Chiral Ladders and the Edges of Chern Insulators

TL;DR

This paper demonstrates how cold atoms in optical ladders with synthetic magnetic fields can simulate topological phases, including Chern insulators, revealing edge states and phase transitions, and proposing experimental detection methods.

Contribution

It introduces a new platform using optical ladders to realize and study topological phases and edge states of Chern insulators with feasible experimental schemes.

Findings

Optical ladders can simulate spin-orbit coupling.

Energy bands reproduce chiral edge modes of Chern insulators.

Topological phase transition can be realized in ladder systems.

Abstract

The realization and detection of topological phases with ultracold atomic gases is at the frontier of current theoretical and experimental research. Here, we identify cold atoms in optical ladders subjected to synthetic magnetic fields as readily realizable bridges between one-dimensional spin-orbit (time reversal) topological insulators and two-dimensional Chern insulators. We reveal three instances of their promising potential: i) they realize spin-orbit coupling, with the left-right leg degree of freedom playing the role of an effective spin, ii) their energy bands and eigenstates exactly reproduce the topological chiral edge modes of two-dimensional Chern insulators, and iii) they can be tailored to realize a topological phase transition from a trivial to a topological insulating phase. We propose realistic schemes to observe the chiral and topological properties of ladder systems with current optical lattice-based experiments. Our findings open a door to the exploration of the physics of the edges of Chern insulators and to the realization of spin-orbit coupling and topological superfluid phases with ultracold atomic gases.