Ground State Phases and Topological Excitations of Spin-1 Bose-Einstein Condensate in Twisted Optical Lattices

TL;DR

This paper explores the ground states and topological excitations of spin-1 Bose-Einstein condensates in a novel twisted optical lattice, revealing diverse phases and vortex phenomena driven by inter-species interactions.

Contribution

It introduces a new spin-1 twisted optical lattice system where moiré patterns arise from atomic interactions, expanding moiré physics into spinor Bose gases.

Findings

Identification of multiple ground state phases including ferromagnetic, antiferromagnetic, and polar.

Observation of vortex pair formation during quench dynamics.

Demonstration of moiré pattern effects driven by inter-species interactions in spin-1 gases.

Abstract

Recently, the simulation of moir\'e physics using cold atom platforms has gained significant attention. These platforms provide an opportunity to explore novel aspects of moir\'e physics that go beyond the limits of traditional condensed matter systems. Building on recent experimental advancements in creating twisted bilayer spin-dependent optical lattices for pseudospin-1/2 Bose gases, we extend this concept to a trilayer optical lattice for spin-1 Bose gases. Unlike conventional moir\'e patterns, which are typically induced by interlayer tunneling or interspin coupling, the moir\'e pattern in this trilayer system arises from inter-species atomic interactions. We investigate the ground state of Bose-Einstein condensates loaded in this spin-1 twisted optical lattice under both ferromagnetic and antiferromagnetic interactions. We find that the ground state forms a periodic pattern of distinct phases in the homogeneous case, including ferromagnetic, antiferromagnetic, polar, and broken axial symmetry phases. Additionally, by quenching the optical lattice potential strength, we examine the quench dynamics of the system above the ground state and observe the emergence of topological excitations such as vortex pairs. This study provides a pathway for exploring the rich physics of spin-1 twisted optical lattices and expands our understanding of moir\'e systems in synthetic quantum platforms.