Orbital angular momentum photonic quantum interface

TL;DR

This paper demonstrates the first experimental quantum interface for orbital angular momentum-carrying photons, enabling wavelength conversion while preserving photon coherence, which is crucial for quantum communication networks.

Contribution

It introduces a novel quantum interface for OAM photons using a nonlinear crystal in an optical cavity, bridging wavelength gaps in quantum communication.

Findings

Successful wavelength up-conversion of OAM photons

Preservation of single-photon coherence during conversion

Strong similarity in spatial structures of input and output photons

Abstract

Light carrying orbital angular momentum (OAM) has great potential in enhancing the information channel capacity in both classical and quantum optical communications. Long distance optical communication requires the wavelengths of light are situated in the low-loss communication windows, but most quantum memories currently being developed for use in a quantum repeater work at different wavelengths, so a quantum interface to bridge the wavelength gap is necessary. So far, such an interface for OAM-carried light has not been realized yet. Here, we report the first experimental realization of a quantum interface for a heralded single photon carrying OAM using a nonlinear crystal in an optical cavity. The spatial structures of input and output photons exhibit strong similarity. More importantly, single-photon coherence is preserved during up-conversion as demonstrated.