Dependence of decoherence and quantum measurement process on the number of environmental dynamical variables

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 beexploited 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. However, it has at least two key features: i) it is a dynamical process and ii) it is due to the interaction with an environment, which set the topic into the domain of the open quantum systems (OQS) dynamics. In this work, we make use of a recently proposed method[1] for studying OQS, in order to analyze 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 extending the coherence time which also enlighten the relation between decoherence and the quantum measurement process.References[1] Calvani, D., Cuccoli, A., Gidopoulos, N.I., and Verrucchi, P. (2013), Parametric representation of open quantum systems and cross-over from quantum to classical environment, Proceedings of theNational Academy of Sciences 110, 6748-6753.