Google harnesses quantum mechanics

OUTSIDE, balmy September sunshine warms an idyllic coast, as California basks in yet another perfect day.

Inside, it’s -273°C in some spots, pockets of cold that bristle with the impossible physics of quantum mechanics – a science in which things can simultaneously exist, not exist and also be something in between.

This is Google’s Quantum AI laboratory, where dozens of super-smart people labour in an office kitted out with climbing walls and electric bikes to shape the next generation of computers – a generation that will be unlike anything users have in their pockets or offices.

“It is a new type of computer that uses quantum mechanics to do computations and allows us to solve problems that would otherwise be impossible,” explains Erik Lucero, lead engineer at the campus near Santa Barbara.

Old fashioned computing is built on the idea of binary certainty: tens of thousands of “bits” of data that are each definitely either “on” or “off,” represented by either a one or a zero.

Quantum computing uses uncertainty: its “qubits” can exist in a state of both one-ness and zero-ness in what is called a superposition.

Quantum computers use this uncertainty to perform lots of seemingly contradictory calculations at the same time – a bit like being able to go down every possible route in a maze all at once, instead of trying each one in series until you find the right path.

The difficulty for quantum computer designers is getting these qubits to maintain their superposition long enough to make a calculation.

As soon as something interferes with them the superposition collapses, and you’re left with a random and likely nonsensical answer.

In Google’s quantum computer each layer of metal and curved wires gets progressively colder, down to the final stage, where the palm-sized processor is cooled to just 10 millikelvin, or about -273°C.

That temperature – only a shade above absolute zero, the lowest temperature possible in the universe – is vital for the superconductivity Google’s design relies on.

While the computer is not huge – about half a person high – a decent amount of lab space is taken up with the equipment to cool it – pipes whoosh overhead with helium dilutions compressing and expanding, using the same process that keeps your refrigerator cold.

Daniel Lidar, an expert in quantum systems at the University of Southern California, says quantum computing is a field that promises much when it matures, but which is still a toddler.

“We’ve learned how to crawl but we’ve certainly not yet learned how to how to walk or jump or run.”

The key to its growth will be solving the problem of the superpositional collapses to allow for meaningful calculations.

As this process of error correction improves, problems such as city traffic optimisation, which is fiendishly hard on a classical computer because of the number of independent variables involved – the cars themselves – could come within reach, said Lidar.

“On (an error-corrected) quantum computer, you could solve that problem,” he said.

For Lucero and his colleagues, these future possibilities are worth the brain ache.

“Quantum mechanics is one of the best theories that we have today to experience nature. This is a computer that speaks the language of nature.

“And if we want to go out and figure out these really challenging problems, to help save our planet, and things like climate change, than having a computer that can do exactly that, I’d want that.” |