Entanglement in two-mode continuous variable open quantum systems

Abstract

Abstract. Entanglement plays a crucial role in quantum information protocols, thus the dynamical behavior of entangled states is of a great importance. In this paper we suggest a useful scheme that permits a direct measure of entanglement in a two-qubit cavity system. It is realized in the cavity-QED technology utilizing atoms as flying qubits. To quantify entanglement we use the concurrence. We derive the conditions, which assure that the state remains entangled in spite of the interaction with the reservoir. The phenomenon of sudden death entanglement (ESD) in a bipartite system subjected to squeezed vacuum reservoir is examined. We show that the sudden death time of the entangled states depends on the initial preparation of the entangled state and the parameters of the squeezed vacuum reservoir.

Entanglement and discord in two-mode Gaussian open quantum systems

“…Dissipation favorizes the phenomenon of entanglement sudden death -with increasing the dissipation parameter λ, the entanglement suppression happens earlier. The same qualitative behaviour of the time evolution of entanglement was obtained previously [10,11] in the particular case n 1 = 0 and n 2 = 0 corresponding to an initial two-mode squeezed vacuum state.…”

Quantum correlations of two-mode Gaussian systems in a thermal environment

“…One can also show that the dissipation favors the phenomenon of entanglement sudden death -with increasing the dissipation parameter λ, the entanglement suppression happens earlier. The same qualitative behaviour of the time evolution of entanglement was obtained previously [19,27] in the particular case n 1 = 0 and n 2 = 0 corresponding to an initial two-mode squeezed vacuum state and in the case of symmetric initial squeezed thermal states. Comparing the present results with those obtained in the previous paper [20] one can assert that the asymmetry (a = b) of the initial Gaussian state favors the suppression of entanglement.…”

Coherence Dynamics of Two Interacting Bosonic Modes in a Thermal Environment

“…In order to obtain a realistic description of the quantum processes it is necessary to take decoherence and dissipation into consideration. Recently we studied, in the framework of the theory of open systems, the dynamics of quantum correlations of two, both uncoupled and coupled, bosonic modes embedded in a common thermal bath, for initial Gaussian states of the system [24][25][26][27][28][29][30]. e-mail: isar@theory.nipne.ro…”