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In this work, we introduce a technique for reducing the length of a quantum stabilizer code, and we call this deflation of the code. Deflation can be seen as a generalization of the well-known puncturing and shortening techniques in cases…

In this paper, we report an encoding and decoding method for irregular-quasic-cyclic low-density parity-check (IR-QC-LDPC) codes with multi rates. The algorithm is applicable to parity-check matrices which have dual-diagonal parity…

Information Theory · Computer Science 2019-10-31 Kun Cheng , Qiming Lu , Hongbo Xie , Qi Shen , Shengkai Liao , Chengzhi Peng

Bosonic encodings of quantum information offer hardware-efficient, noise-biased approaches to quantum error correction relative to qubit register encodings. Implementations have focused in particular on error correction of stored, idle…

Quantum Physics · Physics 2025-10-23 Owen C. Wetherbee , Saswata Roy , Baptiste Royer , Valla Fatemi

QAC$^0$ is the class of constant-depth quantum circuits with polynomially many ancillary qubits, where Toffoli gates on arbitrarily many qubits are allowed. In this work, we show that the parity function cannot be computed in QAC$^0$,…

Quantum Physics · Physics 2024-11-11 Ashley Montanaro , Changpeng Shao , Dominic Verdon

Quantum error correction will likely be essential for building a large-scale quantum computer, but it comes with significant requirements at the level of classical control software. In particular, a quantum error-correcting code must be…

Quantum Physics · Physics 2026-04-24 Ewan Murphy , Subhayan Sahu , Michael Vasmer

Motivated by the recent advancement of quantum processors, we investigate quantum approximate optimization algorithm (QAOA) to employ quasi-maximum-likelihood (ML) decoding of classical channel codes. QAOA is a hybrid quantum-classical…

Information Theory · Computer Science 2019-03-07 Toshiki Matsumine , Toshiaki Koike-Akino , Ye Wang

Decoding low-density parity-check codes is critical in many current technologies, such as fifth-generation (5G) wireless networks and satellite communications. The belief propagation algorithm allows for fast decoding due to the low density…

Quantum Physics · Physics 2024-12-12 Sheila M. Perez-Garcia , Ashley Montanaro

We propose a fault-tolerant quantum computation scheme that is broadly applicable to quantum low-density parity-check (qLDPC) codes. The scheme achieves constant qubit overhead and a time overhead of $O(d^{a+o(1)})$ for any $[[n,k,d]]$…

Quantum Physics · Physics 2026-04-14 Guo Zhang , Yuanye Zhu , Ying Li

Quantum error correction (QEC) is considered a deciding component in enabling practical quantum computing. Stabilizer codes, and in particular topological surface codes, are promising candidates for implementing QEC by redundantly encoding…

Quantum Physics · Physics 2025-12-12 Josias Old , Stephan Tasler , Michael J. Hartmann , Markus Müller

Quantum computing with qudits, quantum systems with $d > 2$ levels, offers a powerful extension beyond qubits, expanding the computational possibilities of quantum systems, allowing the simplification of the implementation of several…

Quantum Physics · Physics 2024-10-10 Francesco Pudda , Mario Chizzini , Luca Crippa

Quantum error correction (QEC) is essential for enabling quantum advantages, with decoding as a central algorithmic primitive. Owing to its importance and intrinsic difficulty, substantial effort has been made to QEC decoder design, among…

Quantum Physics · Physics 2026-05-13 Ge Yan , Shanchuan Li , Yuxuan Du

The paradigm of measurement-based quantum computing (MBQC) starts from a highly entangled resource state on which unitary operations are executed through adaptive measurements and corrections ensuring determinism. This is set in contrast to…

Quantum Physics · Physics 2023-11-29 Thierry Nicolas Kaldenbach , Matthias Heller

With the current rate of progress in quantum computing technologies, systems with more than 50 qubits will soon become reality. Computing ideal quantum state amplitudes for circuits of such and larger sizes is a fundamental step to assess…

We study, by means of the stabilizer formalism, a quantum error correcting code which is alternative to the standard block codes since it embeds a qubit into a qudit. The code exploits the non-commutative geometry of discrete phase space to…

Quantum Physics · Physics 2015-06-04 Carlo Cafaro , Federico Maiolini , Stefano Mancini

Given a quantum error correcting code, an important task is to find encoded operations that can be implemented efficiently and fault-tolerantly. In this Letter we focus on topological stabilizer codes and encoded unitary gates that can be…

Quantum Physics · Physics 2013-10-04 Sergey Bravyi , Robert Koenig

In dynamic quantum circuits, classical information from mid-circuit measurements is fed forward during circuit execution. This emerging capability of quantum computers confers numerous advantages that can enable more efficient and powerful…

Quantum Physics · Physics 2024-03-28 Elisa Bäumer , Vinay Tripathi , Alireza Seif , Daniel Lidar , Derek S. Wang

Local decoders, also known as cellular-automaton decoders, offer a promising path toward real-time quantum error correction by replacing centralized classical decoding, with inherent hardware constraints, by a natively parallel and…

Quantum Physics · Physics 2025-09-17 Louis Paletta , Anthony Leverrier , Mazyar Mirrahimi , Christophe Vuillot

We ask what is the general framework for a quantum error correcting code that is defined by a sequence of measurements. Recently, there has been much interest in Floquet codes and space-time codes. In this work, we define and study the…

Quantum Physics · Physics 2025-10-22 Esther Xiaozhen Fu , Daniel Gottesman

The theory of quantum algorithms promises unprecedented benefits of harnessing the laws of quantum mechanics for solving certain computational problems. A persistent obstacle to using such algorithms for solving a wide range of real-world…

The quantum approximate optimization algorithm~(QAOA) first proposed by Farhi et al. promises near-term applications based on its simplicity, universality, and provable optimality. A depth-p QAOA consists of p interleaved unitary…

Quantum Physics · Physics 2019-05-30 Murphy Yuezhen Niu , Sirui Lu , Isaac L. Chuang