Fig. 3: Pseudo-threshold crossover for recovery using the [[5, 1, 3]] code.
The model examines the impact of errors under an uncorrelated depolarizing channel showing a p ≈ 0.50 pseudo threshold for the full correction procedure. We plot the logical infidelity 1 −;FL where FL is the logical fidelity of a selected state in the code space of the [[5, 1, 3]] code as a function of the depolarizing probability for each qubit p. The label l denotes the number of products from the stabilizer generators used in the expansion operator set. The physical line depicts the same error if the logical state is encoded in a single qubit in the standard way. The “bare'' line indicates the logical error rate with no recovery procedure applied. The starred lines close to each level of the hierarchy show an approximation to that level of projection using the QSE projection with 2 less check operators to demonstrate the smooth performance of the subspace procedure.
