Observation of Parity-Time Symmetry in Optically Induced Atomic Lattices

TL;DR

This paper reports the experimental creation of PT-symmetric optical lattices in an atomic system, demonstrating symmetry breaking and phase shifts, advancing the understanding of non-Hermitian physics in atomic media.

Contribution

It introduces a novel atomic system implementation of PT-symmetric optical lattices with tunable parameters and observes symmetry breaking phenomena.

Findings

Observation of PT-symmetry breaking through phase-shift jumps

Reconfigurable and controllable PT-symmetric waveguide arrays

Experimental demonstration in a four-level atomic system

Abstract

We experimentally demonstrate PT-symmetric optical lattices with periodical gain and loss profiles in a coherently-prepared four-level N-type atomic system. By appropriately tuning the pertinent atomic parameters, the onset of PT-symmetry breaking is observed through measuring an abrupt phase-shift jump between adjacent gain and loss waveguides. The experimental realization of such readily reconfigurable and effectively controllable PT-symmetric waveguide array structure sets a new stage for further exploiting and better understanding the peculiar physical properties of these non-Hermitian systems in atomic settings.