Observation of reentrant metal-insulator transition in a random-dimer disordered SSH lattice

TL;DR

This paper reports the experimental observation of a reentrant metal-insulator transition in a photonic SSH lattice with random-dimer disorder, demonstrating extended states reappearing at higher disorder levels.

Contribution

It provides the first experimental verification of reentrant localization transition in a disordered SSH lattice using photonic systems, bridging theory and experiment.

Findings

Reentrant localization transition observed experimentally.

Extended eigenstates appear after initial localization.

Anomalous peak in participation ratio confirms reentrant behavior.

Abstract

The interrelationship between localization, quantum transport, and disorder has remained a fascinating focus in scientific research. Traditionally, it has been widely accepted in the physics community that in one-dimensional systems, as disorder increases, localization intensifies, triggering a metal-insulator transition. However, a recent theoretical investigation [Phys. Rev. Lett. 126, 106803] has revealed that the interplay between dimerization and disorder leads to a reentrant localization transition, constituting a remarkable theoretical advancement in the field. Here, we present the experimental observation of reentrant localization using an experimentally friendly model, a photonic SSH lattice with random-dimer disorder, achieved by incrementally adjusting synthetic potentials. In the presence of correlated on-site potentials, certain eigenstates exhibit extended behavior following the localization transition as the disorder continues to increase. We directly probe the wave function in disordered lattices by exciting specific lattice sites and recording the light distribution. This reentrant phenomenon is further verified by observing an anomalous peak in the normalized participation ratio. Our study enriches the understanding of transport in disordered mediums and accentuates the substantial potential of integrated photonics for the simulation of intricate condensed matter physics phenomena.