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arXiv:1905.09749quant-ph

How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits

Craig Gidney, Martin Ekerå

Abstract

We significantly reduce the cost of factoring integers and computing discrete logarithms in finite fields on a quantum computer by combining techniques from Shor 1994, Griffiths-Niu 1996, Zalka 2006, Fowler 2012, Ekerå-Håstad 2017, Ekerå 2017, Ekerå 2018, Gidney-Fowler 2019, Gidney 2019. We estimate the approximate cost of our construction using plausible physical assumptions for large-scale superconducting qubit platforms: a planar grid of qubits with nearest-neighbor connectivity, a characteristic physical gate error rate of $10^{-3}$, a surface code cycle time of 1 microsecond, and a reaction time of 10 microseconds. We account for factors that are normally ignored such as noise, the need to make repeated attempts, and the spacetime layout of the computation. When factoring 2048 bit RSA integers, our construction's spacetime volume is a hundredfold less than comparable estimates from earlier works (Van Meter et al. 2009, Jones et al. 2010, Fowler et al. 2012, Gheorghiu et al. 2019). In the abstract circuit model (which ignores overheads from distillation, routing, and error correction) our construction uses $3 n + 0.002 n \lg n$ logical qubits, $0.3 n^3 + 0.0005 n^3 \lg n$ Toffolis, and $500 n^2 + n^2 \lg n$ measurement depth to factor $n$-bit RSA integers. We quantify the cryptographic implications of our work, both for RSA and for schemes based on the DLP in finite fields.

arXiv comments
31 pages, 9 figures, 5 tables
Journal reference
Quantum 5, 433 (2021)
DOI
doi:10.22331/q-2021-04-15-433
Subjects
quant-phQuantum Physics

On Hacker News

Linked by 12 identifiable commenters in 15 comments across 15 threads, from May 2019 to Mar 2026. Found in 7 HN submissions from May 2019 to Jan 2023. Open submission discussions.

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Discussed in comments15 threads

    • You can save time by first looking at the required noise performance of these schemes. From the abstract of the paper: >On superconducting architectures with 10−3 physical error rates... So good old 0.1% noise performance again. That seems to have come from the "20 million noisy…

      upofadownView on HNParent context

    • > 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…

      StrilancView on HNParent context

    • > Is there some minimum number of qubits at which some minimum viable quantum-supreme task can theoretically be achieved? That is a very broad range of possibilities, so allow me to narrow it to cryptography. I am by no means an expert on this, but I spent the weekend reading…

      ryaoView on HNParent context

    • We don’t need exponentially more physical qubits because we have quantum error correction schemes that exponentially decrease the logical error rate with only a polynomial increase in the number of qubits. There are in fact many schemes for this (https://errorcorrectionzoo.org/)…

      wzengView on HNParent context

  1. Willow, Our Quantum Chip 1 comment
    • You need to distinguish between "physical qubits" and "logical qubits." This paper creates a single "first-of-a-kind" logical qubit with about 100 physical qubits (using Surface Code quantum error correction). A paper from Google in 2019 estimates needing ~20 million physical…

      qnleighView on HNParent context

    • https://scottaaronson.blog/?p=8310 suggests perhaps the next decade for useful quantum computer. this suggests the scale for RSA2048: https://arxiv.org/pdf/1905.09749 The thing about this bet is you don't have to pay until 2048 whereas I have to pay as soon as it happens and…

      amirhirschView on HNParent context

    • > If current quantum computers were scaled up to more qubits That depends on what you mean by "scaled up". There is a concept of "Quantum Volume" that exists, which basically means the depth of the longest qubit circuit you can pull off.…

      archgoonView on HNParent context

    • Related: https://arxiv.org/abs/1905.09749 | How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits

      upofadownView on HNParent context

    • A 5-qubit code corrects against single qubit errors. You could say a factor of 5 is a lower bound. In more technical terms, this scheme fixes all weight-1 errors. More realistically [1], you'd have a factor of around 1,600 for a distance-27 code. [1]…

      reikonomushaView on HNParent context

    • Gidney and Ekerå have you covered: https://arxiv.org/abs/1905.09749 Short answer, this probably won't even register as a pitstop on the technical pathway.

      bnjemianView on HNParent context

  2. The radix 2^51 trick (2017) 1 comment
    • In hardware this would be called a carry save adder [1]. One interesting fact about carry save adders is that the carry part of the register can be extended in order to avoid any carrying between words for very long periods of time. Instead of using 53 bits to represent 52 bits…

      StrilancView on HNParent context

    • Google's new quantum supremacy device has 1,113 single-qubit gates and 430 two-qubit gates. Article "How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits" https://arxiv.org/abs/1905.09749 shows how to significantly reduce the cost of factoring integers…

      nabla9View on HNParent context

    • You are way off. Google's new quantum supremacy device has 1,113 single-qubit gates and 430 two-qubit gates. Consider recent improvement in RSA factorization "How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits" https://arxiv.org/abs/1905.09749 Actual…

      nabla9View on HNParent context

    • "How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits" https://arxiv.org/abs/1905.09749

      grublesView on HNParent context

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