Tunable non-Hermiticity through reservoir engineering

We experimentally demonstrate tunable non-Hermitian coupling in an atomic-vapor cell where atomic coherences in different optical channels are dissipatively coupled through atomic motion. Introducing a far-detuned light wall in the reservoir between the optical channels, we decorate the inter-channel coupling term so that it can be switched from dissipative to coherent. The tunable non-Hermiticity is then confirmed through measurements of the inter-channel light transport where the light-wall-induced phase shift is directly probed. Based on the tunable non-Hermiticity, we further discuss an exemplary scheme in which our setup can serve as a building block for the experimental study of exotic non-Hermitian criticality. (c) 2022 Chinese Laser Press

Automated summary

In this experiment, tunable non-Hermitian coupling is demonstrated in an atomic-vapor cell, where atomic coherences in different optical channels are dissipatively coupled through atomic motion. By introducing a far-detuned light wall in the reservoir between the optical channels, the inter-channel coupling term can be switched from dissipative to coherent. The tunable non-Hermiticity is confirmed through measurements of the inter-channel light transport, and the setup can serve as a building block for the experimental study of exotic non-Hermitian criticality.