of hardware yet. It’s certainly the strangest.
Located at NASA Ames Research Center in Mountain View, California, a couple of miles from the Googleplex, the machine is literally a black box, 10 feet high. It’s mostly a freezer, and it contains a single, remarkable computer chip—based not on the usual silicon but on tiny loops of niobium wire, cooled to a temperature 150 times colder than deep space. The name of the box, and also the company that built it, is written in big, science-fiction-y letters on one side: D-WAVE. Executives from the company that built it say that the black box is the world’s first practical quantum computer, a device that uses radical new physics to crunch numbers faster than any comparable machine on earth. If they’re right, it’s a profound breakthrough. The question is: Are they?
Hartmut Neven, a computer scientist at Google, persuaded his bosses to go in with NASA on the D-Wave. His lab is now partly dedicated to pounding on the machine, throwing problems at it to see what it can do. An animated, academic-tongued German, Neven founded one of the first successful image-recognition firms; Google bought it in 2006 to do computer-vision work for projects ranging from Picasa to Google Glass. He works on a category of computational problems called optimization—finding the solution to mathematical conundrums with lots of constraints, like the best path among many possible routes to a destination, the right place to drill for oil, and efficient moves for a manufacturing robot. Optimization is a key part of Google’s seemingly magical facility with data, and Neven says the techniques the company uses are starting to peak. “They’re about as fast as they’ll ever be,” he says.
That leaves Google—and all of computer science, really—just two choices: Build ever bigger, more power-hungry silicon-based computers. Or find a new way out, a radical new approach to computation that can do in an instant what all those other million traditional machines, working together, could never pull off, even if they worked for years.
That, Neven hopes, is a quantum computer. A typical laptop and the hangars full of servers that power Google—what quantum scientists charmingly call “classical machines”—do math with “bits” that flip between 1 and 0, representing a single number in a calculation. But quantum computers use quantum bits, qubits, which can exist as 1s and 0s at the same time. They can operate as many numbers simultaneously. It’s a mind-bending, late-night-in-the-dorm-room concept that lets a quantum computer calculate at ridiculously fast speeds.
Unless it’s not a quantum computer at all. Quantum computing is so new and so weird that no one is entirely sure whether the D-Wave is a quantum computer or just a very quirky classical one. Not even the people who build it know exactly how it works and what it can do. That’s what Neven is trying to figure out, sitting in his lab, week in, week out, patiently learning to talk to the D-Wave. If he can figure out the puzzle—what this box can do that nothing else can, and how—then boom. “It’s what we call ‘quantum supremacy,’” he says. “Essentially, something that cannot be matched anymore by classical machines.” It would be, in short, a new computer age.
A former wrestler short-listed for Canada’s Olympic team, D-Wave founder Geordie Rose is barrel-chested and possessed of arms that look ready to pin skeptics to the ground. When I meet him at D-Wave’s headquarters in Burnaby, British Columbia, he wears a persistent, slight frown beneath bushy eyebrows. “We want to be the kind of company that Intel, Microsoft, Google are,” Rose says. “The big flagship $100 billion enterprises that spawn entirely new types of technology and ecosystems. And I think we’re close. What we’re trying to do is build the most kick-ass computers that have ever existed in the history of the world.”
The office is a bustle of activity; in the back rooms technicians peer into microscopes, looking for imperfections in the latest batch of quantum chips to come out of their fab lab. A pair of shoulder-high helium tanks stand next to three massive black metal cases, where more techs attempt to weave together their spilt guts of wires. Jeremy Hilton, D-Wave’s vice president of processor development, gestures to one of the cases. “They look nice, but appropriately for a startup, they’re all just inexpensive custom components. We buy that stuff and snap it together.” The really expensive work was figuring out how to build a quantum computer in the first place.
Like a lot of exciting ideas in physics, this one originates with Richard Feynman. In the 1980s, he suggested that quantum computing would allow for some radical new math. Up here in the macroscale universe, to our macroscale brains, matter looks pretty stable. But that’s because we can’t perceive the subatomic, quantum scale. Way down there, matter is much stranger. Photons—electromagnetic energy such as light and x-rays—can act like waves or like particles, depending on how you look at them, for example. Or, even more weirdly, if you link the quantum properties of two subatomic particles, changing one changes the other in the exact same way. It’s called entanglement, and it works even if they’re miles apart, via an unknown mechanism that seems to move faster than the speed of light.
Knowing all this, Feynman suggested that if you could control the properties of subatomic particles, you could hold them in a state of superposition—being more than one thing at once. This would, he argued, allow for new forms of computation. In a classical computer, bits are actually electrical charge—on or off, 1 or 0. In a quantum computer, they could be both at the same time.
It was just a thought experiment until 1994, when mathematician Peter Shor hit upon a killer app: a quantum algorithm that could find the prime factors of massive numbers. Cryptography, the science of making and breaking codes, relies on a quirk of math, which is that if you multiply two large prime numbers together, it’s devilishly hard to break the answer back down into its constituent parts. You need huge amounts of processing power and lots of time. But if you had a quantum computer and Shor’s algorithm, you could cheat that math—and destroy all existing cryptography. “Suddenly,” says John Smolin, a quantum computer researcher at IBM, “everybody was into it.”
