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Supercomputing Science

A Quantum Error Correction Breakthrough? (harvard.edu) 29

The dream of quantum computers has been hampered by the challenge of error correction, writes the Harvard Gazette, since qubits "are inherently susceptible to slipping out of their quantum states and losing their encoded information."

But in a newly-published paper, a research team "combined various methods to create complex circuits with dozens of error correction layers" that "suppresses errors below a critical threshold — the point where adding qubits further reduces errors rather than increasing them." "For the first time, we combined all essential elements for a scalable, error-corrected quantum computation in an integrated architecture," said Mikhail Lukin, co-director of the Quantum Science and Engineering Initiative, Joshua and Beth Friedman University Professor, and senior author of the new paper. "These experiments — by several measures the most advanced that have been done on any quantum platform to date — create the scientific foundation for practical large-scale quantum computation..."

"There are still a lot of technical challenges remaining to get to very large-scale computer with millions of qubits, but this is the first time we have an architecture that is conceptually scalable," said lead author Dolev Bluvstein, Ph.D. '25, who did the research during his graduate studies at Harvard and is now an assistant professor at Caltech. "It's going to take a lot of effort and technical development, but it's becoming clear that we can build fault-tolerant quantum computers...."

Hartmut Neven, vice president of engineering at the Google Quantum AI team, said the new paper came amid an "incredibly exciting" race between qubit platforms. "This work represents a significant advance toward our shared goal of building a large-scale, useful quantum computer," he said... With recent advances, Lukin believes the core elements for building quantum computers are falling into place. "This big dream that many of us had for several decades, for the first time, is really in direct sight," he said.

"In theory, a system of 300 quantum bits can store more information than the number of particles in the known universe..." the article points out.

"The new paper represents an important advance in a three-decade pursuit of quantum error correction."

Thanks to long-time Slashdot reader schwit1 for sharing the article.

A Quantum Error Correction Breakthrough?

Comments Filter:
  • by ffkom ( 3519199 ) on Saturday November 15, 2025 @07:43PM (#65798081)

    "In theory, a system of 300 quantum bits can store more information than the number of particles in the known universe..." the article points out.

    Good to have this in the abstract, so I can save the time reading that article, which so clearly is delusional.

    • Yeah howâ(TM)s anyone storing more information than the universe and doing it in the universe
    • ... all those investments in data centers.

    • Re:Fairy tales (Score:4, Insightful)

      by ClickOnThis ( 137803 ) on Saturday November 15, 2025 @09:07PM (#65798175) Journal

      "In theory, a system of 300 quantum bits can store more information than the number of particles in the known universe..." the article points out.

      Good to have this in the abstract, so I can save the time reading that article, which so clearly is delusional.

      I read that and decided it wasn't worth reading any further, not because it's delusional, but because it's meaningless.

      How much information is contained in "the number of particles in the known universe?" Thant's a number between 10^80 and 10^82, or about 2^265 to 2^273. That number can be stored easily in 300 ordinary bits.

      Or maybe they mean something else?

      • by burtosis ( 1124179 ) on Saturday November 15, 2025 @09:09PM (#65798179)

        Or maybe they mean something else?

        What they were trying to say is your user name.

      • Wait, I think I have my own answer. Maybe they were referring to the number of states 300 qbits could represent simultaneously. Yes, that would be 2^300, well over the number of particles in the universe.

      • by gweihir ( 88907 )

        Or maybe they mean something else?

        They just mean "Ignore the facts, please believe this thing is powerful!"

      • Writing down an arbitrary state of a 300 qubit system would take ~2^307 bits depending on your level of floating point precision. It is dumb to say it stores information though, because even theoretically you can't get that information back out without making considerably more than 2^300 measurements.
    • Clearly you haven't studied the fundamentals of quantum computing which are marketing hype, hooey, pandering to venture capital investors or being researchers planning on all of the above.

