Decoherence in quantum mechanics

We study decoherence in a simple quantum mechanical model using two approaches. Firstly, we follow the conventional approach to decoherence where one is interested in solving the reduced density matrix from the perturbative master equation. Secondly, we consider our novel correlator approach to decoherence where entropy is generated by neglecting observationally inaccessible correlators. We show that both methods can accurately predict decoherence time scales. However, the perturbative master equation generically suffers from instabilities which prevents us to reliably calculate the system’s total entropy increase. We also discuss the relevance of the results in our quantum mechanical model for interacting field theories.

Research highlights► We study decoherence in a simple quantum mechanical model using two approaches. ► Following the conventional approach to decoherence we solve the master equation. ► We also consider our novel correlator approach to decoherence. ► The system’s total entropy increase cannot reliably be calculated in the conventional approach. ► This does follow correctly from our correlator approach.