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Quantum LDPC codes promise significant reductions in physical qubit overhead compared with topological codes. However, many existing constructions for performing logical operations come with distance-dependent temporal overheads. We…

Quantum Physics · Physics 2025-10-07 Nouédyn Baspin , Lucas Berent , Lawrence Z. Cohen

Quantum-classical interfaces (QCIs) for fault-tolerant quantum computing must manage simultaneous, real-time decoding across thousands to millions of logical qubits. Scaling these architectures necessitates sharing expensive decoding…

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

Low-density parity-check (LDPC) codes form part of the IRIG-106 standard and have been successfully deployed for the Telemetry Group version of shaped-offset quadrature phase shift keying (SOQPSK-TG) modulation. Recently, LDPC code…

Systems and Control · Electrical Eng. & Systems 2024-10-10 Andrew D. Cummins , David G. M. Mitchell , Erik Perrins

Quantum low-density parity-check (qLDPC) codes can encode many logical qubits within a single code block at low physical qubit overhead, yet magic state injection into such codes remains largely underexplored. Existing state injection…

Quantum Physics · Physics 2026-04-08 Kun Liu , Shifan Xu , Tomas Jochym-O'Connor , Zhiyang He , Shraddha Singh , Yongshan Ding

We report on the fault-tolerant operation of logical qubits on a neutral atom quantum computer, with logical performance surpassing physical performance for multiple circuits including Bell states (12x error reduction), random circuits…

Low-density parity-check (LDPC) coding for a multitude of equal-capacity channels is studied. First, based on numerous observations, a conjecture is stated that when the belief propagation decoder converges on a set of equal-capacity…

Information Theory · Computer Science 2016-11-17 Ali Sanaei , Mahdi Ramezani , Masoud Ardakani

Quantum low-density parity-check (QLDPC) codes provide a practical balance between error-correction capability and implementation complexity in quantum error correction (QEC). In this paper, we propose an algebraic construction based on…

Information Theory · Computer Science 2026-01-14 Alessio Baldelli , Massimo Battaglioni , Jonathan Mandelbaum , Sisi Miao , Laurent Schmalen

Multi-qubit parity measurements are essential to quantum error correction. Current realizations of these measurements often rely on ancilla qubits, a method that is sensitive to faulty two-qubit gates and which requires significant…

Quantum Physics · Physics 2018-12-12 Baptiste Royer , Shruti Puri , Alexandre Blais

Quantum error correction is essential for reliable quantum computation, where surface codes demonstrate high fault-tolerant thresholds and hardware efficiency. However, noise in single-shot measurements limits logical readout fidelity,…

Quantum Physics · Physics 2025-05-13 Xiao-Yue Xu , Chen Ding , Wan-Su Bao

Error correction allows a quantum computer to preserve states long beyond the decoherence time of its physical qubits. Key to any scheme of error correction is the decoding algorithm, which estimates the error state of qubits from the…

Quantum Physics · Physics 2025-01-06 Stasiu Wolanski , Ben Barber

Low Density Parity Check (LDPC) codes are linear error correcting codes used in communication systems for Forward Error Correction (FEC). But, intensive computation is required for encoding and decoding of LDPC codes, making it difficult…

Distributed, Parallel, and Cluster Computing · Computer Science 2022-01-13 Bhargav Gokalgandhi , Ivan Seskar

Quantum Tanner codes constitute a family of quantum low-density parity-check (LDPC) codes with good parameters, i.e., constant encoding rate and relative distance. In this article, we prove that quantum Tanner codes also facilitate…

Quantum Physics · Physics 2024-04-15 Shouzhen Gu , Eugene Tang , Libor Caha , Shin Ho Choe , Zhiyang He , Aleksander Kubica

We consider spatially coupled low-density parity-check codes with finite smoothing parameters. A finite smoothing parameter is important for designing practical codes that are decoded using low-complexity windowed decoders. By optimizing…

Information Theory · Computer Science 2017-01-27 Laurent Schmalen , Vahid Aref , Fanny Jardel

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

We present an experimental procedure to determine the usefulness of a measurement scheme for quantum error correction (QEC). A QEC scheme typically requires the ability to prepare entangled states, to carry out multi-qubit measurements, and…

Quantum Physics · Physics 2015-06-04 Gabrielle Denhez , Alexandre Blais , David Poulin

This paper proposes a "quasi-synchronous" design approach for signal processing circuits, in which timing violations are permitted, but without the need for a hardware compensation mechanism. The case of a low-density parity-check (LDPC)…

Information Theory · Computer Science 2017-11-21 François Leduc-Primeau , Frank R. Kschischang , Warren J. Gross

In this paper, we give necessary and sufficient conditions for low-density parity-check (LDPC) codes with column-weight three to correct three errors when decoded using hard-decision message-passing decoding. Additionally, we give necessary…

Information Theory · Computer Science 2009-09-29 Shashi Kiran Chilappagari , Anantha Raman Krishnan , Bane Vasic , Michael W. Marcellin

Parity measurement is a central tool to many quantum information processing tasks. In this Letter, we propose a method to directly measure two- and four-qubit parity with low overhead in hard- and software, while remaining robust to…

A variation of low density parity check (LDPC) error correcting codes defined over Galois fields ($GF(q)$) is investigated using statistical physics. A code of this type is characterised by a sparse random parity check matrix composed of…

Statistical Mechanics · Physics 2009-10-31 Kazutaka Nakamura , Yoshiyuki Kabashima , David Saad