That includes Geordie Rose. A child of two academics, he grew up in the backwoods of Ontario and became fascinated by physics and artificial intelligence. While pursuing his doctorate at the University of British Columbia in 1999, he readExplorations in Quantum Computing, one of the first books to theorize how a quantum computer might work, written by NASA scientist—and former research assistant to Stephen Hawking—Colin Williams. (Williams now works at D-Wave.)
Reading the book, Rose had two epiphanies. First, he wasn’t going to make it in academia. “I never was able to find a place in science,” he says. But he felt he had the bullheaded tenacity, honed by years of wrestling, to be an entrepreneur. “I was good at putting together things that were really ambitious, without thinking they were impossible.” At a time when lots of smart people argued that quantum computers could never work, he fell in love with the idea of not only making one but selling it.
With about $100,000 in seed funding from an entrepreneurship professor, Rose and a group of university colleagues founded D-Wave. They aimed at an incubator model, setting out to find and invest in whoever was on track to make a practical, working device. The problem: Nobody was close.
At the time, most scientists were pursuing a version of quantum computing called the gate model. In this architecture, you trap individual ions or photons to use as qubits and chain them together in logic gates like the ones in regular computer circuits—the ands, ors, nots, and so on that assemble into how a computer thinks. The difference, of course, is that the qubits could interact in much more complex ways, thanks to superposition, entanglement, and interference.
But qubits really don’t like to stay in a state of superposition, what’s called coherence. A single molecule of air can knock a qubit out of coherence. The simple act of observing the quantum world collapses all of its every-number-at-once quantumness into stochastic, humdrum, nonquantum reality. So you have to shield qubits—from everything. Heat or other “noise,” in physics terms, screws up a quantum computer, rendering it useless.
You’re left with a gorgeous paradox: Even if you successfully run a calculation, you can’t easily find that out, because looking at it collapses your superpositioned quantum calculation to a single state, picked at random from all possible superpositions and thus likely totally wrong. You ask the computer for the answer and get garbage.
Lashed to these unforgiving physics, scientists had built systems with only two or three qubits at best. They were wickedly fast but too underpowered to solve any but the most prosaic, lab-scale problems. But Rose didn’t want just two or three qubits. He wanted 1,000. And he wanted a device he could sell, within 10 years. He needed a way to make qubits that weren’t so fragile.
“WHAT WE’RE TRYING TO DO IS BUILD THE MOST KICK-ASS COMPUTERS THAT HAVE EVER EXISTED IN THE HISTORY OF THE WORLD.”
In 2003, he found one. Rose met Eric Ladizinsky, a tall, sporty scientist at NASA’s Jet Propulsion Lab who was an expert in superconducting quantum interference devices, or Squids. When Ladizinsky supercooled teensy loops of niobium metal to near absolute zero, magnetic fields ran around the loops in two opposite directions at once. To a physicist, electricity and magnetism are the same thing, so Ladizinsky realized he was seeing superpositioning of electrons. He also suspected these loops could become entangled, and that the charges could quantum-tunnel through the chip from one loop to another. In other words, he could use the niobium loops as qubits. (The field running in one direction would be a 1; the opposing field would be a 0.) The best part: The loops themselves were relatively big, a fraction of a millimeter. A regular microchip fab lab could build them.
The two men thought about using the niobium loops to make a gate-model computer, but they worried the gate model would be too susceptible to noise and timing errors. They had an alternative, though—an architecture that seemed easier to build. Called adiabatic annealing, it could perform only one specific computational trick: solving those rule-laden optimization problems. It wouldn’t be a general-purpose computer, but optimization is enormously valuable. Anyone who uses machine learning—Google, Wall Street, medicine—does it all the time. It’s how you train an artificial intelligence to recognize patterns. It’s familiar. It’s hard. And, Rose realized, it would have an immediate market value if they could do it faster.
In a traditional computer, annealing works like this: You mathematically translate your problem into a landscape of peaks and valleys. The goal is to try to find the lowest valley, which represents the optimized state of the system. In this metaphor, the computer rolls a rock around the problem-scape until it settles into the lowest-possible valley, and that’s your answer. But a conventional computer often gets stuck in a valley that isn’t really lowest at all. The algorithm can’t see over the edge of the nearest mountain to know if there’s an even lower vale. A quantum annealer, Rose and Ladizinsky realized, could perform tricks that avoid this limitation. They could take a chip full of qubits and tune each one to a higher or lower energy state, turning the chip into a representation of the rocky landscape. But thanks to superposition and entanglement between the qubits, the chip could computationally tunnel through the landscape. It would be far less likely to get stuck in a valley that wasn’t the lowest, and it would find an answer far more quickly.
INSIDE THE BLACK BOX