Physical Review A
Microphysical irreversibility and the time-reversal operation
Arno Böhm
Abstract
The division of a scattering experiment into the preparation of a state and the registration of an observable in this state defines an obvious but commonly ignored quantum-mechanical arrow of time. This leads to irreversibility on the microphysical level. The time evolution semigroup for exponentially decaying Gamow states is an example of this microphysical irreversibility. A time-reversal operator exists which is compatible with the quantum-mechanical arrow of time.