Ultracold atoms in a square lattice with spin-orbit coupling: Charge order, superfluidity, and topological signatures

TL;DR

This study uses exact numerical methods to analyze ultracold fermions with spin-orbit coupling on a square lattice, revealing a supersolid ground state with unique charge, superfluid, and topological properties.

Contribution

It provides the first comprehensive, high-accuracy quantum Monte Carlo analysis of charge, spin, and pairing in a spin-orbit coupled lattice system, serving as a benchmark for future experiments.

Findings

Ground state is a supersolid with co-existing charge and superfluid order.

Superfluid contains both singlet and triplet pairs due to spin-orbit coupling.

Results serve as benchmarks for ultracold atom experiments on topological phases.

Abstract

We present an $\textit{ab initio}$, numerically exact study of attractive fermions in square lattices with Rashba spin-orbit coupling. The ground state of this system is a supersolid, with co-existing charge and superfluid order. The superfluid is composed of both singlet and triplet pairs induced by spin-orbit coupling. We perform large-scale calculations using auxiliary-field quantum Monte Carlo to provide the first full, quantitative description of the charge, spin, and pairing properties of the system. In addition to characterizing the exotic physics, our results will serve as essential high-accuracy benchmarks for the intense theoretical and especially experimental efforts in ultracold atoms to realize and understand an expanding variety of quantum Hall and topological superconductor systems.