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arXiv:1611.07063

Temperature dependent quantum correlations in three dipolar coupled two-level atoms

Shaik Liyakhath Ahmed

Published Nov 18, 2016• 0 citations
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Abstract

We investigate the thermal entanglement characteristics of three dipole-coupled two-level atoms arranged in two different configurations - in a line with nearest neighbour coupling and in a closed loop with each atom interacting with both its neighbours. It is observed that in loop configuration, any one of the three atoms is indeed entangled with the other two atoms in the system, which are not mutually entangled, and further that this feature is specific to only the loop configuration, which is markedly absent in the line configuration. A detailed study of the quantum correlations demonstrated how these can be tuned by varying the temperature and the dipole dipole coupling strength, in both the configurations.

DOI
10.48550/arxiv.1611.07063

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We investigate the super and sub-radiance characteristics of the radiation emitted from a system of three two-level atoms, in the GHZ and W-states. The dipolar coupling between atoms leads to two distinct configurations, one in which the three atoms are on a line, and the other in a closed loop form, wherein each atom interacts with both its neighbours. The quantum statistical properties of the emitted radiation show distinctly different characteristics for the GHZ and W-states resulting from the above configurations. The far-field radiation pattern also shows distinct differences between differently entangled states, making it possible for optical probing of entangled states.
We present analysis of a system of three two-level atoms interacting with each other through the dipole-dipole interaction. The interaction manifests between excited state of one of the atoms and the ground state of its nearest neighbour. Steady state populations of the density matrix elements are presented and are compared with a situation when only two atoms are present. It can be noticed that the third atom modifies the behaviour of the three atoms. Two configurations are analysed, one in which the three atoms are in a line, with no interaction between atoms at the end points and the other in which the atoms form a closed loop with each atom interacting with both its neighbours.
We demonstrate that light quanta of well defined characteristics can be generated in a coupled two-level system of three atoms. The quantum nature of light is controlled by the entanglement structure, discord, and monogamy of the system which leads to sub and superradiant behavior as well as sub-Poissonian statistics, at lower temperatures. Two distinct phases with different entanglement characteristics are observed with uniform radiation in one case and the other displaying highly focused and anisotropic radiation in far field regime. At higher temperatures, sub and superradiant light is found to persist in the absence of entanglement but with non-zero quantum discord, showing bunching of photons. It is shown that the radiation intensity can be a precise estimator of the inter-atomic distance of coupled two-level atomic systems. Our investigation shows for the first time, the three body correlation in the form of `monogamy score' controlling sub and superradiant nature of radiation intensity.
A new mechanism of development of quantum correlations due to the combined effects of a common heat bath and a resonant classical electromagnetic field is analyzed for a system of two two-level atoms coupled by dipole-dipole interaction. Conditions are found under which arbitrary steady-state entanglement can be created in the absence of measurement in an entangled basis. The analysis of dynamics of entanglement is focused on the effects of dipole-dipole interaction, mean number of thermal photons, degree of squeezing of thermal radiation, classical field strength, and presence of additional decay channels.