CSS construction: dual classical codes C_1 ⊃ C_2^⊥ → stabilizer code correcting X + Z errors separately

Calderbank-Shor-Steane 1996 construction. Start from two classical binary linear codes C_1 ⊃ C_2^⊥ (i.e. every codeword of C_2^⊥ is also a codeword of C_1). Stabiliser group is generated by X-type generators built from parity checks of…