Interaction induced moir\'e systems in twisted bilayer optical lattices

TL;DR

This paper proposes a new mechanism for moiré lattice formation in twisted bilayer optical lattices, driven by interlayer interactions rather than tunneling, leading to novel quantum phases observable in cold atom experiments.

Contribution

It introduces a dynamical moiré lattice formation mechanism in cold atoms via interlayer interactions, distinct from traditional static tunneling-based moiré systems.

Findings

Discovery of interaction-induced moiré phases including Mott insulator and superfluid states.

Identification of phases with symmetry breaking, interlayer coupling, and localization phenomena.

Potential for experimental realization in current cold atom setups.

Abstract

Moir\'e related physics in twisted bilayer two-dimensional (2D) materials has attracted widespread interest in condensed matter physics. Simulation of moir\'e related physics in cold atom platform is expected to outperform the 2D materials thanks to its advantage of higher tunablility. Here, we demonstrate that, the cold atom platform enables a new mechanism of moir\'e lattice formation, induced by interlayer interaction with intrinsic "dynamical" character, in contrast to conventional moir\'e lattice induced by "static" ways such as single-particle interlayer tunneling. Specifically, we consider a twisted bilayer Bose-Hubbard model with vanishing interlayer tunneling, and the bilayer is solely coupled through interlayer interaction that originates from contact interaction of atoms. We find that this system hosts a plethora of novel phases unique to this dynamical lattice, including a variety of Mott insulator (MI) and superfluid (SF) phases either preserving or breaking moir\'e lattice symmetry, phases with one layer in SF and the other in MI, "interlocked" MI, and self-localized phases at commensurate twist angles, which exhibits the characteristics of Bose glass and quasi-many-body localization in the absence of (quasi)disorder or quasicrystalline lattices. Our prediction can be readily observed in current experimental setup of twisted bilayer optical lattices, opening up new avenues for exploring the rich physics of interaction induced moir\'e systems in cold atoms.