C. Benedetti, F. Buscemi, P. Bordone, M. G. A. Paris
We address the dynamics of entanglement and quantum discord for two non interacting qubits initially prepared in a maximally entangled state and then subjected to a classical colored noise, i.e. coupled with an external environment characterized by a noise spectrum of the form 1/f^a. More specifically, we investigate the dynamics for two different configurations of the environment: in the first case the noise spectrum is due to the interaction of each qubit with a single bistable fluctuator with an undetermined switching rate, whereas in the second case we consider a collection of classical fluctuators with fixed switching rates. Since environmental noise is introduced by means of stochastic time-dependent terms in the Hamiltonian, we are able to describe the effects of both separate and common environments. The full quantum dynamics of the system is obtained by averaging over different noise parameters. We show that environments with the same power spectrum, but different configurations, give raise to opposite behavior for the quantum correlations. In particular, depending on the characteristics of the environmental noise considered, both entanglement and discord display either a monotonic decay or the phenomena of sudden death and revivals. Our results show that the microscopic structure of environment, besides its noise spectrum, is relevant for the dynamics of quantum correlations, and may be a valid starting point for the engineering of colored environments.
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http://arxiv.org/abs/1212.1484
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