Modulation instability of two-dimensional Bose-Einstein condensates with helicoidal and a mixture of Rashba-Dresselhaus spin-orbit couplings

Abstract

The modulational instability (MI) process is exclusively studied in a two-component Bose-Einstein condensate (BEC) which includes Rashba-Dresselhaus (RD) spin-orbit (SO) and helicoidal SO couplings. A generalized set of two-dimensional (2D) Gross-Pitaevskii (GP) equations is derived. The tunability of the helicoidal gauge potential is exploited to address BECs dynamics in a square lattice. The MI growth rate is derived, and parametric analyses of MI show the dependence of the instability on interatomic interaction strengths, the RD SO coupling, and helicoidal SO coupling, which combines the gauge amplitude and the helicoidal gauge potential. Direct numerical simulations are carried out to confirm the analytical predictions. Trains of solitons are obtained, and their behaviors are debated when the RD SO parameters are varied under different combinations between the gauge amplitude and the helicoidal gauge potential. The latter gives a potential way to manipulate the trapping capacities of the proposed BEC model.