Quantum Transport In Low Dimensional Mesoscopic Fermi And Bose Systems

In this thesis the quantum transport through quantum dot and the atomic quantum dot are investigated by means of the scattering matrix and nonequilibrium Green function techniques.We present a theoretical analysis of thermoelectric transport in the nonlinear regime. The thermopower and thermoconductance in finite temperature gradient are calculated numerically for a double-barrier structure using Landauer-Büttiker like formula. The thermopower is found to oscillate with the chemical potential. Thermopower can either be negative or positive which is well correlated with the behavior of the electric conductance. The thermal conductance is positive de_nite showing that the heat energy is always transferred from hot end to cold end. As the chemical potential is varied, nonlinear thermal conductance exists plateau-like features.With the help of nonequilibrium Green function technique, the electronic transport through series Aharonov-Bohm (AB) interferometers is investigated. We obtain the AB interference pattern of the transition probability characterized by the algebraic sum and difference of two magnetic fluxes and particularly a general rule of AB oscillation period depending on the ratio of integer- quantum-number of fluxes. A parity effect is observed showing the asymmetric AB oscillations with respect to the even and odd quantum-number of total fluxes in antiparallel AB interferometers. It is also shown that the AB fluxes can shift the Fano resonance peaks of the transmission spectrum.We design a quantum transport device—Josephson atomic quantum dot, which is an atomic quantum dot coupled to two Bose-Einstein condensate reservoirs via Raman transition. Our results show that the resonant peak of the transmission probability becomes wide as the Rabi frequency increases, while the quantum tunneling hardly depends on the interaction parameter of the reservoirs because of the strong collisional interactions in the dot. The Josephson current reaches the maximum and appears aπphase shift as Raman detuning approaching the resonant energy. We also extend Josephson atomic quantum dot to superfluid quantum interference devices. How to achieve the parameter region of this quantum device is given in present experimental condition.