Snapshot-based detection of $\frac{1}{2}$-Laughlin states: coupled chains and central charge

TL;DR

This paper demonstrates that the central charge of topologically ordered states like the Laughlin state can be directly measured in cold atom experiments using density-matrix renormalization-group simulations and snapshot-based schemes, aiding detection of topological phases.

Contribution

It introduces a method to measure the central charge via number entropy in cold atom setups and identifies a phase transition to the Laughlin state in coupled chains under magnetic flux.

Findings

Transition from trivial to Laughlin state at flux α=1/4

Central charge measurement distinguishes phases

Proposed experimental scheme for central charge estimation

Abstract

Experimental realizations of topologically ordered states of matter, such as fractional quantum Hall states, with cold atoms are now within reach. In particular, optical lattices provide a promising platform for the realization and characterization of such states, where novel detection schemes enable an unprecedented microscopic understanding. Here we show that the central charge can be directly measured in current cold atom experiments using the number entropy as a proxy for the entanglement entropy. We perform density-matrix renormalization-group simulations of Hubbard-interacting bosons on coupled chains subject to a magnetic field with $\alpha=\frac{1}{4}$ flux quanta per plaquette. Tuning the inter-chain hopping, we find a transition from a trivial quasi-one dimensional phase to the topologically ordered Laughlin state at magnetic filling factor $\nu=\frac{1}{2}$ for systems of three or more chains. We resolve the transition using the central charge, on-site correlations, momentum distributions and the many-body Chern number. Additionally, we propose a scheme to experimentally estimate the central charge from Fock basis snapshots. The model studied here is experimentally realizable with existing cold atom techniques and the proposed observables pave the way for the detection and classification of a larger class of interacting topological states of matter.