Topological Flat Bands from Dipolar Spin Systems

TL;DR

This paper introduces a system of dipolar spins arranged in a 2D array that naturally forms topological nearly flat bands, enabling exploration of exotic quantum phases with potential experimental implementations.

Contribution

It presents a novel method to realize topological flat bands using driven dipolar spin systems, combining theoretical analysis and experimental feasibility.

Findings

Topological nearly flat bands can be engineered in dipolar spin arrays.

Exact diagonalization reveals superfluid, crystalline, and supersolid phases.

The system's bandgap can surpass the bandwidth, indicating robust topological features.

Abstract

We propose and analyze a physical system that naturally admits two-dimensional topological nearly flat bands. Our approach utilizes an array of three-level dipoles (effective S = 1 spins) driven by inhomogeneous electromagnetic fields. The dipolar interactions produce arbitrary uniform background gauge fields for an effective collection of conserved hardcore bosons, namely, the dressed spin-flips. These gauge fields result in topological band structures, whose bandgap can be larger than the corresponding bandwidth. Exact diagonalization of the full interacting Hamiltonian at half-filling reveals the existence of superfluid, crystalline, and supersolid phases. An experimental realization using either ultra-cold polar molecules or spins in the solid state is considered.