Quantum retrodiction made fully symmetric

Understand

Quantum retrodiction is a time-symmetric approach to quantum mechanics with applications in a number of important problems.

• One of the major challenges to its more widespread applicability is the restriction of its symmetric formalism to unbiased sources.
• The main result of this paper is to develop a general theory yielding a symmetric formalism for arbitrary sources.
• We then highlight on a specific example, by presenting the optimal solution to the retrodiction problem that is dual to unambiguous state discrimination, how the generalized approach works.