Quantum environment for a longer coherence time

Decoherence is one of the main obstacles placed in the way of the correct functioning of quantum devices. It is an ubiquitous phenomenon, due to the unavoidable interaction between a quantum principal system and its environment, which becomes particularly disruptive when quantum properties are to be exploited and controlled. Despite being an ordinary effect, decoherence is not easily describable in a general framework, as it depends on several details of the physical setup. In this work, we make use of a recently proposed method [1] for studying the dynamical evolution of a generic quantum system subject to decoherence. From such treatment, an analytical expression for a consistent measure of the coherence time, emerges, and formally shows how, and why, decoherence depends on the number of dynamical variables of the environment. Based on this result we propose a strategy for effectively reduce decoherence, and finally implement it in two exemplifying situations where decoherence must be kept under control. [1] D. Calvani, A. Cuccoli, N.I. Gidopoulos, and P. Verrucchi, "Parametric representation of open quantum systems and cross-over from quantum to classical environment", Proceedings of the National Academy of Sciences 110 , 6748- 6753.