Almost optimal geometrically local quantum LDPC codes in any dimension.

Li, Xingjian; Lin, Ting-Chun; Wills, Adam; Hsieh, Min-Hsiu · Nat Commun · 2026

basic_science · Level V

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Abstract

Geometrically local quantum codes, comprised of qubits and checks embedded in <math xmlns="http://www.w3.org/1998/Math/MathML"> <msup><mrow><mi>R</mi></mrow> <mrow><mi>D</mi></mrow> </msup> </math> with local check operators, have been a subject of significant interest. A key challenge is identifying the optimal code construction that maximizes both code dimension and distance under the geometric constraints. In this work, we introduce a construction that can transform any good quantum LDPC code into an almost optimal geometrically local quantum code. Our approach hinges on a novel yet simple procedure that extracts a two-dimensional structure from an arbitrary three-term chain complex, building a connection between geometric operations and code constructions. We expect that this procedure will find broader applications in areas such as weight reduction and the geometric realization of chain complexes.