Particle And Spin Transports Of Spin-Orbit Coupled Fermi Gases Through A Quantum Point Contact

In recent years,the study of non-equilibrium behavior in cold atomic systems has gradually become a hot spot.Due to the high degree of cleanliness and controllability of cold atoms,physicists can realize the study of many transport behaviors in cold atom systems that cannot be achieved in material physics.In chapter 1,we introduce the relevant experimental progress in cold atom transport.At first,a two-dimensional transport channel was built.On this basis,particle transport and thermal transport were studied.With the improvement of experimental technology,two-dimensional transport channels become one-dimensional quantum point contact.The experimental results of the quantum point contact show that the conductance demonstrate the structure of plateau,but it is worth noting that there is an interesting phenomenon called "0.7 anomaly",and its microscopic origin has been in a state of debate.In addition,spin-orbit coupling is also a hot topic in research.Therefore,combining the two,this thesis has two starting points,one is to consider whether the "0.7 anomaly" phenomenon will appear when we consider the spin-orbit coupling in the particle transport,and another is to analyze how our system excites spin current.The second part of this thesis presents the transport behavior of normal Fermi gases through quantum point contact.Firstly,the experimental framework of quantum point contact is briefly introduced,and then the basic concept of quantum point contact is introduced.We then review the experimental results from a theoretical point of view,Finally,our result is consistent with the experimental results.We show that in the noninteracting Fermi system,the change of conductance with the gate voltage demonstrate the structure of plateau.This phenomenon that makes the quantum properties of matter apparent.It provides important insights into mesoscopic physics.The result well described by the Landauer-Büttiker formula.The third part of the thesis investigates the particle and spin transport through a quantum point contact between two Fermi gases with Raman-induced spin-orbit coupling are investigated.We show that the particle and spin conductances both demonstrate the structure of plateau due to the mesoscopic scale of the quantum point contact.Compared with the normal Fermi gases the height of the plateau of the particle conductance is enhanced by the spin-orbit coupling effect for the whole parameter space.This implies that the "0.7 anomaly" observed in mesoscopic experiments is unlikely induced purely by the spin-orbit coupling.Furthermore,the generation of spin current is investigated in this system.We find that the spin current can only be induced by the bias of spin difference between the two reservoirs for the case of vanishing two-photon detuning.When the two-photon detuning is non-zero,the spin current can also be generated by the bias of total particle number between the two reservoirs.It could have potential applications in information storage and computing.