The Effects On Tunneling Dynamics Of The Fermi Superfluid Gases By Manipulating The Scattering Length

The achievement of Bose-Einstein Condensation in dilute alkali gases stimulates peo-ple’s research interest in the field of ultracold atoms.Recently,studies on the ultracoldfermi gas attract vast focus and interest. It is well known that the particles in the ma-terial world can be divided into Bosons and fermions.Where bosons spin for integertimes, and fermion spin as half integer times, But the Paired Fermions can show thecharacteristics of Bosons At the same time in a diferent state of fermion collisions of Swaves can also use Feshbach Resonance technology change the interaction between atomsin diferent states.Firstly, this thesis Presents the introduction to the research background of atomicBose-Einstein Condensation. The experiment of magnetic Feshbach resonance technologyand the tunneling theory is discussed. A double-well system is an important model tostudy quantum tunneling.In chapter2,introduced the research progress of ultracold Fermigases.Under the mean-field approximation theory,using two mode approximation In BECsystem deduced the dynamics equation for Fermi superfluid gas. It can be cast intothe canonical transformation§and got the classical Hamiltonian of the Fermi superfluidgases. Using4to5order Runge-kutta method to solve dynamic equation numerically.we have investigated tunneling dynamics of superfluid Fermi gas in a double-well poten-tial by adjusting the scattering length which may be varied from large negative to largepositive values by using the Feshbach resonance technique. The double-well can be cre-ated, for example, by superimposing a blue-detuned laser beam upon the center of themagnetic trap. In this case, γ denotes the diference of the zero-point energy betweentwo wells.The barrier height (k) can be efectively controlled by adjusting the intensityof the blue-detuned laser beam. Initially, we upload superfluid fermions pairs into onewell, then adjusting the scattering length or y by Feshbach resonance technique and downthe transition should be observed.We find that the scattering length ascand the energybias γ could afect the quantum transition dramatically. At certain regime,the completepopulation transfer between two modes can be obtained. However, at other regimes, thequantum transition can be completely blocked.In chapter3,we investigate the tunneling dynamics of the Fermi superfluid gases ina double-well potential in a unitarity regime by manipulating the Fermi-Fermi scatter-ing length.Combined with the properties of Fermi superfluid gases,we find the scatteringlength can afect the quantum transition dramatically.The scattering length asccan beadjusted flexibly by Feshbach resonance. Initially, we upload superfluid fermions pairsinto one well, then adjusting the scattering length or y by Feshbach resonance technique and down the transition should be observed or not.Finally, the comparison between theanalytical and the numerical results shows a good agreement. In such a system, the wavefunction can be described by a superposition of two states that localize in each well sep-arately. The double-well can be created, for example, by superimposing a blue-detunedlaser beam upon the center of the magnetic trap. In this case, γ denotes the diference ofthe zero-point energy between two wells. The scattering length asccan be adjusted flexiblyby Feshbach resonance.The barrier height (k) can be efectively controlled by adjustingthe intensity of the blue-detuned laser beam. The results tell us that the scattering lengthascof the dimensionless interaction parameter y plays an important role in the quantumtransition probabilities. It suggests that quantum transition of the superfluid fermi gasfrom one well to the other can be controlled by Feshbach resonance.In Chapter4,the whole thesis is summarized,an outlook of the future study is given.