Study On Quantum Vortex Phenomenon Of Many Sub-BECs Formed By Expansion And Superposition

An analysis is presented of the phase vortices formed by superposition of multiple Bose condensed gases in different types of potential wells in the two dimensional case.The essence of the vortex formed is that the spiral of the phase is changed.The different regions of Bose gas could be represented by the vector of phase space.If the phase vectors are superposed closed,there will be a vortex.This paper focuses on this principle that uses a series of two dimensional bose condensed gas as the material wave,and the calculation and research are analyzed by gauss approximation.The results are as follows.On the basis of two-dimensional "discs-shaped" bose condensation gas,by using the three-group symmetric distribution of the Bose condensed gas are produced by the laser potential well,and the initial wave function of the condensed gas could be approximately regarded as a Gaussian wave packet.The three groups of Bose condensed gas were expanded under various potential wells(like free space or harmonic trap,etc.)without considering the interaction of particles.The formation mechanism of quantum vortex by the expansion and superposition of the many sub-BECs is studied.by using the propagation method,The physical processes of the macroscopic quantum vortex formed by the symmetric distribution of the three sub-BEC expansion and superposition are analyzed,and the law of quantum vortex with time evolution is obtained;It is found that the vortex distribution is oscillating in the harmonic trap,and vortex and anti-vortex are mutually transformed in time.Those phenomena also be analyzed in this paper.