Abstract

We study the behaviors of quantum speed limit time (QSLT) of a two-level atom and non-Markovianity of an atomic ensemble described by the Dicke model. Our results show that both quantities can accurately locate the critical point of quantum phase transition between normal and super-radiant phases of the model. The numerical simulations demonstrate a rapid increase in the non-Markovianity in the super-radiant phase with increasing size of the ensemble. The growing non-Markovianity, in turn, results in speeding up quantum evolution of the two-level atom.

© 2020 Optical Society of America