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Related papers: Low Rate Protograph-Based LDPC Codes for Continuou…

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This paper presents novel techniques for improving the error correction performance and reducing the complexity of coarsely quantized 5G-LDPC decoders. The proposed decoder design supports arbitrary message-passing schedules on a…

Information Theory · Computer Science 2025-08-19 Philipp Mohr , Gerhard Bauch

We investigate the optimization of epsilon-security parameters in quantum key distribution (QKD), aiming to improve the achievable secure key rate under a fixed overall composable security level. For this purpose, we employ a continuous…

Quantum Physics · Physics 2025-12-23 Alexander G. Mountogiannakis , Stefano Pirandola

Real-time decoding is crucial for fault-tolerant quantum computing but likely requires specialized hardware such as field-programmable gate arrays (FPGAs), whose parallelism can alter relative algorithmic performance. We analyze…

Quantum Physics · Physics 2026-01-27 Satvik Maurya , Thilo Maurer , Markus Bühler , Drew Vandeth , Michael E. Beverland

Standard protocols for quantum key distribution (QKD) require that the sender be able to transmit in two or more mutually unbiased bases. Here, we analyze the extent to which the performance of QKD is degraded by diffraction effects that…

Rate-adaptive MacKay-Neal (MN) codes based on protographs are analyzed. The code construction employs an outer distribution matcher (DM) to adapt the rate of the scheme. The DM is coupled with an inner protograph-based low-density…

Information Theory · Computer Science 2025-10-17 Ayman Zahr , Emna Ben Yacoub , Balázs Matuz , Gianluigi Liva

Key-value (KV) cache compression has emerged as a critical technique for reducing the memory and latency overhead of autoregressive language models during inference. Prior approaches predominantly rely on query-key attention scores to rank…

Computation and Language · Computer Science 2025-09-19 Ayan Sengupta , Siddhant Chaudhary , Tanmoy Chakraborty

Quantum key distribution (QKD) allows for communication with security guaranteed by quantum theory. The main theoretical problem in QKD is to calculate the secret key rate for a given protocol. Analytical formulas are known for protocols…

Quantum Physics · Physics 2016-05-24 Patrick J. Coles , Eric M. Metodiev , Norbert Lütkenhaus

Quantum low-density parity-check codes are promising candidates towards scalable fault-tolerant quantum computation. Among these, bivariate bicycle (BB) codes offer superior encoding rates and large code distance compared to surface codes.…

We point out a critical flaw in the analysis of Quantum Key Distribution (QKD) protocols that employ the two-way error correction protocol Cascade. Specifically, this flaw stems from an incom-plete consideration of all two-way communication…

Quantum Physics · Physics 2023-12-27 Devashish Tupkary , Norbert Lütkenhaus

In this paper, we study a compute-and-forward (CAF) relaying scheme with low-density parity-check (LDPC) codes, a special case of physical layer network coding, under the quadrature phase shift keying (QPSK) modulation. The novelty of this…

Information Theory · Computer Science 2019-04-18 Satoshi Takabe , Tadashi Wadayama , Ángeles Vazquez-Castro , Masahito Hayashi

The design of low-density parity-check (LDPC) code ensembles optimized for a finite number of decoder iterations is investigated. Our approach employs EXIT chart analysis and differential evolution to design such ensembles for the binary…

Information Theory · Computer Science 2016-11-17 Ian P. Mulholland , Enrico Paolini , Mark F. Flanagan

We introduce Decision Tree Decoders (DTDs), which rely only on the sparsity of the binary check matrix, making them broadly applicable for decoding any quantum low-density parity-check (qLDPC) code and fault-tolerant quantum circuits. DTDs…

Quantum Physics · Physics 2025-02-25 Kai R. Ott , Bence Hetényi , Michael E. Beverland

Continuous-variable quantum key distribution (CV-QKD) enables information-theoretically secure key generation between legitimate parties. To further enhance system performance, an improved two-way CV-QKD protocol has been proposed, which is…

Quantum Physics · Physics 2026-01-28 Yanhao Sun , Jiayu Ma , Xiangyu Wang , Song Yu , Ziyang Chen , Hong Guo

Decoy-state quantum key distribution (QKD) is undoubtedly the most efficient solution to handle multi-photon signals emitted by laser sources, and provides the same secret key rate scaling as ideal single-photon sources. It requires,…

Quantum Physics · Physics 2023-12-22 Xoel Sixto , Guillermo Currás-Lorenzo , Kiyoshi Tamaki , Marcos Curty

Block-fading (BF) channel, also known as slow-fading channel, is a type of simple and practical channel model that can characterize the primary feature of a number of wireless-communication applications with low to moderate mobility.…

Information Theory · Computer Science 2021-07-22 Yi Fang , Pingping Chen , Guofa Cai , Francis C. M. Lau , Soung Chang Liew , Guojun Han

We present a theory of quantum serial turbo-codes, describe their iterative decoding algorithm, and study their performances numerically on a depolarization channel. Our construction offers several advantages over quantum LDPC codes. First,…

Quantum Physics · Physics 2009-06-10 David Poulin , Jean-Pierre Tillich , Harold Ollivier

Quantum low-density parity-check (qLDPC) codes are promising for realizing scalable fault-tolerant quantum computation due to their potential for low-overhead protocols. A common approach to decoding qLDPC codes is to use the belief…

Quantum Physics · Physics 2025-10-13 Kento Tsubouchi , Hayata Yamasaki , Shiro Tamiya

We experimentally demonstrated a sub-Mbps key rate Gaussian-modulated coherent-state continuous-variable quantum key distribution (CV-QKD) over 100 km transmission distance. To efficiently control the excess noise, the quantum signal and…

Quantum Physics · Physics 2023-04-12 Yaodi Pi , Heng Wang , Yan Pan , Yun Shao , Yang Li , Jie Yang , Yichen Zhang , Wei Huang , Bingjie Xu

Efficient and high-performance quantum error correction is essential for achieving fault-tolerant quantum computing. Low-depth random circuits offer a promising approach to identifying effective and practical encoding strategies. In this…

Quantum Physics · Physics 2026-03-02 Guoding Liu , Zhenyu Du , Zi-Wen Liu , Xiongfeng Ma

In this paper, we compare the finite-length performance of protograph-based spatially coupled low-density parity-check (SC-LDPC) codes and LDPC block codes (LDPC-BCs) over GF(q). In order to reduce computational complexity and latency, a…

Information Theory · Computer Science 2014-08-13 Kechao Huang , David G. M. Mitchell , Lai Wei , Xiao Ma , Daniel J. Costello