Quasi-Orthogonal Stabilizer Design for Efficient Quantum Error Suppression

Abstract: Orthogonal geometric constructions are the basis of many many quantum error-correcting codes (QEC), but strict orthogonality constraints limit design flexibility and resource efficiency. We introduce a quasi-orthogonal geometric framework for stabilizer codes that relaxes these constraints while preserving the symplectic commutation structure on the binary symplectic space $\mathbb{F}_{2}^{2}$. The approach permits controlled overlap between X- and Z-check supports, leading to quasi-orthogonal Pauli operators and a generalized notion of effective distance defined via induced anti-commutation with logical operators. This relaxation expands the stabilizer design space, enabling codes that approach the Gilbert-Varshamov regime with improved logical rates at moderate distances. Finite-length constructions, including quasi-orthogonal variants of the $[[8,3,\approx 3]]$, $[[10,4,\approx 3]]$, $[[13,1,5]]$, and $[[29,1,11]]$ codes, demonstrate consistent improvements over strictly orthogonal counterparts. Under depolarizing noise with error rates up to $p=0.30$, logical error rates, fidelities, and trace distances improve by up to two orders of magnitude. These improvements reflect the increased connectivity of the underlying stabilizer geometry while remaining compatible with standard decoding schemes. The proposed framework offers a principled extension of stabilizer code design through quasi-orthogonal geometric structures.