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Quantum error correction is rapidly seeing first experimental implementations, but there is a significant gap between asymptotically optimal error-correcting codes and codes that are experimentally feasible. Quantum LDPC codes range from…

It is generally unclear whether smaller codes can be "concatenated" to systematically create quantum LDPC codes or their sparse subsystem code cousins where the degree of the Tanner graph remains bounded while increasing the code distance.…

Quantum Physics · Physics 2025-07-21 ChunJun Cao , Brad Lackey

A powerful method for analyzing quantum error-correcting codes is to map them onto classical statistical mechanics models. Such mappings have thus far mostly focused on static codes, possibly subject to repeated syndrome measurements.…

Quantum Physics · Physics 2026-02-19 Cory T. Aitchison , Benjamin Béri

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

The CSS code construction is a powerful framework used to express features of a quantum code in terms of a pair of underlying classical codes. Its subsystem extension allows for similar expressions, but the general case has not been fully…

Quantum Physics · Physics 2024-07-17 Michael Liaofan Liu , Nathanan Tantivasadakarn , Victor V. Albert

We introduce a technique that uses gauge fixing to significantly improve the quantum error correcting performance of subsystem codes. By changing the order in which check operators are measured, valuable additional information can be…

Quantum Physics · Physics 2021-10-18 Oscar Higgott , Nikolas P. Breuckmann

Hypergraph product codes introduced by Tillich and Z\'emor are a class of quantum LDPC codes with constant rate and distance scaling with the square-root of the block size. Quantum expander codes, a subclass of these codes, can be decoded…

Quantum Physics · Physics 2019-05-03 Antoine Grospellier , Anirudh Krishna

Divisible codes are defined by the property that codeword weights share a common divisor greater than one. They are used to design signals for communications and sensing, and this paper explores how they can be used to protect quantum…

Quantum Physics · Physics 2022-04-29 Jingzhen Hu , Qingzhong Liang , Robert Calderbank

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

Tensor-network codes enable the construction of large stabilizer codes out of tensors describing smaller stabilizer codes. An application of tensor-network codes was an efficient and exact decoder for holographic codes. Here, we show how to…

Quantum Physics · Physics 2022-04-27 Terry Farrelly , David K. Tuckett , Thomas M. Stace

Spatially-coupled (SC) codes is a class of convolutional LDPC codes that has been well investigated in classical coding theory thanks to their high performance and compatibility with low-latency decoders. We describe toric codes as quantum…

Quantum Physics · Physics 2025-04-09 Siyi Yang , Robert Calderbank

We construct a three-dimensional Calderbank-Shor-Steane (CSS) stabilizer code on the Face-Centered Cubic (FCC) lattice. Physical qubits reside on the edges of the lattice (coordination $K=12$); X-stabilizers act on octahedral voids and…

Quantum Physics · Physics 2026-03-24 Raghu Kulkarni

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 low density parity check (qLDPC) codes are an attractive alternative to the surface code due to their relatively high code rate and distance. However, unlike the surface code which has simple, geometrically local, stabilizer checks,…

Quantum Physics · Physics 2025-09-17 Omprakash Chandra , Gopikrishnan Muraleedharan , Gavin K. Brennen

We study the performance of medium-length quantum LDPC (QLDPC) codes in the depolarizing channel. Only degenerate codes with the maximal stabilizer weight much smaller than their minimum distance are considered. It is shown that with the…

Quantum Physics · Physics 2021-11-24 Pavel Panteleev , Gleb Kalachev

We study the hardness of the problem of finding the distance of quantum error-correcting codes. The analogous problem for classical codes is known to be NP-hard, even in approximate form. For quantum codes, various problems related to…

Quantum Physics · Physics 2023-11-07 Upendra Kapshikar , Srijita Kundu

Unlike the surface code, quantum low-density parity-check (QLDPC) codes can have a finite encoding rate, potentially lowering the error correction overhead. However, finite-rate QLDPC codes have nonlocal stabilizers, making it difficult to…

Quantum Physics · Physics 2025-02-03 Argyris Giannisis Manes , Jahan Claes

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…

In this paper, we introduce the gauge-fixed QLDPC surgery scheme, an improved logical measurement scheme based on the construction of Cohen et al. (Sci. Adv. 8, eabn1717). Our scheme leverages expansion properties of the Tanner graph to…

Quantum Physics · Physics 2025-10-29 Andrew W. Cross , Zhiyang He , Patrick J. Rall , Theodore J. Yoder

Fault-tolerant syndrome extraction is a key ingredient in implementing fault-tolerant quantum computations. While conventional methods use a number of extra qubits linear in the weight of the syndrome, several improvements have been…

Quantum Physics · Physics 2024-02-22 Benjamin Anker , Milad Marvian