Collapse and revival of quantum coherence for a harmonic oscillator interacting with a classical fluctuating environment

We address the dynamics of nonclassicality for a quantum system interacting with a noisy fluctuating environment described by a classical stochastic field. As a paradigmatic example, we consider a harmonic oscillator initially prepared in a maximallynonclassical state, e.g. a Fock number state or a Schroedinger cat-like state, and then coupled to either resonant or non-resonant external field. Stochastic modeling allows us to describe the decoherence dynamics without resorting to approximated quantum master equations, and to introduce non- Markovian effects in a controlled way. A detailed comparison among different nonclassicality criteria and a thorough analysis of the decoherence time reveal a rich phenomenology whose main features may be summarized as follows: i) classical memory effects increase the survival time of quantum coherence; ii) a detuning between the natural frequency of the system and the central frequency of the classical field induces revivals of quantum coherence.