Ground states and dynamics of spin-orbit-coupled Bose-Einstein condensates

TL;DR

This paper provides a comprehensive analysis of the ground states and dynamics of spin-orbit-coupled Bose-Einstein condensates, revealing complex behaviors due to SO and Raman couplings through analytical, asymptotic, and numerical methods.

Contribution

It establishes existence and non-existence results for ground states, analyzes their structures, and develops efficient numerical methods for simulating dynamics in SO-coupled BECs.

Findings

Ground state structures depend on SO and Raman coupling strengths.

Center-of-mass motion can be non-periodic or frequency-shifted.

Numerical methods accurately capture rich phenomena in SO-coupled BECs.

Abstract

We study analytically and asymptotically as well as numerically ground states and dynamics of two-component spin-orbit-coupled Bose-Einstein condensates (BECs) modeled by the coupled Gross-Pitaevskii equations (CGPEs). In fact, due to the appearance of the spin-orbit (SO) coupling in the two-component BEC with a Raman coupling, the ground state structures and dynamical properties become very rich and complicated. For the ground states, we establish the existence and non-existence results under different parameter regimes, and obtain their limiting behaviors and/or structures with different combinations of the SO and Raman coupling strengths. For the dynamics, we show that the motion of the center-of-mass is either non-periodic or with different frequency to the trapping frequency when the external trapping potential is taken as harmonic and the initial data is chosen as a stationary state (e.g. ground state) with a shift, which is completely different from the case of a two-component BEC without the SO coupling, and obtain the semiclassical limit of the CGPEs in the linear case via the Wigner transform method. Efficient and accurate numerical methods are proposed for computing the ground states and dynamics, especially for the case of box potentials. Numerical results are reported to demonstrate the efficiency and accuracy of the numerical methods and show the rich phenomenon in the SO-coupled BECs.