QUANTUM INVESTIGATION OF LASER COOLING AND TRAPPING OF POLARITON AND POLARON IN NANOSTRUCTURES

Résumé

Nowadays, exciton polaritons that arise through the strong coupling between excitons and photons are major candidates to demonstrate a wide array of fundamental phenomena and potential applications that range from Bose-Einstein-like condenstation to analogue Hamiltonian simulators and chip-scale interferometers. In the present thesis, we investigate the effect of surrounding environment on the dynamic of laser cooled and trapped polariton and polaron in nanostructures. We consider the system of interest as a TLS with ground state g and first excited state e . We begin our analysis studying the dynamical behavior of a system of laser cooled and trapped polariton within semi-classical approach. Later, we introduce a magnetic field which we consider as a trap and perform the Vonn Neumann entropy. We found that the probability of finding cooled and trapped polariton in the excited state and energy of the system is controlled by the surrounding environment. Based on the matrix representation of the system’s Hamiltonian, we identified and formulated the Landau Zener problem in cooling and trapping of polariton. Motivated by the fact that (i) polaron can be considered as TLS, (2i) polaron are fermions which satisfied the Fermi-Dirac statistics and (3i) polaritons became intermediate particles due to laser cooling and trapping process thereby satisfying Fermi-Dirac statistics althougth they are bosons, we extended our study to polaron. Due to their physical properties, we found interesting the use of two dimensional (2D) transition metal dichalcogenides (TMDs) materials of MX2 types as new playground for laser cooling and trapping of polariton as well as polaron. Using Landau-Zener-Stückelberg Interferometry theory (LZSIT) in one hand and both the quantum mechanical Schrödinger approach (QMSA) and the improved wigner-Brillouin theory (IWBT) on the other hand, we investigated Landau energy levels (LELs) and transition probabilities in both diabatic and adiabatic basis of the laser cooled and trapped polariton and polaron. We showed that the effect of surrounding environment on the dynamic of laser cooled and trapped polariton and polaron is considerably reduced in 2D TMDs materials of our choice as compared to that of nanostructures. In addition, laser cooling and trapping phenomenon is highly appreciated in 2D TMDs material MoSe2 which stands therefore as appropriate candidate for quantum implementation and simulation nanodevices.

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