Surface codes: Towards practical large-scale quantum computation · HackerPapers discussions

Surface codes: Towards practical large-scale quantum computation — mentioned by Strilanc

Wed, 01 Apr 2026 16:31:47 GMT

> [0.1% gate error rate] is still wildly out of reach This is false. When Fowler et al assumed 0.1% gate error rates would be reached for his estimates in 2012 [0], that was ostentatious. Now it's frankly a bit overly conservative. All the big architectures are approaching or surpassing 0.1% gate error rates. From 2022 to 2024, the google team improved mean two qubit gate error rate from 0.6% [1] to 0.4% [2]. Quantinuum's Helios has a two qubit gate error rate of 0.08% [3]. IBM has Heron processors available on their cloud service with two qubit gate error rates ranging from 0.2% to 0.7% [4].…

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Surface codes: Towards practical large-scale quantum computation — mentioned by Strilanc

Sat, 01 Nov 2025 20:02:25 GMT

> The precision in phase needed to perform an accurate QFT scales EXPONENTIALLY with the number of qubits you're trying to transform. This is false. The gates that appear in the textbook QFT circuit (such as the one shown on wikipedia [1]) do mention angles that are exponentially small in N (the number of qubits being operated upon). That may be what's confusing you. But it's well known that the tolerance on those rotations is high, meaning that simply skipping all the exponentially tiny rotations introduces negligible error [2][3]. Here's a simple model. Each time you get a rotation off by…

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Surface codes: Towards practical large-scale quantum computation — mentioned by adgjlsfhk1

Wed, 29 Oct 2025 15:05:57 GMT

https://arxiv.org/pdf/1208.0928 is a pretty good into to surface codes. https://www.nature.com/articles/s41586-024-08449-y is a paper that shows surface codes work on real computers. https://arxiv.org/abs/2505.15917v1 is the most recent costing of factoring various size of N using all the recent papers on optimizing the logical qbit counts.

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Surface codes: Towards practical large-scale quantum computation — mentioned by Strilanc

Mon, 11 Aug 2025 13:36:15 GMT

That paper is hilarious, and is correct that there's plenty of shit to make fun of... but there's also progress. I recommend watching Sam Jacques' talk from PQCrypto 2025 [0]. It would be silly to delay PQC adoption because of focusing on the irrelevant bad papers. In the past ten years, on the theory side, the expected cost of cryptographically relevant quantum factoring has dropped by 1000x [1][2]. On the hardware side, fault tolerance demonstrations have gone from repetition code error rates of 1% error per round [3] to 0.00000001% error per round [fig3a of 4], with full quantum codes…

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Surface codes: Towards practical large-scale quantum computation — mentioned by Strilanc

Wed, 07 Aug 2024 17:12:18 GMT

Quantum/classical is orthogonal to the analog/digital distinction. There are analog quantum computers and digital quantum computers. Analog quantum computers (like annealers) are simpler to make, and they have a lot more play w.r.t. their building blocks when trying to make interesting effects... but ultimately they are limited by noise. Digital quantum computers restrict themselves to finite gate sets, often requiring expensive decompositions to do basic operations (e.g. [1]), but those gates are compatible with error correction so noise can be suppressed arbitrarily (e.g. [2]). It's very…

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Surface codes: Towards practical large-scale quantum computation — mentioned by Strilanc

Mon, 03 Jun 2024 14:12:32 GMT

Wasn't expecting my question to hit top of HN. I guess I'll give some context for why I asked it. I work in quantum error correction, and was trying to collect interesting and quantitative examples of repetition codes being used implicitly in classical systems. Stuff like DRAM storing a 0 or 1 via the presence or absence of 40K electrons [1], undersea cables sending X photons per bit (don't know that one yet), some kind of number for a transistor switching (haven't even decided on the number for that one yet), etc. A key reason quantum computing is so hard is that by default repetition makes…

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Surface codes: Towards practical large-scale quantum computation — mentioned by s1dev

Sat, 16 Apr 2022 09:39:32 GMT

There is an extremely broad range of scaling between linear and exponential… Even in architectures with nearest neighbor gates, the (multiplicative) overhead stemming from error correction will only need to be logarithmic in the size of the computation. The constants may be unfavorable, but a log is still a log. See for example https://arxiv.org/abs/1208.0928 and https://arxiv.org/abs/1310.2984

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Surface codes: Towards practical large-scale quantum computation — HN submission

Thu, 11 Jan 2018 20:55:10 GMT

Surface codes: Towards practical large-scale quantum computation (2012)

1 point; 0 discussion replies on HN. Paper and source history. A submission is not an endorsement.

Surface codes: Towards practical large-scale quantum computation — mentioned by Strilanc

Thu, 30 Apr 2015 17:07:33 GMT

No, there's not only one way. Also, IBM did not invent/discover the layout in question (I think?). The article does tone it down later on, at least: > IBM's design shows the best potential to scale by adding more qubits to arrive at a working quantum system The surface code [0] is a good bet in the which-layout-will-work-first race. Mostly because the existing manufacturing capabilities are limited to working on a surface (as opposed to in 3d), and because the surface code has a good threshold error rate (~1%). John Martinis talked about the surface code in a google tech talk [1]. 0…

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