Engineering Ising-XY spin models in a triangular lattice via tunable artificial gauge fields

TL;DR

This paper reports the experimental realization of tunable gauge fields in a triangular lattice of ultracold atoms, revealing phase transitions and symmetry breaking phenomena relevant to Ising-XY spin models.

Contribution

It demonstrates the creation of tunable staggered gauge fields in a driven triangular lattice and explores their effects on superfluid ground states and phase transitions.

Findings

Observation of a thermally driven phase transition from ordered to disordered states.

Measurement of an Ising order parameter indicating Z2 symmetry breaking.

Magnetization curves consistent with theoretical predictions.

Abstract

Emulation of gauge fields for ultracold atoms provides access to a class of exotic states arising in strong magnetic fields. Here we report on the experimental realisation of tunable staggered gauge fields in a periodically driven triangular lattice. For maximal staggered magnetic fluxes, the doubly degenerate superfluid ground state breaks both a discrete Z2 (Ising) symmetry and a continuous U(1) symmetry. By measuring an Ising order parameter, we observe a thermally driven phase transition from an ordered antiferromagnetic to an unordered paramagnetic state and textbook-like magnetisation curves. Both the experimental and theoretical analysis of the coherence properties of the ultracold gas demonstrate the strong influence of the Z2 symmetry onto the condensed phase.