Distinguishing quantum states using time travelling qubits in a presence of thermal environments

摘要

We consider quantum circuits with time travel designed for distinguishingspecific nonorthogonal quantum states in two most popular models: Deutschs andpostselected. We modify them by a presence of weakly coupled thermalenvironment. Using the Davies approximation we study how the thermal noiseaffects an ability of the circuits to distinguish nonorthogonal quantum states.We show that for purely dephasing environment a paradoxial power of suchcircuits remains preserved. We also present a physics based argument forconditions of validity of the maximum entropy rule introduced by David Deutschfor resolving the uniqueness ambiguity in a circuit with time travel.