Dynamics of classical-quantum correlations between two movable mirrors in optomechanics

2020 ◽  
Vol 34 (08) ◽  
pp. 2050066 ◽  
Author(s):  
M. Amazioug ◽  
L. Jebli ◽  
M. Nassik ◽  
N. Habiballah
Keyword(s):  
Thermal State ◽  
Quantum Correlations ◽  
Strong Coupling Regime ◽  
Squeezed Light ◽  
Fabry Perot ◽  
Classical Quantum ◽  
Rotating Wave ◽  
Quantum Mutual Information ◽  
Down Conversion ◽  
Gaussian Quantum Discord

We study the dynamics of classical-quantum correlations in the nonadiabatic regime, using the rotating wave approximation (RWA), between two movable mirrors of two spatially separated Fabry–Pérot cavities, each of the two cavities having a movable end-mirror and coupled to a two-mode squeezed light from spontaneous parametric down-conversion. This work completes our previous work [M. Amazioug, M. Nassik and N. Habiballah, Eur. Phys. J. D 72, 171 (2018)] where we have studied the transfer of quantum correlations in steady state. The Bures distance is used to quantify the amount of entanglement of the symmetrical squeezed thermal state, and the Gaussian quantum discord is considered to quantify the quantumness of the quantum correlations even though the two movable mirrors are separable. Furthermore, total correlations are quantified using quantum mutual information. Indeed, these three indicators depend mainly on the temperature of the movable mirror and the squeezing parameter in strong coupling regime.

Controlling nonclassical properties of optomechanical systems under the Coulomb interaction effect

2020 ◽  
Vol 18 (08) ◽  
pp. 2150002
Author(s):  
Abderrahim Lakhfif ◽  
Jamal El Qars ◽  
Mostafa Nassik
Keyword(s):  
Coulomb Interaction ◽  
Quantum Coherence ◽  
Quantum Correlations ◽  
Optomechanical System ◽  
Squeezed Light ◽  
Rotating Wave Approximation ◽  
Nonclassical Properties ◽  
Fabry Perot ◽  
Rotating Wave ◽  
Coulomb Effects

In an optomechanical system consisting of two Fabry–Pérot cavities fed by squeezed light and coupled via Coulomb interaction, we respectively use the logarithmic negativity, Gaussian discord and Gaussian coherence to analyze the behavior of three different indicators of nonclassicality, namely the entanglement, quantum discord and quantum coherence. We perform the rotating wave approximation and work in the resolved sideband regime. In two bi-mode states (optical and mechanical), the coherence is generally found to be greater than entanglement and discord. More interestingly, we show that the Coulomb interaction can be used either to degrade or enhance the nonclassical properties of the optical subsystem. In addition, compared with the discord and coherence, the mechanical entanglement is found strongly sensitive to both thermal and Coulomb effects, and it requires a minimum value of cooperativity to be generated. Remarkably, this minimum increases when increasing the Coulomb coupling strength. Finally, we notice that an optimal transfer of quantum correlations between the optical and mechanical subsystems is achieved in the absence of the Coulomb interaction.

Measure of general quantum correlations in optomechanics

2018 ◽  
Vol 16 (05) ◽  
pp. 1850043 ◽  
Author(s):  
M. Amazioug ◽  
M. Nassik ◽  
N. Habiballah
Keyword(s):  
Bath Temperature ◽  
Quantum Correlations ◽  
Atomic Ensemble ◽  
Thermal Bath ◽  
Optomechanical System ◽  
Optomechanical Systems ◽  
Squeezed Light ◽  
Quantum Steering ◽  
Quantum Equations ◽  
Gaussian Quantum Discord

In this paper, we analyze nonclassical correlations between bipartite states in two optomechanical systems. The first system (Sec. 2) consists of two nanoresonators spatially separated by broadband squeezed light, where each cavity has a fixed mirror and a movable one. The second system (Sec. 3) is an atom-optomechanical system consisting of an atomic ensemble placed inside an optical nanoresonator with a vibrating mirror. For both optomechanical systems, we give the Hamiltonian and the explicit expression of covariance matrix leading to the quantum equations describing the dynamic evolution of the system. Then, the nonclassical correlations are quantified using the logarithmic negativity and Gaussian quantum discord. We propose also a scheme for examining the evolution of Gaussian quantum steering and its asymmetry in each system. We show that the entanglement of the two mechanical modes is very strongly related to the parameters characterizing the environment where the movable mirrors evolve, in particular the squeeze parameter, the optomechanical cooperativity and thermal bath temperature.

