Fermionic Superfluid from a Bilayer Band Insulator in an Optical Lattice

TL;DR

This paper proposes a new method to realize a high-temperature fermionic superfluid in an optical bilayer lattice system by tuning interactions in a low entropy band-insulator state, potentially overcoming cooling challenges.

Contribution

It introduces a model for achieving fermionic superfluidity in optical lattices using a bilayer band insulator, with detailed analysis and Monte Carlo calculations demonstrating high transition temperatures.

Findings

Superfluid transition temperature is of the order of the hopping energy.

The system suppresses competing orders like charge density waves.

Proposes a feasible experimental realization via shaken optical lattices.

Abstract

We propose a model to realize a fermionic superfluid state in an optical lattice circumventing the cooling problem. Our proposal exploits the idea of tuning the interaction in a characteristically low entropy state, a band-insulator in an optical bilayer system, to obtain a superfluid. By performing a detailed analysis of the model including fluctuations and augmented by a variational quantum Monte Carlo calculations of the ground state, we show that the superfluid state obtained has high transition temperature of the order of the hopping energy. Our system is designed to suppress other competing orders such as a charge density wave. We suggest a laboratory realization of this model via an orthogonally shaken optical lattice bilayer.