Short random circuits define good quantum error correcting codes

We study the encoding complexity for quantum error correcting codes with large rate and distance. We prove that random Clifford circuits with O(nlog² n) gates can be used to encode k qubits in n qubits with a distance d provided k/n <; 1 - d/n log₂ 3-h(d/n). In addition, we prove that such circuits typically have a depth of O(log³ n).