Ultracold quantum gases in triangular optical lattices

TL;DR

This paper reports on creating versatile triangular optical lattices for ultracold atoms, observing the superfluid-Mott insulator transition, and exploring spinor BEC dynamics, opening new avenues for quantum simulation and control.

Contribution

It introduces a three-beam setup for flexible lattice geometries and demonstrates the first detailed study of SF-MI transition and spinor BEC behavior in a triangular lattice.

Findings

Superfluid-Mott insulator transition observed and characterized.

Mean-field model describes spin dynamics below the transition.

Potential for tuning spin resonance via lattice and interaction parameters.

Abstract

Over the last years the exciting developments in the field of ultracold atoms confined in optical lattices have led to numerous theoretical proposals devoted to the quantum simulation of problems e.g. known from condensed matter physics. Many of those ideas demand for experimental environments with non-cubic lattice geometries. In this paper we report on the implementation of a versatile three-beam lattice allowing for the generation of triangular as well as hexagonal optical lattices. As an important step the superfluid-Mott insulator (SF-MI) quantum phase transition has been observed and investigated in detail in this lattice geometry for the first time. In addition to this we study the physics of spinor Bose-Einstein condensates (BEC) in the presence of the triangular optical lattice potential, especially spin changing dynamics across the SF-MI transition. Our results suggest that below the SF-MI phase transition, a well-established mean-field model describes the observed data when renormalizing the spin-dependent interaction. Interestingly this opens new perspectives for a lattice driven tuning of a spin dynamics resonance occurring through the interplay of quadratic Zeeman effect and spin-dependent interaction. We finally discuss further lattice configurations which can be realized with our setup.