Środowiskowe Seminarium z Informacji i Technologii Kwantowych

Unruh effect is usually demonstrated by means of an Unruh-DeWitt detector, which is a point-like quantum system interacting with a quantum field and moving along a path in Minkowski spacetime. The response of a uniformly accelerated Unruh-DeWitt detector is evaluated to leading order in perturbation theory and the detector's excitation rate is found to obey a Planck distribution at the Unruh temperature.We argue that the above treatment has a restricted domain of applicability and we propose that Unruh-DeWitt detectors should be considered as open quantum systems. We calculate the evolution of the detector's reduced density matrix invoking neither the Markov nor the Rotating Wave approximation. Our analysis suggests that the relation between acceleration and temperature is best expressed in terms of the asymptotic state of the detector.