Experimental observation of Aharonov-Bohm cages in photonic lattices

TL;DR

This paper demonstrates the experimental creation of synthetic magnetic flux in photonic lattices, leading to Aharonov-Bohm cages where light localization occurs due to flat energy bands, enabling studies of gauge fields and topological effects.

Contribution

The work reports the first experimental realization of Aharonov-Bohm cages in photonic systems with tunable synthetic magnetic flux and explores their topological properties.

Findings

Observation of flat energy bands at half flux quantum

Demonstration of light localization via Aharonov-Bohm caging

Edge state dynamics connected to topological Creutz ladder

Abstract

We report on the experimental realization of a uniform synthetic magnetic flux and the observation of Aharonov-Bohm cages in photonic lattices. Considering a rhombic array of optical waveguides, we engineer modulation-assisted tunneling processes that effectively produce non-zero magnetic flux per plaquette. This synthetic magnetic field for light can be tuned at will by varying the phase of the modulation. In the regime where half a flux quantum is realized in each plaquette, all the energy bands dramatically collapse into non-dispersive (flat) bands and all eigenstates are completely localized. We demonstrate this Aharonov-Bohm caging by studying the propagation of light in the bulk of the photonic lattice. Besides, we explore the dynamics on the edge of the lattice and discuss how the corresponding edge states can be continuously connected to the topological edge states of the Creutz ladder. Our photonic lattice constitutes an appealing platform where the interplay between engineered gauge fields, frustration, localization and topological properties can be finely studied.