Theoretical Study Of Atom Optics Elements Based On Spin-orbit Coupling

In the quantum world,the distinction between particles and waves loses much of its significance.de Broglie proposed that all massive particles should be thought of as waves.In ultracold atoms,de Broglie wavelength could be longer,which make particles have fluctuation properties.The experimental realization of ultracold atoms opens the door of atom optics.We can study fluctuation properties in ultracold atoms,such as diffraction and interference.The experimental elements used to study atom optics are called atom optics elements,such as atom lens,atom mirror and atom splitter.Atom optics elements play an important role in atomic and molecular physics,quantum optics,quantum information and precise measurement.Atom interferometer is the central atom optics device,which plays a significant role in precise measurement,navigation and geology.Atom mirror and splitter are key elements in atom interferometer.We will study about these two atom optics elements.Spin-orbit(SO)coupling is the coupling between particle's spin and momentum,which plays an important role in spintronics.We can manipulate spin of a system through non-magnetic methods based on spin-orbit coupling.Because the spin-orbit interaction in materials is difficult to change,we could study spin-orbit coupling in ultracold atoms.We build quantum scattering models of ultracold atoms with spin-orbit interaction to design spin-sensitive atom optics elements,which combine atom optics with spintronics.In our work,we propose a spin-sensitive atom mirror via spin-orbit coupling.We consider a matter wave packet of ultracold-atom gas impinging upon a step potential created by the optical light field,inside of which the atoms are subject to spin-orbit interaction.We study different scattering processes in the potential and discuss the dependence of reflectivity and spin polarization on the incident angle,incident energy and the strength of spin-orbit coupling.We show that the proposed system can act asan effective spin polarizer or spin-selective atom mirror.The spin-dependent scattering properties inherent in this system can find applications in the spin-dependent atom interferometer and quantum measurement.We study the spin splitter of Dirac-Weyl fermions.Based on the quantum simulation of multicomponent ultracold atoms in a two-dimensional square optical lattice,we find that laser-assisted spin-dependent hopping leads to low-energy excitations related to Dirac-Weyl fermions with arbitrary spin.We design an effective beam splitter for Dirac-Weyl fermions through the Goos-H?nchen shift.It is implemented via the birefringence of a wave packet of spin-3/2 Dirac-Weyl fermions impinging upon a potential barrier.We study the dependence of Goos-H?nchen shift and the transmission probability on the incident angle,the height and the width of the potential barrier.The proposed matter wave beam splitter of Dirac-Weyl fermions can find useful applications in spin-relevant devices such as spin-dependent interferometer.We will study the atomic one-way spin switch of the SO coupled ultracold atom subject to a moving spin-independent rectangular potential barrier.Due to that SO breaks Galilean invariance,the spin orientation of the atom can be switched unidirectionally and thus can serve as a one-way spin switch.Different atomic scattering processes are analyzed at different barrier velocity.We explore the spin polarization rate and transmission coefficient in a wide range of barrier velocity.We find that the spin switch can reach an efficiency close to 1 at appropriate parameters.We also discuss the dependence of transmission probability and spin polarization on the barrier's height and width.This study presents a comprehensive understanding of the physical mechanism underlying the system's function as a spintronic device and plays an important role in next-generation one-way spintronic devices and quantum devices.