Quantum Singleton bound: k ≤ n − 2(d−1); rate ratio R = k/n ≤ 1 − 2(d−1)/n

Quantum Singleton bound (Knill-Laflamme 1997). Setup: an [[n,k,d]] stabiliser code. Theorem: the parameters satisfy k ≤ n − 2·(d−1), equivalently the rate R = k/n ≤ 1 − 2(d−1)/n. Proof via framework F8: the symplectic-rank argument on the…