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The destabilizer construction moved into QuditCode.get_destabilizer_ops was only correct over GF(2): - The logical/gauge projection relied on a GF(2)-specific sign trick. Replace it with a field-general projection using the inverse of the symplectic form. - The commute-fixing loop subtracted a stabilizer with a hardcoded coefficient; scale by the symplectic overlap (and fix its sign) so it cancels over GF(q). Also fix a cache-rebinding inconsistency: evaluating self.dimension / self.gauge_dimension canonicalizes (and rebinds) the cached stabilizer operators, so both get_destabilizer_ops and get_encoding_tableau now compute the stabilizer count before grabbing stab_ops, keeping the destabilizers dual to the stabilizers actually reported by get_stabilizer_ops. Add destabilizer property assertions to test_qudit_ops (100% coverage of get_destabilizer_ops over GF(2)/GF(3)/GF(4)) and an encoding test exercising the overcomplete-stabilizer fallback. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
QuditCode.dimension and .gauge_dimension counted stabilizer generators via get_stabilizer_ops(canonicalized=True), which rebinds the cached stabilizer operators as a side effect. Count the independent generators with get_stabilizer_ops().row_space() instead, which operates on a copy and leaves the cache intact. With the rebind gone, get_destabilizer_ops and get_encoding_tableau no longer need to evaluate the stabilizer count before grabbing stab_ops, so restore the natural inline condition in both. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
… form The logical and gauge operators are already in standard symplectic form, so their symplectic dual basis is just the operators reindexed as [Z; -X]. Use that directly instead of constructing ops @ symplectic_conjugate(ops).T and inverting it. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Example usage: I have a syndrome vector
syndrome_bits = (s_0, s_1, ...)from stabilizer measurements. I want the destabilizer that zeros out that syndrome and commutes with all logical operators. Say the code is self-dual and defined by a minimal set of stabilizer generators. I can construct the desired stabilizer with some thing like: