High-Girth QLDPC Codes from Circulant and Affine Permutation Matrices
Abstract
We study two explicit constructions of binary Calderbank--Shor--Steane quantum low-density parity-check (QLDPC) codes with check weight six. The first uses a fixed circulant shift pattern and yields parameters code6N2N+26 with Tanner graph girth twelve for N=31 and every N≥37. A graph incidence interpretation gives the ranks and girths, and a uniform weight six logical operator establishes the exact distance. The second construction uses fixed matrix polynomials with circulant and affine permutation coefficients. Here, a polynomial commutation identity guarantees orthogonality for every cyclic lift. Four realizations give $[[192,16,8]]$, $[[288,16,12]]$, $[[384,16,14]]$, and $[[576,32,20]]$, with Tanner girth eight and computationally certified distances. We give reproducible construction data, distinguish classical cycle distance from quantum distance, and identify the limitations of both families.
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BibTeX
@misc{nourozi2026highgirth,
title = {{High-Girth QLDPC Codes from Circulant and Affine Permutation Matrices}},
author = {Vahid Nourozi and Roxana Smarandache and David G. M. Mitchell†},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.19451},
eprint = {2610.19451},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.19451},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - High-Girth QLDPC Codes from Circulant and Affine Permutation Matrices
AU - Vahid Nourozi
AU - Roxana Smarandache
AU - David G. M. Mitchell†
PY - 2026
DA - 2026/10/14
PB - arXiv
DO - 10.48550/arxiv.2610.19451
UR - https://arxiv.org/abs/2610.19451
AB - We study two explicit constructions of binary Calderbank--Shor--Steane quantum low-density parity-check (QLDPC) codes with check weight six. The first uses a fixed circulant shift pattern and yields parameters code6N2N+26 with Tanner graph girth twelve for N=31 and every N≥37. A graph incidence interpretation gives the ranks and girths, and a uniform weight six logical operator establishes the exact distance. The second construction uses fixed matrix polynomials with circulant and affine permutation coefficients. Here, a polynomial commutation identity guarantees orthogonality for every cyclic lift. Four realizations give $[[192,16,8]]$, $[[288,16,12]]$, $[[384,16,14]]$, and $[[576,32,20]]$, with Tanner girth eight and computationally certified distances. We give reproducible construction data, distinguish classical cycle distance from quantum distance, and identify the limitations of both families.
ER -