Parallel distinguishability of quantum operations

Understand

We find that the perfect distinguishability of two quantum operations by a parallel scheme depends only on an operator subspace generated from their Choi-Kraus operators.

• We further show that any operator subspace can be obtained from two quantum operations in such a way.
• This connection enables us to study the parallel distinguishability of operator subspaces directly without explicitly referring to the underlining quantum operations.
• We obtain a necessary and sufficient condition for the parallel distinguishability of an operator subspace that is either one-dimensional or Hermitian.