An almost-linear time decoding algorithm for quantum LDPC codes under circuit-level noise

Fuente: arXiv
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Auteurs principaux: iOlius, Antonio deMarti, Martinez, Imanol Etxezarreta, Roffe, Joschka, Martinez, Josu Etxezarreta
Format: Preprint
Publié: 2024
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author iOlius, Antonio deMarti
Martinez, Imanol Etxezarreta
Roffe, Joschka
Martinez, Josu Etxezarreta
author_facet iOlius, Antonio deMarti
Martinez, Imanol Etxezarreta
Roffe, Joschka
Martinez, Josu Etxezarreta
contents Fault-tolerant quantum computers must be designed in conjunction with classical co-processors that decode quantum error correction measurement information in real-time. In this work, we introduce the belief propagation plus ordered Tanner forest (BP+OTF) algorithm as an almost-linear time decoder for quantum low-density parity-check codes. The OTF post-processing stage removes qubits from the decoding graph until it has a tree-like structure. Provided that the resultant loop-free OTF graph supports a subset of qubits that can generate the syndrome, BP decoding is then guaranteed to converge. To enhance performance under circuit-level noise, we introduce a technique for sparsifying detector error models. This method uses a transfer matrix to map soft information from the full detector graph to the sparsified graph, preserving critical error propagation information from the syndrome extraction circuit. Our BP+OTF implementation first applies standard BP to the full detector graph, followed by BP+OTF post-processing on the sparsified graph. Numerical simulations show that the BP+OTF decoder achieves similar logical error suppression compared to state-of-the-art inversion-based and matching decoders for bivariate bicycle and surface codes, respectively, while maintaining almost-linear runtime complexity across all stages.
format Preprint
id arxiv_https___arxiv_org_abs_2409_01440
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle An almost-linear time decoding algorithm for quantum LDPC codes under circuit-level noise
iOlius, Antonio deMarti
Martinez, Imanol Etxezarreta
Roffe, Joschka
Martinez, Josu Etxezarreta
Quantum Physics
Fault-tolerant quantum computers must be designed in conjunction with classical co-processors that decode quantum error correction measurement information in real-time. In this work, we introduce the belief propagation plus ordered Tanner forest (BP+OTF) algorithm as an almost-linear time decoder for quantum low-density parity-check codes. The OTF post-processing stage removes qubits from the decoding graph until it has a tree-like structure. Provided that the resultant loop-free OTF graph supports a subset of qubits that can generate the syndrome, BP decoding is then guaranteed to converge. To enhance performance under circuit-level noise, we introduce a technique for sparsifying detector error models. This method uses a transfer matrix to map soft information from the full detector graph to the sparsified graph, preserving critical error propagation information from the syndrome extraction circuit. Our BP+OTF implementation first applies standard BP to the full detector graph, followed by BP+OTF post-processing on the sparsified graph. Numerical simulations show that the BP+OTF decoder achieves similar logical error suppression compared to state-of-the-art inversion-based and matching decoders for bivariate bicycle and surface codes, respectively, while maintaining almost-linear runtime complexity across all stages.
title An almost-linear time decoding algorithm for quantum LDPC codes under circuit-level noise
topic Quantum Physics
url https://arxiv.org/abs/2409.01440