Quantum code for quantum error characterization

A quantum error-correcting code is a subspace $\mathcal{C}$ such that allowed errors acting on any state in $\mathcal{C}$ can be corrected. A quantum code for which state recovery is only required up to a logical rotation within $\mathcal{C}$ can be used for the detection of errors, but not for quantum error correction. Such a code with a stabilizer structure, which we call an ``ambiguous stabilizer code'' (ASC), can nevertheless be useful for the characterization of quantum dynamics (CQD). The use of ASCs can help lower the size of CQD probe states used, but at the cost of an increased number of operations.