Spin-orbit-coupled spinor gap solitons in Bose-Einstein condensates

TL;DR

This paper investigates the properties of spin-orbit-coupled spinor gap solitons in Bose-Einstein condensates with optical lattices, revealing two families of solitons and symmetry-breaking phenomena relevant to experimental systems.

Contribution

It introduces a new classification of gap solitons based on spin-dependent parity and demonstrates their physical origin using an approximate model.

Findings

Two families of spinor gap solitons with opposite parity identified.

A model replacing the optical lattice with a harmonic trap explains soliton origins.

Spontaneous parity symmetry breaking occurs at large negative quadratic Zeeman shifts.

Abstract

Spin-1 spin-orbit-coupled spinor Bose-Einstein condensates have been realized in experiment. We study spin-orbit-coupled spinor gap solitons in this experimentally realizable system with an optical lattice. The spin-dependent parity symmetry of the spin-orbit coupling plays an important role in properties of gap solitons. Two families of solitons with opposite spin-dependent parity are found. Using an approximating model by replacing the optical lattice with a Harmonic trap, we demonstrate the physical origination of these two families. For a large negative quadratic Zeeman shift, we also find a type of gap solitons that spontaneously breaks the spin-dependent parity symmetry due to the ferromagnetic spinor interactions.