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Historically, a $\sqrt{N}log^{1/2}(N)$ distance barrier for quantum low-density parity-check (LDPC) codes with $N$ qubits persisted for nearly two decades, until the recent discovery of the fibre-bundle code. An open question is whether…

Quantum Physics · Physics 2025-07-22 Guanyu Zhu

Spatially-Coupled (SC)-LDPC codes are known to have outstanding error-correction performance and low decoding latency. Whereas previous works on LDPC and SC-LDPC codes mostly take either an asymptotic or a finite-length design approach, in…

Information Theory · Computer Science 2022-09-02 Homa Esfahanizadeh , Eshed Ram , Yuval Cassuto , Lara Dolecek

Classical low-density parity-check (LDPC) codes are a widely deployed and well-established technology, forming the backbone of modern communication and storage systems. It is well known that, in this classical setting, increasing the girth…

Quantum Physics · Physics 2026-01-21 Kenta Kasai

Quantum error correction (QEC) is critical for scalable and reliable quantum computing, but existing solutions, such as surface codes, incur significant qubit overhead. Quantum low-density parity check (qLDPC) codes have recently emerged as…

Quantum low-density parity check (qLDPC) codes offer higher encoding rate than topological codes, e.g. surface codes, making them favourable for practical, fault-tolerant quantum computing with low overhead. These codes are particularly…

Quantum Physics · Physics 2025-09-23 Susan X. Chen , Matthias C. Löbl , Ming Lai Chan , Anders S. Sørensen , Stefano Paesani

In this work, we construct the first locally-correctable codes (LCCs), and locally-testable codes (LTCs) with constant rate, constant relative distance, and sub-polynomial query complexity. Specifically, we show that there exist binary LCCs…

Computational Complexity · Computer Science 2015-04-23 Swastik Kopparty , Or Meir , Noga Ron-Zewi , Shubhangi Saraf

Quantum low-density parity-check (qLDPC) codes can be implemented by measuring only low-weight checks, making them compatible with noisy quantum hardware and central to the quest to build noise-resilient quantum computers. A fundamental…

Quantum Physics · Physics 2026-01-23 Lily Wang , Andy Zeyi Liu , Ray Li , Aleksander Kubica , Shouzhen Gu

In this paper, we analyze the finite-length performance of codes on graphs constructed by connecting spatially coupled low-density parity-check (SC-LDPC) code chains. Successive (peeling) decoding is considered for the binary erasure…

Information Theory · Computer Science 2014-03-03 Pablo M. Olmos , David G. M. Mitchell , Dmitri Truhachev , Daniel J. Costello

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

The surface code is a promising candidate for fault-tolerant quantum computation and has been implemented in many quantum hardware platforms. In this work, we propose a new non-local unitary circuit to encode a surface code state based on a…

Quantum Physics · Physics 2025-06-05 Pei-Kai Tsai , Shruti Puri

Distributing circuits across quantum processor modules will enable the execution of circuits larger than the qubit count limitations of monolithic processors. While distributed quantum computation has primarily utilized circuit cutting, it…

Quantum error correction is an indispensable ingredient for scalable quantum computing. In this Perspective we discuss a particular class of quantum codes called low-density parity-check (LDPC) quantum codes. The codes we discuss are…

Quantum Physics · Physics 2021-10-26 Nikolas P. Breuckmann , Jens Niklas Eberhardt

Continuous variable quantum key distribution bears the promise of simple quantum key distribution directly compatible with commercial off the shelf equipment. However, for a long time its performance was hindered by the absence of good…

Quantum Physics · Physics 2025-06-18 Jesus Martinez-Mateo , David Elkouss

We propose a method for constructing quantum error-correcting codes based on non-binary low-density parity-check codes with Tanner graph girth 16. While conventional constructions using circulant permutation matrices are limited to girth…

Quantum Physics · Physics 2025-04-29 Kenta Kasai

In fault-tolerant quantum computing, quantum algorithms are implemented through quantum circuits capable of error correction. These circuits are typically constructed based on specific quantum error correction codes, with consideration…

Quantum Physics · Physics 2025-03-13 Ying Li

We investigate the non-nearest-neighbor interaction effect in 1-D spin-1/2 chain model. In many previous schemes this long-range coupling is omitted because of its relative weak strength compared with the nearest-neighbor coupling. We show…

Quantum Physics · Physics 2009-11-13 Yong Hu , Zheng-Wei Zhou , Guang-Can Guo

This paper proposes a method for designing error correction codes by combining a known coding scheme with an autoencoder. Specifically, we integrate an LDPC code with a trained autoencoder to develop an error correction code for intractable…

Information Theory · Computer Science 2020-03-03 Eren Balevi , Jeffrey G. Andrews

Although two-qubit entangling gates are necessary for universal quantum computing, they are notoriously difficult to implement with high fidelity. Recently, tunable couplers have become a key component for realizing high-fidelity two-qubit…

Quantum Physics · Physics 2022-09-28 Hayato Goto

Iterative decoders for finite length quantum low-density parity-check (QLDPC) codes are attractive because their hardware complexity scales only linearly with the number of physical qubits. However, they are impacted by short cycles,…

Information Theory · Computer Science 2021-10-20 Nithin Raveendran , Bane Vasić

As systems for quantum computing keep growing in size and number of qubits, challenges in scaling the control capabilities are becoming increasingly relevant. Efficient schemes to simultaneously mediate coherent interactions between…