Realization of a fractional quantum Hall state with ultracold atoms

TL;DR

This paper reports the experimental realization of a fractional quantum Hall state using ultracold atoms in an optical lattice, demonstrating key features like fractional Hall conductivity and vortex structures, advancing topological quantum matter research.

Contribution

The authors successfully create a lattice version of a bosonic Laughlin state with ultracold atoms, capturing hallmark FQH features in a minimal system, which was previously unachieved in engineered quantum systems.

Findings

Observation of suppressed two-body interactions

Detection of vortex structures in density correlations

Measurement of fractional Hall conductivity of 0.6(2)

Abstract

Strongly interacting topological matter exhibits fundamentally new phenomena with potential applications in quantum information technology. Emblematic instances are fractional quantum Hall states, where the interplay of magnetic fields and strong interactions gives rise to fractionally charged quasi-particles, long-ranged entanglement, and anyonic exchange statistics. Progress in engineering synthetic magnetic fields has raised the hope to create these exotic states in controlled quantum systems. However, except for a recent Laughlin state of light, preparing fractional quantum Hall states in engineered systems remains elusive. Here, we realize a fractional quantum Hall (FQH) state with ultracold atoms in an optical lattice. The state is a lattice version of a bosonic $\nu=1/2$ Laughlin state with two particles on sixteen sites. This minimal system already captures many hallmark features of Laughlin-type FQH states: we observe a suppression of two-body interactions, we find a distinctive vortex structure in the density correlations, and we measure a fractional Hall conductivity of $\sigma_\text{H}/\sigma_0= 0.6(2)$ via the bulk response to a magnetic perturbation. Furthermore, by tuning the magnetic field we map out the transition point between the normal and the FQH regime through a spectroscopic probe of the many-body gap. Our work provides a starting point for exploring highly entangled topological matter with ultracold atoms.