Pure states resulting from decoherence in periodic Landau-Zener transitions

Abstract

We consider a two-level (spin) system interacting with a strong, two-color periodic external field that induces a sequence of avoided level crossings. Additionally, the system is embedded in a bosonic reservoir which leads to decoherence and drives the system towards an incoherent sum of periodic Floquet states independently from the initial state. We found that the combined effect of decoherence and the series of Landau-Zener-Stuckelberg-type transitions can be the appearance of time-dependent pure states. These pointer states are the long time limit solutions, regardless of the decoherence rate. Possible applications include quantum optical systems, quantum information processing and molecular nanomagnets.