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Recent constructions of quantum low-density parity-check (QLDPC) codes provide optimal scaling of the number of logical qubits and the minimum distance in terms of the code length, thereby opening the door to fault-tolerant quantum systems…

Quantum Physics · Physics 2024-01-24 Narayanan Rengaswamy , Nithin Raveendran , Ankur Raina , Bane Vasić

Recent developments have shown the existence of quantum low-density parity check (qLDPC) codes with constant rate and linear distance. A natural question concerns the efficient decodability of these codes. In this paper, we present a linear…

Quantum Physics · Physics 2022-06-15 Shouzhen Gu , Christopher A. Pattison , Eugene Tang

We present new upper and lower bounds on the minimum distance of certain generalized bicycle (GB) codes beyond the reach of techniques for classical codes capable of even capturing the true minimum distance for some cases. These bounds are…

We study analytically and numerically decoding properties of finite rate hypergraph-product quantum LDPC codes obtained from random (3,4)-regular Gallager codes, with a simple model of independent X and Z errors. Several non-trival lower…

Quantum Physics · Physics 2018-06-14 Alexey A. Kovalev , Sanjay Prabhakar , Ilya Dumer , Leonid P. Pryadko

For finite length polar codes, channel polarization leaves a significant number of channels not fully polarized. Adding a Cyclic Redundancy Check (CRC) to better protect information on the semi-polarized channels has already been…

Information Theory · Computer Science 2016-11-14 A. Elkelesh , M. Ebada , S. Cammerer , S. ten Brink

Hypergraph product codes are a promising avenue to achieving fault-tolerant quantum computation with constant overhead. When embedding these and other constant-rate qLDPC codes into 2D, a significant number of nonlocal connections are…

Quantum Physics · Physics 2024-05-15 Noah Berthusen , Daniel Gottesman

Quantum low-density parity-check (qLDPC) codes offer a promising route to scalable fault-tolerant quantum computation with constant overhead. Recent advancements have shown that qLDPC codes can outperform the quantum memory capability of…

Quantum Physics · Physics 2024-07-08 Jens Niklas Eberhardt , Vincent Steffan

The usual belief propagation (BP) decoders are, in general, exchanging local information on the Tanner graph of the quantum error-correcting (QEC) code and, in particular, are known to not have a threshold for the surface code. We propose…

Quantum Physics · Physics 2026-03-06 Pedro Hack , Luca Menti , Francisco Lazaro , Alexandru Paler

In this paper, we construct protograph-based spatially coupled low-density parity-check (SC-LDPC) codes by coupling together a series of L disjoint, or uncoupled, LDPC code Tanner graphs into a single coupled chain. By varying L, we obtain…

Information Theory · Computer Science 2016-11-17 David G. M. Mitchell , Michael Lentmaier , Daniel J. Costello

Despite the NP hardness of acquiring minimum distance $d_m$ for linear codes theoretically, in this paper we propose one experimental method of finding minimum-weight codewords, the weight of which is equal to $d_m$ for LDPC codes. One…

Information Theory · Computer Science 2007-10-09 Guangwen Li , Guangzeng Feng

Concatenated bosonic-stabilizer codes have recently gained prominence as promising candidates for achieving low-overhead fault-tolerant quantum computing in the long term. In such systems, analog information obtained from the syndrome…

Quantum Physics · Physics 2025-05-13 Shantom K. Borah , Asit K. Pradhan , Nithin Raveendran , Michele Pacenti , Bane Vasic

The realization of quantum error correction protocols whose logical error rates are suppressed far below physical error rates relies on an intricate combination: the error-correcting code's efficiency, the syndrome extraction circuit's…

Quantum Physics · Physics 2026-03-06 Andrey Boris Khesin , Jonathan Z. Lu

Quantum low-density parity-check (qLDPC) codes can achieve high encoding rates and good code distance scaling, providing a promising route to low-overhead fault-tolerant quantum computing. However, the long-range connectivity required to…

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…

The goal of the paper is to study specific properties of nonbinary low-density parity-check (NB LDPC) codes when used in coded modulation systems. The paper is focused on the practically important NB LDPC codes over extensions of the Galois…

Information Theory · Computer Science 2022-05-25 Irina E. Bocharova , Boris D. Kudryashov , Evgenii P. Ovsyannikov , Vitaly Skachek

In practice, LDPC codes are decoded using message passing methods. These methods offer good performance but tend to converge slowly and sometimes fail to converge and to decode the desired codewords correctly. Recently, tree-reweighted…

Information Theory · Computer Science 2014-03-05 J. Li , R. C. de Lamare , H. Wymeersch

Iterative decoders used for decoding low-density parity-check (LDPC) and moderate-density parity-check (MDPC) codes are not characterized by a deterministic decoding radius and their error rate performance is usually assessed through…

Information Theory · Computer Science 2020-02-27 Paolo Santini , Massimo Battaglioni , Marco Baldi , Franco Chiaraluce

For a quantum error correcting code to be used in practice, it needs to be equipped with an efficient decoding algorithm, which identifies corrections given the observed syndrome of errors.Hypergraph product codes are a promising family of…

Quantum Physics · Physics 2023-11-03 Lev Stambler , Anirudh Krishna , Michael E. Beverland

Error correction at short blocklengths remains a challenge for low-density parity-check (LDPC) codes, as belief propagation (BP) decoding is suboptimal compared to maximum-likelihood decoding (MLD). While BP rarely makes errors, it often…

Information Theory · Computer Science 2025-07-08 Ahmad Ismail , Raphaël Le Bidan , Elsa Dupraz , Charbel Abdel Nour

Quantum LDPC codes may provide a path to build low-overhead fault-tolerant quantum computers. However, as general LDPC codes lack geometric constraints, na\"ive layouts couple many distant qubits with crossing connections which could be…

Quantum Physics · Physics 2022-08-17 Maxime A. Tremblay , Nicolas Delfosse , Michael E. Beverland