d-Wave Superfluidity in Optical Lattices of Ultracold Polar Molecules

TL;DR

This paper explores the conditions under which d-wave superfluidity can be realized in ultracold polar molecules in optical lattices, highlighting the effects of various interactions and proposing experimental schemes.

Contribution

It provides a phase diagram for polar molecules in a checkerboard lattice and identifies how different interactions influence d-wave superfluidity.

Findings

d-wave superfluidity occurs in specific parameter regimes

density-density interactions suppress superfluidity

spin-density and Ising interactions enhance superfluidity

Abstract

Recent work on ultracold polar molecules, governed by a generalization of the t-J Hamiltonian, suggests that molecules may be better suited than atoms for studying d-wave superfluidity due to stronger interactions and larger tunability of the system. We compute the phase diagram for polar molecules in a checkerboard lattice consisting of weakly coupled square plaquettes. In the simplest experimentally realizable case where there is only tunneling and an XX-type spin-spin interaction, we identify the parameter regime where d-wave superfluidity occurs. We also find that the inclusion of a density-density interaction destroys the superfluid phase and that the inclusion of a spin-density or an Ising-type spin-spin interaction can enhance the superfluid phase. We also propose schemes for experimentally realizing the perturbative calculations exhibiting enhanced d-wave superfluidity.