[HN Gopher] Qubit Transistors Reach Error Correction Benchmark
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Qubit Transistors Reach Error Correction Benchmark
Author : rbanffy
Score : 56 points
Date : 2024-09-12 12:07 UTC (10 hours ago)
(HTM) web link (spectrum.ieee.org)
(TXT) w3m dump (spectrum.ieee.org)
| pechay wrote:
| University of New South Whales!
| xnx wrote:
| *Wales
| karlgkk wrote:
| Didn't read the article, did you?
| brutal_chaos_ wrote:
| I think the article has been corrected. I read it after
| seeing this comment and couldn't find whales while reading
| nor with ctrl+f
| deathanatos wrote:
| It was: http://web.archive.org/web/20240911190011/https:/
| /spectrum.i...
| aidenn0 wrote:
| Misspelling aside, Mitchell and Webb have ruined me; any time I
| hear the name of that state, I think of[1]
|
| 1: https://www.youtube.com/watch?v=WxKnFckhzUs
| m3kw9 wrote:
| Just like fashion, even scientific advances can go from advanced
| looking back to retro
| AlanYx wrote:
| The linked article says that they've achieved "the baseline
| necessary to perform error correction". With the stated error
| rate, roughly how many physical qubits would be required to
| produce one error-corrected logical qubit?
| crdrost wrote:
| So it can be as low as 3 if you're only concerned with some of
| the noise, but if you're trying to correct both for bit flips
| (0 exchanged for 1 and vice versa) and phase drift (0 + 1 being
| exchanged for 0 - 1 and vice versa) then you need at least 5
| physical qubits to create one logical qubit, see [wiki] for
| details.
|
| [wiki]: https://en.wikipedia.org/wiki/Five-
| qubit_error_correcting_co...
| Strilanc wrote:
| The threshold is where you transition from needing infinite
| qubits to make an error corrected logical qubit, to needing a
| mere finite number. So... somewhere between 1 and infinity
| (exclusive).
|
| Actually, because "in theory there's no difference between
| theory and practice but in practice there is", the number is
| _probably_ still infinity. Like, if you look at figure 4 of
| their paper [0], you can see one device of the three is well
| above threshold at 1.5% error. They need sufficient quality
| more consistently before a large system built out of the pieces
| they are benchmarking would be below threshold.
|
| [1]:
| https://www.nature.com/articles/s41567-024-02614-w/figures/4
| jgeada wrote:
| This is interesting, but what isn't mentioned is how long these
| devices can hold coherence (see
| https://en.wikipedia.org/wiki/Charge_qubit and
| https://en.wikipedia.org/wiki/Quantum_decoherence)
|
| All existing QC approaches have two fundamental limitations:
| error rate and coherence time. You can decrease error rate
| through error correction, but that comes at the cost of adding
| gates and/or storage to replicate the QC state, but that causes a
| decrease in coherence time. I have not seen even a theoretical
| framework allowing both to be increased simultaneously.
| amirhirsch wrote:
| I will bet $2048 that a quantum computer will not factor
| RSA2048 by 2048.
| kurthr wrote:
| I would not bet against you, but I suspect any advances will
| be made very quickly and that could happen any time in the
| next 25 years.
|
| Even at 0.001% risk is far too much to take. I'd certainly
| make the $0.02 bet for those odds.
| almostgotcaught wrote:
| > I would not bet against you
|
| So you don't think it'll happen by 2048
|
| > but I suspect any advances will be made very quickly and
| that could happen any time in the next 25 years.
|
| Um 2024 + 25 = 2049
| Strilanc wrote:
| > _I have not seen even a theoretical framework allowing both
| to be increased simultaneously._
|
| The threshold theorem [1], showing this can be done in
| principle, was proven more than a decade ago.
|
| But you don't have to believe the theory anymore, there's
| experiments now! Last month the google quantum computing team
| published an experiment [2] showing memory error rates
| (including decoherence) getting twice as good as a surface code
| was grown from distance 3 to distance 5, and twice as good
| again going from distance 5 to distance 7. The logical qubit's
| coherence time was longer than the coherence times of the
| physical qubits it was built out of.
|
| [1]: https://en.wikipedia.org/wiki/Threshold_theorem
|
| [2]: https://arxiv.org/abs/2408.13687
| dvh wrote:
| Ok let's say I have two entangled electrons. How do I get one to
| first transistor and second to second transistor?
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