Google quantum computer leaves old-school supercomputer in the dust - CNET

Google's Sycamore chip powers a quantum computer
Google

A Google quantum computer has far outpaced ordinary computing technology, an achievement called quantum supremacy that's an important milestone for a revolutionary way of processing data. Google disclosed the results in the journal Nature on Wednesday. It came after more than a decade of work at Google, including the use of its own quantum computing chip, called Sycamore.

"Our machine performed the target computation in 200 seconds, and from measurements in our experiment we determined that it would take the world's fastest supercomputer 10,000 years to produce a similar output," Google researchers said in a blog post about the work.

The achievement, which leaked into the limelight in September with a premature paper publication, doesn't mean the beginning of the end for classical computers, at least in the view of today's quantum computing experts. Quantum computers are expected to be good at some particular chores -- optimizing investment portfolios and developing new drugs at the molecular level, for example -- but not most of what we do today on computers.

Google's result does offer evidence, though, that quantum computers could break out of research labs and head toward mainstream computing.

Quantum computing researcher Scott Aaronson likened the step to landing on the moon in terms of momentousness. And Google Chief Executive Sundar Pichai called it a "big breakthrough" in a tweet Wednesday.

A vast industry is devoted to improving classical computers, but a small number of expensive labs at companies such as Google, Intel, Microsoft, Honeywell, Rigetti Computing and IBM are pursuing general-purpose quantum computers, too. They're finicky devices, running just a hair's breadth above absolute zero to minimize the likelihood they'll be perturbed. Don't expect to find quantum computers are not the kind of thing you can expect to find on your desk.

Google's speed test has applications to computing work like artificial intelligence, materials science and random number generation, the paper said. "

However, physicist Jim Preskill, who came up with the term quantum supremacy in 2012, dashed some cold water on that idea. Google's chosen test was good for showing quantum computing speed but "not otherwise a problem of much practical interest," Preskill said in October after the paper's premature release.

Quantum vs. classical computers

Nearly every digital device so far, from ENIAC in 1945 to Apple's iPhone 11 in 2019, is called a classical computer. Their electronics rely on logic circuits to do things like add two numbers and memory cells to store the results.

Google quantum computer looks nothing like a conventional machine. When running, all this complexity is hidden away and refrigerated to near absolute zero.
Google

Quantum computers are entirely different, reliant instead on the mind-bending rules of physics that govern ultrasmall objects like atoms.

Where classical computers store and process data as individual bits, each a 1 or a 0, quantum computers use a different foundation called a qubit. Each qubit can store a combination of different states of 1 and 0 at the same time through a phenomenon called superposition. Told you it was weird.

Not only that, but multiple qubits can be ganged together through another quantum phenomenon called entanglement. That lets a quantum computer explore a vast number of possible solutions to a problem at the same time.

Exponential speedups

In principle, a quantum computer's performance grows exponentially: add one more qubit, and the number of solutions you can examine in one fell swoop doubles. For that reason, quantum computing engineers are working to increase the number of qubits in their machines.

"We expect that their computational power will continue to grow at a double-exponential rate," the Google researchers said in their paper. That's even faster than the single exponential improvement charted for classical computer chips by Moore's Law.

Google's machine had 54 qubits, though one wasn't working right, so only 53 were available. That happens to match the number in IBM's most powerful quantum computer.

But qubit count isn't everything. Unavoidable instabilities cause qubits to lose their data. To counteract that problem, researchers are also working on error-correction techniques to let a calculation sidestep those problems.

IBM challenges Google's quantum results

IBM is a major quantum computing fan, but it questioned Google's prematurely released results in a blog post Monday.

"We argue that an ideal simulation of the same task can be performed on a classical system in 2.5 days and with far greater fidelity," IBM researchers wrote. They suggested different algorithms and a different classical computer design in a preprint paper of their own.

Google said it welcomes improvements to quantum computer simulation techniques but said its overall result is "prohibitively hard for even the world's fastest supercomputer, with more double exponential growth to come. We've already peeled away from classical computers, onto a totally different trajectory."

Intel didn't offer an opinion on Google's results, but did say quantum supremacy is "a strategic benchmark."

"We are committed to moving quantum from the lab to commercialization," said Jim Clarke, Intel Labs' director of quantum hardware, in a statement.

Cracking your encrypted communications? Not yet

One quantum computing ability, mathematically proved with an idea called Shor's algorithm, is cracking some of today's encryption technology.

However, that will require vastly larger quantum computers and new technology breakthroughs to deal with error correction.

"Realizing the full promise of quantum computing (using Shor's algorithm for factoring, for example) still requires technical leaps," the researchers said in their paper.

And at the same time, the US government and others are working on "post-quantum" cryptography methods to withstand quantum computing cracking abilities.

So for now at least, quantum computing, while radically different, isn't blowing up the tech industry.

First published Oct. 23, 2:15 a.m. PT.

Update, 3:09 a.m. PT: Adds more detail and comment from Google CEO.

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