Geometry and superfluidity of the flat band in a non-Hermitian optical lattice

• URL: http://arxiv.org/abs/2101.00985v2
• Date: Mon, 17 May 2021 11:08:32 GMT
• Title: Geometry and superfluidity of the flat band in a non-Hermitian optical lattice
• Authors: Peng He, Hai-Tao Ding, Shi-Liang Zhu
• Abstract summary: We show that the interplay between the skin effect and flat-band localization leads to exotic localization properties. A relation between the superfluid weight and non-Hermitian quantum metric of the quantum states manifold is built.
• Score: 1.8305518556327907
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We propose an ultracold-atom setting where a fermionic superfluidity with attractive s-wave interaction is uploaded in a non-Hermitian Lieb optical lattice. The existence of a real-energy flat band solution is revealed. We show that the interplay between the skin effect and flat-band localization leads to exotic localization properties. We develop a multiband mean-field description of this system and use both order parameters and superfluid weight to describe the phase transition. A relation between the superfluid weight and non-Hermitian quantum metric of the quantum states manifold is built. We find non-monotone criticality depending on the non-Hermiticity, and the non-reciprocity prominently enhances the phase coherence of the pairing field, suggesting ubiquitous critical behavior of the non-Hermitian fermionic superfluidity.

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