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Quantum hardware rarely suffers equal amounts of bit-flip ($X$) and phase-flip ($Z$) errors; one type is often much more common than the other. A code that is ``bias-tailored'' can exploit this imbalance, lowering the fault-tolerance…

Quantum Physics · Physics 2025-07-04 Shixin Wu , Todd A. Brun , Daniel A. Lidar

Quantum error correction (QEC) is critical for practical realization of fault-tolerant quantum computing, and recently proposed families of quantum low-density parity-check (QLDPC) code are prime candidates for advanced QEC hardware…

Information Theory · Computer Science 2025-03-11 Nithin Raveendran , David Declercq , Bane Vasić

With quantum devices rapidly approaching qualities and scales needed for fault tolerance, the validity of simplified error models underpinning the study of quantum error correction needs to be experimentally evaluated. In this work, we have…

Quantum Physics · Physics 2024-12-11 Spiro Gicev , Lloyd C. L. Hollenberg , Muhammad Usman

We propose an architecture for a quantum memory distributed over a $2 \times L$ array of modules equipped with a cyclic shift implemented via flying qubits. The logical information is distributed across the first row of $L$ modules and…

Quantum Physics · Physics 2025-08-05 Edwin Tham , Min Ye , Ilia Khait , John Gamble , Nicolas Delfosse

Due to their fast decoding algorithms, quantum generalizations of low-density parity check, or LDPC, codes have been investigated as a solution to the problem of decoherence in fragile quantum states. However, the additional twisted inner…

Quantum Physics · Physics 2012-07-04 Jacob Farinholt

Constant-rate low-density parity-check (LDPC) codes are promising candidates for constructing efficient fault-tolerant quantum memories. However, if physical gates are subject to geometric-locality constraints, it becomes challenging to…

Quantum Physics · Physics 2025-05-07 Christopher A. Pattison , Anirudh Krishna , John Preskill

We investigate the construction of quantum low-density parity-check (LDPC) codes from classical quasi-cyclic (QC) LDPC codes with girth greater than or equal to 6. We have shown that the classical codes in the generalized…

Quantum Physics · Physics 2010-02-11 Min-Hsiu Hsieh , Todd A. Brun , Igor Devetak

Quantum processors are often affected by biased noise and noisy readout, which reduce reliability and reproducibility. This work combines two complementary strategies to address these challenges. The first is bias tailoring, which aligns…

Quantum Physics · Physics 2025-09-09 Devon Campbell

Quantum error correction offers a promising path for performing quantum computations with low errors. Although a fully fault-tolerant execution of a quantum algorithm remains unrealized, recent experimental developments, along with…

We introduce and analyze a family of Clifford-deformed bivariate bicycle codes that are tailored for biased noise. Our qLDPC codes are defined on a bipartite hexagonal lattice with limited-range gates and low-weight stabilizers. The code is…

Quantum Physics · Physics 2025-06-03 Catherine Leroux , Joseph K. Iverson

We discuss error-correction properties for families of quantum low-density parity check (LDPC) codes with relative distance that tends to zero in the limit of large blocklength. In particular, we show that any family of LDPC codes, quantum…

Quantum Physics · Physics 2013-03-05 Alexey A. Kovalev , Leonid P. Pryadko

Quantum low density parity check (qLDPC) codes, particularly bivariate bicycle (BB) codes, achieve competitive fault tolerance thresholds while offering substantially higher encoding rates than planar surface codes. However, their…

Quantum Physics · Physics 2026-05-07 Nitish Kumar Chandra , Eneet Kaur , Reza Nejabati , Kaushik P. Seshadreesan

Quasi-cyclic (QC) LDPC codes with large girths play a crucial role in several research and application fields, including channel coding, compressed sensing and distributed storage systems. A major challenge in respect of the code…

Information Theory · Computer Science 2026-01-16 Guohua Zhang , Xiangya Liu , Jianhua Zhang , Yi Fang

High-rate bivariate bicycle (BB) codes are promising low-overhead quantum memories, but their stabilizer checks typically have weight $6$ or higher, making syndrome extraction challenging. We introduce subsystem bivariate bicycle (SBB)…

Quantum Physics · Physics 2026-05-07 Zijian Liang , Yu-An Chen

Quantum low-density parity-check codes are a promising approach to fault-tolerant quantum computation, offering potential advantages in rate and decoding efficiency. In this work, we introduce quantum Margulis codes, a new class of QLDPC…

Quantum Physics · Physics 2026-05-13 Michele Pacenti , Dimitris Chytas , Bane Vasic

To build a fault-tolerant quantum computer, it is necessary to implement a quantum error correcting code. Such codes rely on the ability to extract information about the quantum error syndrome while not destroying the quantum information…

Coherent parity check (CPC) codes are a new framework for the construction of quantum error correction codes that encode multiple qubits per logical block. CPC codes have a canonical structure involving successive rounds of bit and phase…

Quantum Physics · Physics 2018-06-08 Joschka Roffe , David Headley , Nicholas Chancellor , Dominic Horsman , Viv Kendon

It is conjectured that quantum computers are able to solve certain problems more quickly than any deterministic or probabilistic computer. A quantum computer exploits the rules of quantum mechanics to speed up computations. However, it is a…

Information Theory · Computer Science 2009-08-15 Salah A. Aly

We study approximate quantum low-density parity-check (QLDPC) codes, which are approximate quantum error-correcting codes specified as the ground space of a frustration-free local Hamiltonian, whose terms do not necessarily commute. Such…

Quantum Physics · Physics 2020-11-13 Thomas C. Bohdanowicz , Elizabeth Crosson , Chinmay Nirkhe , Henry Yuen

Quantum error correction is necessary to perform large-scale quantum computations in the presence of noise and decoherence. As a result, several aspects of quantum error correction have already been explored. These have been primarily…

Quantum Physics · Physics 2021-08-05 Ariel Shlosberg , Anthony M. Polloreno , Graeme Smith