Abstract
Interacting cold-atomic gases in optical lattices offer an experimental approach to outstanding problems of many body physics. One important example is the interplay of interaction and topology which promises to generate a variety of exotic phases such as the fractionalized Chern insulator or the topological Mott insulator. Both theoretically understanding these states of matter and finding suitable systems that host them have proven to be challenging problems. Here we propose a cold-atom setup where Hubbard on-site interactions give rise to spin liquid-like phases: weak and strong topological Mott insulators. They represent the celebrated paradigm of an interacting and topological quantum state with fractionalized spinon excitations that inherit the topology of the non-interacting system. Our proposal shall help to pave the way for a controlled experimental investigation of this exotic state of matter in optical lattices. Furthermore, it allows for the investigation of a dimensional crossover from a two-dimensional quantum spin Hall insulating phase to a three-dimensional strong topological insulator by tuning the hopping between the layers.
Highlights
Interacting cold-atomic gases in optical lattices offer an experimental approach to outstanding problems of many body physics
We show that the 2D system, which effectively consists of two time-reversed copies of massive Dirac Hamiltonians, can be tuned to a 3D weak or strong topological insulator just by varying a single hopping parameter
The spin mixing term c induces spin flips if the particle moves along the xaxis, and the l-term describes a staggering of the optical lattice potential along the x-direction
Summary
Interacting cold-atomic gases in optical lattices offer an experimental approach to outstanding problems of many body physics. We propose a cold-atom setup where Hubbard on-site interactions give rise to spin liquid-like phases: weak and strong topological Mott insulators. They represent the celebrated paradigm of an interacting and topological quantum state with fractionalized spinon excitations that inherit the topology of the non-interacting system. Cold-atom setups provide platforms for the realization of novel phases of matter and new phenomena that have never been observed in the solid state so far Examples of the latter is the interaction driven Mott-superfluid quantum phase transition in the Bose-Hubbard model[4] or SU(N) magnetism using alkalineearth atoms[5]. Note that this notion of a topological Mott insulator, which will be used in this paper, crucially differs from that of the proposal in Ref. 41 (see Supplementary Discussion S1)
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