# Observation of twist-induced geometric phases and inhibition of optical tunneling via Aharonov-Bohm effects

## TL;DR

This paper reports the first experimental observation of twist-induced geometric phases and Aharonov-Bohm-like suppression of optical tunneling in a twisted multi-core fiber system, revealing new quantum-inspired effects in optics.

## Contribution

It demonstrates for the first time that optical tunneling in a twisted fiber system can exhibit geometric phases and tunneling suppression analogous to Aharonov-Bohm effects.

## Key findings

- Observation of geometric phase accumulation in optical tunneling.
- Identification of conditions for tunneling suppression at specific twist rates.
- Experimental demonstration of Aharonov-Bohm-like effects in fiber optics.

## Abstract

Geometric phases appear ubiquitously in many and diverse areas of physical sciences, ranging from classical and molecular dynamics to quantum mechanics and solid-state physics. In the realm of optics, similar phenomena are known to emerge in the form of a Pancharatnam-Berry phase whenever the polarization state traces a closed contour on the Poincare sphere. While this class of geometric phases has been extensively investigated in both free-space and guided wave systems, the observation of similar effects in photon-tunneling arrangements has so far remained largely unexplored. Here, for the first time, we experimentally demonstrate that the tunneling or coupling process in a twisted multi-core fiber system can display a chiral geometric phase accumulation-analogous to that of the Aharonov-Bohm effect resulting from the presence of a nonzero magnetic flux. In our experiments, the tunneling geometric phase is manifested through the interference of the corresponding supermodes. In this system, and for specific values of the twist rate, the tunneling between opposite cores ceases, thus signifying an Aharonov-Bohm suppression of tunneling. Our work provides the first observation of this intriguing effect in an optical setting.

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Source: https://tomesphere.com/paper/1908.01715