Obstructed Atomic Insulators and Superfluids of Fermions Coupled to ${\mathbb{Z}}_2$ Gauge Fields

Abstract

We study spin-$\frac{1}{2}$ fermions coupled to ${\mathbb{Z}}_2$ gauge fields on a lattice. We show how a spatial modulation of the fermion hopping allows for the realization of various obstructed atomic insulators that host higher-order band topology. Studying the effect of quantum dynamics of the gauge fields within a simplified model, we find a rich phase diagram of this system with a number of superfluid phases arising from the attractive interactions meditated by the gauge fields. A key finding of this work is that the evolution from the Bardeen-Cooper-Schrieffer (BCS) superfluid state to a Bose-Einstein condensate (BEC) of tightly bound pairs occurs via the realization of these different superfluid phases separated by first-order transitions.

7 pages, 4 figures, 1 table, supplemental material (6 pages, 1 figure)

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Cited by in corpus (1)

• Critical States of Fermions with ${\mathbb{Z}}_2$ Flux Disorder