Quantum Tunneling Phenomena Of Bose-Einstein Condensate In Double Well

In 1995, three groups in U. S. have realized Bose-Einstein Condensate (BEC) in alkali metal atomic gas (87Rb, 23Na and 7Li) in laboratory, respectively. And now there are many groups in the world doing research on the superfluidity, optical properties, tunneling properties, stable properties, and vortices state of BEC.Josephson Effect between two macroscopic phase-coherent wave functions is a famous phenomenon based on tunneling. This effect has been observed in different systems such as two superconductors separated by a thin insulator and two reservoirs of superfluid helium connected by nanoscopic apertures. There also exists Josephson Effect in coupled BECs, and interaction among tunneling particles plays a determinative role in such systems. This nonlinearity gives rise to a new phenomenon, called macroscopic quantum self-trapping effect.The double well model is a basic and simple physical model, in which the atom interference phenomena and quantum tunnelling phenomena of BEC could be well studied.This thesis carries research on BECs'dynamic properties in asymmetric double well by using the semi-classical theory. The main works of this thesis are as follow: 1. BECs'dynamic properties in asymmetric double well are reviewed with weak interaction and non-periodical potential, following which BECs'dynamic behaviors in the two double wells in zero phase mode,Ï€phase mode and running phase mode, as well as the analysis of these dynamic behaviors, are stated.2. The BECs'dynamic properties in asymmetric double well with weak interaction and non-periodical potential are described by using mean-field and two-mode approximation theory. And how BECs'dynamic behaviors change with the variation of ground state energy difference between two double wells in zero phase mode,Ï€phase mode and running phase mode. At last, these dynamic behaviors are analyzed.