4 research outputs found
Engineering Ising-XY spin models in a triangular lattice via tunable artificial gauge fields
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
Non-Abelian gauge fields and topological insulators in shaken optical lattices
Time-periodic driving like lattice shaking offers a low-demanding method to
generate artificial gauge fields in optical lattices. We identify the relevant
symmetries that have to be broken by the driving function for that purpose and
demonstrate the power of this method by making concrete proposals for its
application to two-dimensional lattice systems: We show how to tune frustration
and how to create and control band touching points like Dirac cones in the
shaken kagom\'e lattice. We propose the realization of a topological and a
quantum spin Hall insulator in a shaken spin-dependent hexagonal lattice. We
describe how strong artificial magnetic fields can be achieved for example in a
square lattice by employing superlattice modulation. Finally, exemplified on a
shaken spin-dependent square lattice, we develop a method to create strong
non-Abelian gauge fields.Comment: 5 pages, 4 figures + supplemental material (2 pages, 1 figure).
Accepted for publication in Phys. Rev. Lett.. Minor changes with respect to
version 2 to improve presentatio