Update(06.08.14): Below are the slides from Rosario’s talk. He presented many results and posed some nice questions. Thanks Rosario!
As I mentioned in a previous post, the first week of August (04-08) there will many quantum-info guests here at qig@CBPF. We basically have a self organized small conference thing going on. Just to have some sort of structure, we asked Rosario to give a talk on his latest results about dynamics of quantum correlations. See the details below. If you are willing to experience the quantum-info gathering next week at CBPF, just pop up here!
Speaker: Rosario Lo Franco (University of Nottingham)
Title: On the theoretical and experimental dynamics of quantum correlation resources in independent environments
Coordinates: room 601D, CBPF. 06.08, 16:00h
Abstract: Quantum correlations (entanglement, discord, nonlocality) in composite quantum systems are essential resources for quantum information processing [1, 2]. The exploitation of these quantum resources is jeopardized by the detrimental effects of the environment surrounding the quantum system. For instance, under Markovian noise they decay asymptotically or disappear at a finite time [2–4]. This drawback leads one to look for conditions where quantum correlations can be recovered and preserved during the evolution. To this aim non-Markovian noise, arising from strong couplings or structured environments, has been shown to be fundamental because of its memory effects. Quantum correlations between qubits in independent non-Markovian environments can exhibit revivals [2, 5, 6] and also freezing under suitable conditions [5, 7, 8], giving extensions of their use. For composite quantum systems within independent quantum environments, revivals of quantum correlations are typically interpreted as due to correlation exchanges induced by the back-action on the systems by their non-Markovian quantum environments [9-12]. Recently, it has been shown that revivals of quantum correlations may also occur when the environment is classical, thus unable to store quantum correlations, and forbids system-environment back-action [13-19]. This fact leads to basic issues on the interpretation of this phenomenon, in particular about the role of: (i) classical environments in reviving quantum correlations; (ii) collective effects of the environment on the qubits; (iii) memory effects; (iv) possible system-environment correlations.
In this lecture I present an overview of some theoretical and experimental results about the dynamics of quantum correlations in independent environments, particularly under non-Markovian conditions. I then focus on the case of classical environments and describe a model suitable to address this issue . I report the results of an all-optical experiment that simulates this model and allows us to observe and control revivals of quantum correlations without system-environment back-action . Finally, I discuss about non-Markovianity and provide a possible interpretation showing the role of the classical environment in this phenomenon. The findings so far tell us that revivals of quantum correlations are a dynamical feature of composite open systems irrespective of the nature, classical or quantum, of the environment.
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