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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 17:50 |
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Conference: Bucharest University Faculty of Physics 2014 Meeting
Section: Theoretical Physics and Applied Mathematics
Title:
Quantum correlations in quantum information theory
Authors:
A. ISAR
Affiliation:
Department of Theoretical Physics, National Institute of Physics and Nuclear Engineering, Bucharest-Magurele
E-mail
isar@theory.nipne.ro
Keywords:
Quantum correlations, quantum entanglement, quantum discord, open quantum systems
Abstract:
We discuss the role of quantum correlations (quantum entanglement and quantum discord) in the theory of quantum information and in the applications of processing and transmission of quantum information. In particular, in the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we analyze the possibility of entanglement generation in a system consisting of two interacting bosonic modes embedded in a common thermal environment. By taking an initial separable squeezed thermal state, we show that entanglement generation may take place, for definite values of the parameters characterizing the initial state of the system (squeezing parameter, average photon numbers), the coefficients describing the interaction of the system with the reservoir (temperature, dissipation constant) and of the strength of interaction between the two modes. After its generation one can observe temporary suppressions and revivals of the entanglement. In the case of an initial entangled squeezed thermal state, entanglement suppression (entanglement sudden death) takes place for all temperatures of the thermal bath. Like in the case of an initial separable state, one can observe temporary revivals and suppressions of entanglement. In the limit of large times the system evolves asymptotically to an equilibrium state which can be entangled or separable. The direct interaction between the two modes favors the generation or the preservation of the created entanglement, while the temperature of the thermal bath acts towards preventing the generation of entanglement or suppressing it once it was created. It is the competition between these two factors which determines the final state of being separable or entangled.
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