Modulation-assisted tunneling in laser-fabricated photonic Wannier-Stark ladders

TL;DR

This paper demonstrates control over localization and tunneling in laser-fabricated photonic lattices, enabling the creation of gauge fields through modulation-assisted tunneling and Wannier-Stark localization.

Contribution

It introduces a method to tune tunneling and localization in photonic lattices using laser fabrication and sinusoidal modulation, advancing photonic gauge field engineering.

Findings

Wannier-Stark localization increases with lattice curvature

Tunneling can be restored via sinusoidal modulation

Laser-fabricated modulations enable gauge field creation

Abstract

We observe Wannier-Stark localization in curved photonic lattices, realized using arrays of evanescently coupled optical waveguides. By correctly tuning the strength of inter-site coupling in the lattice, we observe that Wannier-Stark states become increasingly localized, and eventually fully localized to one site, as the curvature of the lattice is increased. We then demonstrate that tunneling can be successfully restored in the lattice by applying a sinusoidal modulation to the lattice position, an effect that is a direct analogue of photon-assisted tunneling. This precise tuning of the tunneling matrix elements, through laser-fabricated on-site modulations, opens a novel route for the creation of gauge fields in photonic lattices.