,
Venkatesan Guruswami
Creative Commons Attribution 4.0 International license
The first linear-distance quantum LDPC codes were recently constructed by a line of breakthrough works (culminating in the result of Panteleev & Kalachev, 2021). All such constructions, even when allowing for almost-linear distance, are based on an operation called a balanced (or lifted) product, which is used in a one-shot manner to combine a pair of large classical codes possessing a group symmetry.
We present a new construction of almost-linear distance quantum LDPC codes that is iterative in nature. Our construction is based on a more basic and widely used product, namely the homological product (i.e. the tensor product of chain complexes).
Specifically, for every ε > 0, we obtain a family of [[N,N^{1-ε},N^{1-ε}]] (subsystem) quantum LDPC codes via repeated homological products of a constant-sized quantum locally testable code. Our key idea is to remove certain low-weight codewords using subsystem codes (while still maintaining constant stabilizer weight), in order to circumvent a particular obstruction that limited the distance of many prior homological product code constructions to at most Õ(√N).
@InProceedings{golowich_et_al:LIPIcs.CCC.2025.25,
author = {Golowich, Louis and Guruswami, Venkatesan},
title = {{Quantum LDPC Codes of Almost Linear Distance via Iterated Homological Products}},
booktitle = {40th Computational Complexity Conference (CCC 2025)},
pages = {25:1--25:11},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-379-9},
ISSN = {1868-8969},
year = {2025},
volume = {339},
editor = {Srinivasan, Srikanth},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CCC.2025.25},
URN = {urn:nbn:de:0030-drops-237196},
doi = {10.4230/LIPIcs.CCC.2025.25},
annote = {Keywords: Quantum Error Correction, Quantum LDPC Code, Homological Product, Iterative Construction}
}