2013/04/30 by Julian Struck, Malte Weinberg, Christoph Ölschläger +8 · 1 citation
Physics and Astronomy · #cond-mat.quant-gas
paper · pdf · doi:10.1038/nphys2750
published as Nature Physics 9, 738-743 (2013)
arxiv created 2013/05/30 · arxiv updated 2013/11/06
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.