Optical Quantum Interference Control Of Ultra-cold Atomic Gas

Recently,the development of ultra-cold quantum gases have sparked a rev-olution in atomic physics.Taking advantage of the precise control in quantum systems,quantum gases are now being used to address a range of questions in many-body quantum physics.The Feshbach resonance phenomenon is a hot top-ic in the field of molecular BEC and BCS resonance supercurrent of fermions.Feshbach resonance occurs when the magnetic field is adjusted to coupling the resonance of the scattered states of two free particles to a molecular bound state.The resonant quantum interference of Feshbach controls the scattering length and inhibits inelastic scattering.Research of this paper is intended to analyze and deduce the basic time-dependent scattering formulations in quantum mechanics,and compare it with the time-independent scattering formula.We studied the atomic magnetic~6Li Feshbach resonance scattering.In the process of collision,an incident wave packet approaches the atom instantaneously and distributes to the bound state.When the time approaches to infinity,the Breit-Wigner cross section formula is obtained.Under the Wigner-Weisskopf approximation,it is found that the coupling of discrete and continuous states in the scattering process has the characteristics of contact potential.Our study will provide a theoretical reference for further experimental study of magnetic resonance scattering of~6Li atoms.In this thesis,we also review some basic theories and experiments,and then we discuss the following parts of superradiance.