Photonic interface between subcarrier wave and dual rail encodings

TL;DR

This paper presents a high-fidelity optical interface that converts between subcarrier wave and dual rail encodings, facilitating integration in long-distance quantum communication networks.

Contribution

It introduces and demonstrates a linear optical scheme for converting between subcarrier wave and dual rail encodings with over 92% fidelity.

Findings

Achieved >92% fidelity in encoding conversion

Enables compatibility of subcarrier wave QKD with quantum repeaters

Supports heterogeneous quantum network integration

Abstract

Quantum key distribution with multimode subcarrier wave encoding is propitious for being robust against environmental disturbance. For application in long-distance quantum communications this encoding has to be compatible with entanglement-assisted quantum repeaters that are commonly designed to work with dual rail encodings. We propose and demonstrate an interface between subcarrier wave and dual rail encodings with a fidelity of more than 92\% using a linear optical circuit. The developed scheme may find an application in future heterogeneous quantum networks that combine quantum key distribution with trusted and non-trusted nodes.