Tracing uncertainty: Google harnesses quantum mechanics in a California lab

Tracing uncertainty: Google harnesses quantum mechanics in a California lab

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Goleta (United States) (AFP) – Outside, the warm September sun warms an idyllic coast as California enjoys another perfect day.

Inside, it’s minus 460 degrees Fahrenheit (-273 degrees Celsius) in some places, pockets of cold bristling 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 lab, where dozens of super-smart people work in an office outfitted with climbing walls and e-bikes to shape the next generation of computers – a generation that will look like nothing like this. that users currently have in their pockets or desks.

“It’s a new type of computer that uses quantum mechanics to do calculations and allows us… to solve problems that would otherwise be impossible,” says Erik Lucero, chief engineer at the campus near Santa Barbara.

“It’s not going to replace your cell phone, your desktop computer; it’s going to work alongside those things.”


Quantum mechanics is an area of ​​research that scientists believe could one day be used to help limit global warming, design urban traffic systems, or develop powerful new drugs.

The promises are so great that governments, tech giants and start-ups around the world are investing billions of dollars in them, employing some of the world’s greatest minds.

Schrödinger’s cat

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

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

The most famous illustration of a quantum superposition is Schrodinger’s cat – a hypothetical animal enclosed in a box with a vial of poison that may or may not break.


While the box is closed, the cat is both alive and dead. But once you interfere with the quantum state and open the box, the cat’s life or death question is resolved.

Quantum computers use this uncertainty to perform many seemingly contradictory calculations at the same time – much like being able to navigate all possible routes through a maze at once, instead of trying each in series until you find the right path.

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

As soon as something interferes with them – noise, mud, bad weather – the overlay crumbles and you end up with a random and probably nonsensical response.


The quantum computer that Google showed reporters looks like a steampunk wedding cake hanging upside down from a support structure.

Each layer of metallic, curved wires cools gradually, until the final stage, where the palm-sized processor is cooled to just 10 millikelvin, or about -460 degrees Fahrenheit (-273 degrees Celsius).

This temperature – just a shade above absolute zero, the lowest possible temperature in the universe – is vital to the superconductivity on which Google’s design is based.

Although the layer cake computer isn’t huge – about half a person tall – a decent amount of lab space is taken up by equipment to cool it – pipes hiss overhead with helium dilutions compressing and expanding, using the same process that keeps your fridge cold.


But… what does all this really do?

Well, says Daniel Lidar, an expert in quantum systems at the University of Southern California, this is a field that holds great promise when it matures, but is still in its infancy.

“We learned to crawl but we certainly haven’t learned to walk, jump or run yet,” he told AFP.


Key to its growth will be solving the problem of superpositional collapses – opening the chat box – to allow meaningful calculations.

As this error-correcting process improves, problems like optimizing city traffic, which is fiendishly difficult on a conventional computer because of the number of independent variables involved – the cars themselves – could be within reach, Lidar said.

“On a quantum computer (with error correction) you could solve this problem,” he said.

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

“Quantum mechanics is one of the best theories we have today for experimenting with nature. It’s a computer that speaks the language of nature.

“And if we want to go out and solve these really tough problems, to help save our planet, and things like climate change, rather than having a computer that can do exactly that, I would want that.”

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