= Quantum error-correcting code
{title2=$\mathcal C\subseteq(\mathbb C^2)^{\otimes n}$}
= Quantum code
{synonym}
A quantum error-correcting code is a subspace encoding a logical <Hilbert space>, together with a specified family of noise operators that a common recovery <quantum channel> reverses on every encoded state. A K-dimensional code carries $\log_2K$ logical qubits. For a code projector $P$, correctability is characterized by the <Knill--Laflamme condition>; code distance is defined by the smallest undetectable operator weight, not merely by the number of generators.
Back to article page
