Decoder Switching: Breaking the Speed-Accuracy Tradeoff in Real-Time Quantum Error Correction

Fuente: arXiv
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Autores principales: Toshio, Riki, Kishi, Kaito, Fujisaki, Jun, Oshima, Hirotaka, Sato, Shintaro, Fujii, Keisuke
Formato: Preprint
Publicado: 2025
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author Toshio, Riki
Kishi, Kaito
Fujisaki, Jun
Oshima, Hirotaka
Sato, Shintaro
Fujii, Keisuke
author_facet Toshio, Riki
Kishi, Kaito
Fujisaki, Jun
Oshima, Hirotaka
Sato, Shintaro
Fujii, Keisuke
contents The realization of fault-tolerant quantum computers hinges on the construction of high-speed, high-accuracy, real-time decoding systems. The persistent challenge lies in the fundamental trade-off between speed and accuracy: efforts to improve the decoder's accuracy often lead to unacceptable increases in decoding time and hardware complexity, while attempts to accelerate decoding result in a significant degradation in logical error rate. To overcome this challenge, we propose a novel framework, decoder switching, which balances these competing demands by combining a faster, soft-output decoder ("weak decoder") with a slower, high-accuracy decoder ("strong decoder"). In usual rounds, the weak decoder processes error syndromes and simultaneously evaluates its reliability via soft information. Only when encountering a decoding window with low reliability do we switch to the strong decoder to achieve more accurate decoding. Numerical simulations suggest that this framework can achieve accuracy comparable to, or even surpassing, that of the strong decoder, while maintaining an average decoding time on par with the weak decoder. We also develop an online decoding scheme tailored to our framework, named double window decoding, and elucidate the criteria for preventing an exponential slowdown of quantum computation. These findings break the long-standing speed-accuracy trade-off, paving the way for scalable real-time decoding devices.
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id arxiv_https___arxiv_org_abs_2510_25222
institution arXiv
publishDate 2025
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spellingShingle Decoder Switching: Breaking the Speed-Accuracy Tradeoff in Real-Time Quantum Error Correction
Toshio, Riki
Kishi, Kaito
Fujisaki, Jun
Oshima, Hirotaka
Sato, Shintaro
Fujii, Keisuke
Quantum Physics
The realization of fault-tolerant quantum computers hinges on the construction of high-speed, high-accuracy, real-time decoding systems. The persistent challenge lies in the fundamental trade-off between speed and accuracy: efforts to improve the decoder's accuracy often lead to unacceptable increases in decoding time and hardware complexity, while attempts to accelerate decoding result in a significant degradation in logical error rate. To overcome this challenge, we propose a novel framework, decoder switching, which balances these competing demands by combining a faster, soft-output decoder ("weak decoder") with a slower, high-accuracy decoder ("strong decoder"). In usual rounds, the weak decoder processes error syndromes and simultaneously evaluates its reliability via soft information. Only when encountering a decoding window with low reliability do we switch to the strong decoder to achieve more accurate decoding. Numerical simulations suggest that this framework can achieve accuracy comparable to, or even surpassing, that of the strong decoder, while maintaining an average decoding time on par with the weak decoder. We also develop an online decoding scheme tailored to our framework, named double window decoding, and elucidate the criteria for preventing an exponential slowdown of quantum computation. These findings break the long-standing speed-accuracy trade-off, paving the way for scalable real-time decoding devices.
title Decoder Switching: Breaking the Speed-Accuracy Tradeoff in Real-Time Quantum Error Correction
topic Quantum Physics
url https://arxiv.org/abs/2510.25222