Quantum Codes with Transversal $CCZ$ Gates and Sublinear $Z$-Stabilizers

Abstract

We construct quantum CSS codes with transversal \(CCZ\) gates whose \(Z\)-stabilizers admit sublinear-weight generating sets. We build on the algebraic puncturing framework of Guruswami and Golowich \cite{GG24}, which turns classical codes with the required Schur-product and distance conditions into CSS codes with transversal \(CCZ\). However, applying the framework directly to the algebraic expander codes of \cite{KT26} runs into their small dual distance, and therefore produces only sublinear quantum dimension. Our main technical step is a refined puncturing theorem in which the global dual-distance assumption is replaced by a condition only on the selected puncturing set. Applying this theorem to algebraic expander codes gives explicit growing-alphabet CSS codes with parameters \([[N,Θ(N),Ω(N^{1/m})]]\), for every fixed \(m\geq 3\), and with transversal \(CCZ\) gates. Moreover, the \(Z\)-stabilizer space has an explicit generating set of weight \(O(N^{1/m})\). We also reduce the alphabet to a fixed prime field using a projective-multiplicity version of multiplication-friendly codes. The resulting fixed-prime-field CSS code triples, of length \(n\), still have transversal \(CCZ\) gates. Their dimension is near-linear, their distance is \(n^{1/m}\) up to polylogarithmic factors, and the \(Z\)-stabilizer locality remains sublinear, again up to polylogarithmic losses.