    • by cboles ( 2626815 )
      It's a terrible phrasing, but 300 qubits (with binary states, let's just call it 300-bits) CAN store more information than the (number of particles in the known universe). The number of atomic particles in the universe is roughly 10^80, maybe 10^90 if you want to count all the longer-lived subatomic particles including photon and neutrinos. 10^90 is less than 2^300. It can store more information than that *number*. Can it store more than the particles? - of course not.
    • by gweihir ( 88907 )

      Delusions is what keeps the QC hype alive. Substance and understanding has left the building a long, long time ago. See also the LLM hype, the crapto hype and several other entirely demented hypes.

      Nice explanation from an actual expert: https://www.cs.auckland.ac.nz/... [auckland.ac.nz]

  • If I had a penny every time I heard this in a quantum computing paperâ¦
    • by kmoser ( 1469707 )
      2026 will surely be the year of quantum computing, Linux on the desktop, and full self driving cars!
  • I haven't been paying close attention, thus my first question: did they manage to factor an arbitrary number larger than 21?

    • by gweihir ( 88907 )

      Was it 21? I thought 35. I may be wrong though.

      No, they have not. Some people did a larger, fake on a Quantum Annealer (which is not a QC and the computation is unable to scale), but for a real QC is 21 or 35 and that is with a custom algo (i.e. essentially a fake), not Shor's. After 50 years of research. Calling these "computing" is ludicrous. These are Physics experiments, not more.

  • Whoever came up with the line “... a system of 300 quantum bits can store more information than the number of particles in the known universe” should probably have their nerd license suspended. Yes, 300 qubits form an insanely large state space, but that doesn’t mean they store that much information. Calling it “storage” is very misleading terminology. By that logic, throwing 300 coins into the air stores a massive amount of information. :)
    • by gweihir ( 88907 )

      It is all lies by misdirection to simulate an imminent usefulness that is not there and not even on the distant horizon. This is just one more of these lies.

    • The coins *can* store that much information but you have to keep your eyes closed, and it collapses to 300 bits when you open them. But coins can't do computation while they're in the air and that's why they're pretty useless as quantum computers.
  • Quantum noise (Score:4, Insightful)

    by WaffleMonster ( 969671 ) on Saturday November 15, 2025 @09:00PM (#65798163)

    Any article talking about qubit counts should reference the computers capabilities in terms of logical qubits.

    Any article talking about error correction should provide a scaling law for the required fanout of correction circuitry as a function of logical qubit count.

    Any article failing to do either of these things is a waste of time.

    • In modern error correction algorithms like the surface code and stabilizers, logical qubits aren't strictly defined. It's not like Shor's algorithm (no his other algorithm, the first quantum error correction) where you treat 9 physical qubits as a single logical qubit. The boundaries between "logical" qubits overlap and scale dynamically. As for connection circuitry, pretty much all qubits can be directly entangled to nearest neighbors in grids, and that hasn't changed nor is it likely to change in a while.
  • by gweihir ( 88907 )

    They are just trying to make the dead horse look alive. Somewhat alive. There have been tons of similar lies for the last 50 years, this is just one more.

    The whole thing is nonsense at current tech levels. The actual factorization record for QCs is 35 (that is 6 bit), and not with Shor's algorithm, but a custom one that can only factor 35, because it needs less resources and a shorter computation. That is not even remotely on the level of a slow 4 bit CPU from 50 years ago. After basically 50 years of resea

    • I know! When will people learn that you shouldn't try to do things that are hard?
      • by gweihir ( 88907 )

        What stupid-ass summary is that? What you should not do is predict a technology will be useful "soon" when all the evidence says otherwise. For QCs, if they scale linearly (they likely do much worse), they will be a problem for current encryption around the year 4000 or so. There is nothing wrong with running Physics experiments. But you need to see them as what they are.

    • They are just trying to make the dead horse look alive. Somewhat alive.

      A Schrodinger's Horse? Since it's a quantum stuff it'd be fitting.

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