Physicists Move Closer To Defeating Errors In Quantum Computation

sciencehabit shares a report from Science Magazine: Physicists at Google have taken an important step toward protecting delicate information in their nascent quantum computer from errors that can obliterate it. The researchers can't yet compensate for all types of errors -- a necessary step toward building a full-fledged quantum computer -- but others say they're poised to achieve that goal. Working with chains of up to 11 data qubits, Google researchers have now been able to preserve a logical qubit for a time that increases exponentially with the number of physical qubits, they report today in Nature. By spreading a single qubit's state over up to 11 data qubits, they reduced the chances of an error after 50 microseconds from 40% to 0.2%. Other groups have demonstrated similar error corrections schemes, but the new work is the first to demonstrate the exponential suppression of errors, says Julian Kelly, a physicist at Google and senior author on the paper. Such exponential suppression suggests developers may eventually be able to maintain a logical qubit indefinitely by spreading it over about 1000 physical qubits.

Two different ways of handling errors

[JoshuaZ]

When classical computers were very young, there were two major ways of handling errors. One was error correction and error detecting aspects in the processes themselves. (So things like parity checks on operations.) The other was making computing so reliable that errors occurred very rarely. As we developed better machines, it turned out that the second one if one could get it good enough made the first substantially less relevant. The same thing is happening with quantum computers; either make qubits more robust, or make error correction better. Although it isn't obvious from the summary, it appears from actually clicking through and reading the linked article https://www.nature.com/articles/s41586-021-03588-y [nature.com] that this is work on the error correction end. Very likely actual quantum computers in order to be practical will need improvements in both aspects than what we have now: both lower error rates, and better error correction.

Re:

[Viol8]

Isn't it the nature of quantum computing that errors are unavoidable due to the random wave function collapse so perhaps error correction is the only way forward in this case?

Re:

[ceoyoyo]

Yes, but there's a lot you can do to improve the situation by isolating your qubits from the environment. Most QC people think there will be an era of noisy machines requiring lots of error correction, followed by improvements in the noise performance, much the way the OP said.

You're never going to get qubits that are as stable as transistors in a classical computer, but it's pretty likely we can do better than the current state of the art.

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[Falconhell]

I thought about starting a business called Quantum Mechanical Repairs- No job too small! :)

So ...

[fahrbot-bot]

By spreading a single qubit's state over up to 11 data qubits, they reduced the chances of an error after 50 microseconds from 40% to 0.2%.

Good enough to calculate hiking routes [slashdot.org]? :-)

Re: So ...

[anonymouscoward52236]

Yes. Quantum computers can be used to find optimal solutions to the traveling salesman problem. Also, of you didn't know, you can rent a multi-million dollar quantum computer by the hour with AWS Braket. https://github.com/aws/amazon-... [github.com]

Heisenberg Compensator anyone?

[burni2]

https://www.youtube.com/watch?... [youtube.com]

Error correction needs more qbits

[mrclevesque]

From the summary:

"By spreading a single qubit's state over up to 11 data qubits, they reduced the chances of an error after 50 microseconds from 40% to 0.2%. ... Such exponential suppression suggests developers may eventually be able to maintain a logical qubit indefinitely by spreading it over about 1000 physical qubits."

A small step on the way.

"To encode the data in a single qubit with sufficient fidelity, they may need to master 1000 of them."

https://www.sciencemag.org/new... [sciencemag.org]

Sooo

[gweihir]

1000 physical qbits for one logical one. Given that _nobody_ is able to handle 1000 entangled qbits and that it is unclear whether that is even within what can be done, they currently have zero stable logical qbits and no idea whether they can ever get even one. And they talk about practical applications? What incredible fools are at work in that community?

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[localroger]

I believe the technical term for the current state of the art is "moonshine."

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[OneHundredAndTen]

I thought it was 'mostly BS'.

Re: Sooo

[Jeremi]

https://www.oxfordreference.co... [slashdot.org]â>Fools and bairns should never see halfâdone work

They may mistakenly judge the quality of the finished article from its awkwardness while it is being produced.

Re:

[ceoyoyo]

You don't need to keep them stable indefinitely.

QC is still a blue sky project. Practical, fully general implementations might well be impossible, but they also might not be.

"Incredible fools" is quite a bit of hubris on your part.

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[gweihir]

You don't need to keep them stable indefinitely.

QC is still a blue sky project. Practical, fully general implementations might well be impossible, but they also might not be.

"Incredible fools" is quite a bit of hubris on your part.

"Incredible fools" is having watched them promise things but never deliver for something like 30 years now. I could also have called them "honor-less scum". In fact, maybe I should have done that.

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[ceoyoyo]

30 years hey? Lol, yeah, that Feynman clown was certainly a fool.

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[Tough Love]

Research in quantum computing has driven advances in photonics and other fields that are already out of the lab and into the engineering realm.

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[Tough Love]

Already well below the error rate of politicians.

Enterprise Computer

[CRB9000]

Spock: Computer, what is the origin of the spacecraft? Computer: The spacecraft originates from the Andromeda galaxy...or, not.