Dynamic of the Gaussian quantum discord and effect of non-Markovian degree

2015 ◽  
Vol 93 (4) ◽  
pp. 481-485
Author(s):  
Xin Liu ◽  
Wei Wu ◽  
Changkui Hu
Keyword(s):  
Markov Process ◽  
Experimental Method ◽  
Dynamic Characteristic ◽  
Quantum Discord ◽  
Thermal State ◽  
Quantum Correlations ◽  
Continuous Variable ◽  
Zero Temperature ◽  
The Relationship ◽  
Gaussian Quantum Discord

We study the dynamic of the Gaussian quantum discord in a continuous-variable system subject to a common non-Markovian environment with zero-temperature. By considering an initial two-mode Gaussian symmetric squeezed thermal state, we show that Gaussian discord has a very different dynamic characteristic in a non-Markovian evolution versus a Markov process, and can be created by the memory effect, which features non-Markovianity. We also study the relationship between Gaussian discord and the non-Markovian degree of the environment. The results may offer us an effective experimental method to get more quantum correlations.

scholarly journals On Amplification of Light in the Continuous EPR State

2003 ◽  
Vol 01 (02) ◽  
pp. 207-215 ◽  
Author(s):  
V. N. Gorbachev ◽  
A. I. Trubilko
Keyword(s):  
Quantum Correlations ◽  
Continuous Variable ◽  
The Other ◽  
Atomic Ensemble ◽  
Transparent Medium ◽  
Integrals Of Motion ◽  
Squeezed Light ◽  
Type Interaction ◽  
Epr State

Two schemes of amplification of two-mode squeezed light in the continuous variable EPR-state are considered. They are based on the integrals of motion, which allow conserving quantum correlations whereas the power of each mode may increase. One of these schemes involves a three-photon parametric process in a nonlinear transparent medium and the other is a Raman type interaction of light with atomic ensemble. A generalization to multimode squeezed light is discussed.

Dynamics of Interacting Classical and Quantum Systems

2011 ◽  
Vol 18 (04) ◽  
pp. 339-351 ◽  
Author(s):  
Dariusz Chruściński ◽  
Andrzej Kossakowski ◽  
Giuseppe Marmo ◽  
E. C. G. Sudarshan
Keyword(s):  
Characteristic Feature ◽  
Quantum Dynamics ◽  
Quantum Discord ◽  
Main Idea ◽  
Quantum Correlations ◽  
Quantum Systems ◽  
Quantum States ◽  
Algebra Of Observables ◽  
Classical Quantum ◽  
True Quantum

We analyze the dynamics of coupled classical and quantum systems. The main idea is to treat both systems as true quantum ones and impose a family of superselection rules which imply that the corresponding algebra of observables of one subsystem is commutative and hence may be treated as a classical one. Equivalently, one may impose a special symmetry which restricts the algebra of observables to the 'classical' subalgebra. The characteristic feature of classical-quantum dynamics is that it leaves invariant a subspace of classical-quantum states, that is, it does not create quantum correlations as measured by the quantum discord.

scholarly journals QUANTUMNESS OF CORRELATIONS AND ENTANGLEMENT

2011 ◽  
Vol 09 (07n08) ◽  
pp. 1757-1771 ◽  
Author(s):  
A. R. USHA DEVI ◽  
A. K. RAJAGOPAL ◽  
SUDHA
Keyword(s):  
Density Matrix ◽  
General Setting ◽  
Trace Class ◽  
Quantum Correlations ◽  
Completely Positive ◽  
Generalized Measurement ◽  
Linear Maps ◽  
Classical Quantum ◽  
First Time ◽  
General Perspective

Generalized measurement schemes on one part of bipartite states, which would leave the set of all separable states insensitive are explored here to understand quantumness of correlations in a more general perspective. This is done by employing linear maps associated with generalized projective measurements. A generalized measurement corresponds to a quantum operation mapping a density matrix to another density matrix, preserving its positivity, hermiticity, and trace class. The positive operator valued measure (POVM) — employed earlier in the literature to optimize the measures of classical/quantum correlations — correspond to completely positive (CP) maps. The other class, the not completely positive (NCP) maps, are investigated here, in the context of measurements, for the first time. It is shown that such NCP projective maps provide a new clue to the understanding of quantumness of correlations in a general setting. Especially, the separability–classicality dichotomy gets resolved only when both the classes of projective maps (CP and NCP) are incorporated as optimizing measurements. An explicit example of a separable state — exhibiting nonzero quantum discord, when possible optimizing measurements are restricted to POVMs — is reexamined with this extended scheme incorporating NCP projective maps to elucidate the power of this approach.

Thermal geometric discords in a two-qutrit system

2016 ◽  
Vol 14 (03) ◽  
pp. 1650016 ◽  
Author(s):  
Ya-Li Yuan ◽  
Xi-Wen Hou
Keyword(s):  
Magnetic Field ◽  
Quantum Information ◽  
Magnetic Fields ◽  
Weak Magnetic Field ◽  
Quantum Discord ◽  
Quantum Information Processing ◽  
Thermal State ◽  
Quantum Correlations ◽  
High Dimensional ◽  
Lower Temperature

The investigation of quantum discord has mostly focused on two-qubit systems due to the complicated minimization involved in quantum discord for high-dimensional states. In this work, three geometric discords are studied for the thermal state in a two-qutrit system with various couplings, external magnetic fields, and temperatures as well, where the entanglement measured in terms of the generalized negativity is calculated for reference. It is shown that three geometric discords are more robust against temperature and magnetic field than the entanglement negativity. However, all four quantities exhibit a similar behavior at lower temperature and weak magnetic field. Remarkably, three geometric discords at finite temperature reveal the phenomenon of double sudden changes at different magnetic fields while the negativity does not. Moreover, the hierarchy among three discords is discussed. Those adjustable discords with the varied coupling, temperature, and magnetic field are useful for the understanding of quantum correlations in high-dimensional states and quantum information processing.

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