4 ms·

>the more qubits we use in Willow, the more we reduce errors, and the more quantum the system becomes That's an EXTRAORDINARY claim and one that contradicts th

>the more qubits we use in Willow, the more we reduce errors, and the more quantum the system becomes That's an EXTRAORDINARY claim and one that contradicts the experience of pretty much all other research and development in quantum error correction over the course of the history of quantum computing.

wasabi991011 2y ago
It's really not so extraordinary, exponential reduction in logical errors when the physical error rate is below a threshold (for certain types of error correcting codes_ is well accepted an both theoretical and computational grounds. For a rough but well-sourced overview, see Wikipedia: https://en.wikipedia.org/wiki/Threshold_theorem https://en.wikipedia.org/wiki/Threshold_theorem For a review paper on surface codes, see A. G. Fowler, M. Mariantoni, J. M. Martinis, and A. N. Cleland, “Surface codes: Towards practical large-scale quantum computation,” Phys. Rev. A, vol. 86, no. 3, p. 032324, Sep. 2012, doi: 10.1103/PhysRevA.86.032324.
- DebtDeflation 2y ago
  Does this not assume uncorrelated errors?
  - wasabi991011 2y ago
    It does. It's up to engineering to make errors uncorrelated. The google paper being referenced actually makes an "error budget" to see what the main sources of errors are, and also run tests to find sources of correlated errors. The claim about this is that correlated errors will lead to an "error floor", a certain size of error correction past which exponential reduction in errors no longer applies, due to a certain frequency of correlated errors. See figure 3a of the arxiv version of the paper: https://arxiv.org/abs/2408.13687 https://arxiv.org/abs/2408.13687
qnleigh 2y ago
I wouldn't call it extraordinary, as this has been expected since the first quantum error correcting codes were worked out theoretically. But it is a strong claim, backed up with comparably strong evidence. Figure 1d of the paper shows exactly this https://arxiv.org/html/2408.13687v1 https://arxiv.org/html/2408.13687v1, and unlike many other comparable works, there are no hat tricks like post-selection to boost the numbers.
deepburner 2y ago
it... doesn't? threshold theorems are well known.
da-bacon 2y ago
>That's an EXTRAORDINARY claim and one that contradicts the experience of pretty much all other research and development in quantum error correction over the course of the history of quantum computing. Not sure why you would say that? This sort of exponential suppression of errors is exactly how quantum error correction works and why we think quantum computing is viable. Source: have worked on quantum error correction for a couple of decades. Disclosure: I work on the team that did this experiment. More reading: lecture notes from back in the day explaining this exponential suppression https://courses.cs.washington.edu/courses/cse599d/06wi/lecturenotes19.pdf https://courses.cs.washington.edu/courses/cse599d/06wi/lectu...
pjs_ 2y ago
It's a categorically new experimental regime but it's exactly what was supposed to happen. I think it's an awesome result.

wasabi991011 2y ago

It's really not so extraordinary, exponential reduction in logical errors when the physical error rate is below a threshold (for certain types of error correcting codes_ is well accepted an both theoretical and computational grounds. For a rough but well-sourced overview, see Wikipedia: https://en.wikipedia.org/wiki/Threshold_theorem https://en.wikipedia.org/wiki/Threshold_theorem For a review paper on surface codes, see A. G. Fowler, M. Mariantoni, J. M. Martinis, and A. N. Cleland, “Surface codes: Towards practical large-scale quantum computation,” Phys. Rev. A, vol. 86, no. 3, p. 032324, Sep. 2012, doi: 10.1103/PhysRevA.86.032324.

DebtDeflation 2y ago
Does this not assume uncorrelated errors?
- wasabi991011 2y ago
  It does. It's up to engineering to make errors uncorrelated. The google paper being referenced actually makes an "error budget" to see what the main sources of errors are, and also run tests to find sources of correlated errors. The claim about this is that correlated errors will lead to an "error floor", a certain size of error correction past which exponential reduction in errors no longer applies, due to a certain frequency of correlated errors. See figure 3a of the arxiv version of the paper: https://arxiv.org/abs/2408.13687 https://arxiv.org/abs/2408.13687

qnleigh 2y ago

I wouldn't call it extraordinary, as this has been expected since the first quantum error correcting codes were worked out theoretically. But it is a strong claim, backed up with comparably strong evidence. Figure 1d of the paper shows exactly this https://arxiv.org/html/2408.13687v1 https://arxiv.org/html/2408.13687v1, and unlike many other comparable works, there are no hat tricks like post-selection to boost the numbers.

deepburner 2y ago

it... doesn't? threshold theorems are well known.

da-bacon 2y ago

>That's an EXTRAORDINARY claim and one that contradicts the experience of pretty much all other research and development in quantum error correction over the course of the history of quantum computing. Not sure why you would say that? This sort of exponential suppression of errors is exactly how quantum error correction works and why we think quantum computing is viable. Source: have worked on quantum error correction for a couple of decades. Disclosure: I work on the team that did this experiment. More reading: lecture notes from back in the day explaining this exponential suppression https://courses.cs.washington.edu/courses/cse599d/06wi/lecturenotes19.pdf https://courses.cs.washington.edu/courses/cse599d/06wi/lectu...

pjs_ 2y ago

It's a categorically new experimental regime but it's exactly what was supposed to happen. I think it's an awesome result.