UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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2024-11-23 17:49
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Conference: Bucharest University Faculty of Physics 2016 Meeting


Section: Theoretical Physics and Applied Mathematics


Title:
Quantum Coherence of two-mode systems in a thermal environment


Authors:
S. SUCIU (1,2), A. ISAR (2)


Affiliation:
1) Faculty of Physics, University of Bucharest

2) IFIN-HH


E-mail
serbansuciu2@gmail.com


Keywords:
Quantum Information Theory, Quantum Coherence, Open Systems, Gaussian States


Abstract:
Coherence plays a central role in physics and is a necessary condition for quantum correlations such as entanglement and discord. Recently, a framework for the quantification of coherence has been established, in which quantum coherence is considered to be a resource in a manner similar to quantum entanglement[1]. The main results so far apply mostly to the finite dimensional setting and do not describe many physical relevant situations. For example, quantum optics requires quantum states in infinite dimensional systems, mainly Gaussian states. In the framework of the theory of open systems based on completely positive quantum dynamical semigroups[2][3], we address the quantification of coherence for Gaussian states of continuous variable systems from a geometric perspective. By tracing the distance between our state and the closest incoherent Gaussian state, we calculate the evolution in time of the coherence under the influence of the thermal bath. For this purpose we take as a choice of distance the relative entropy of coherence, as it provides an easy to compute measure. We give a description of the quantum coherence for a system consisting of two non-interacting non-resonant bosonic modes embedded in a thermal environment. For convenience, we take as initial state of the system a two-mode squeezed thermal state, however this form is not preserved in time, therefore the results are valid for all Gaussian states. We find that the quantum coherence drops asymptotically to zero in time under the influence of the thermal bath.


References:

[1] T. Baumgratz, M. Cramer, M. Plenio, PRL 113, 140401 (2014)

[2] G. Lindblad, Commun. Math. Phys. 48, 119 (1976)

[3] V. Gorini, A. Kossakowski, G. Sudarshan, J. Math. Phys. 17, 821 (1976)