Quantum secured gigabit optical access networks

TL;DR

This paper presents a method enabling secure quantum key distribution over gigabit optical access networks, overcoming splitter-induced noise issues, and demonstrating coexistence of quantum and classical signals for up to 128 users.

Contribution

A novel dual feeder approach compatible with standard GPON architectures that allows quantum and classical signals to coexist in passive optical networks.

Findings

Successful coexistence of multi-user QKD and full power data traffic

Supports up to 128 users in a quantum protected GPON network

Compatible with existing GPON infrastructure

Abstract

Optical access networks connect multiple endpoints to a common network node via shared fibre infrastructure. They will play a vital role to scale up the number of users in quantum key distribution (QKD) networks. However, the presence of power splitters in the commonly used passive network architecture makes successful transmission of weak quantum signals challenging. This is especially true if QKD and data signals are multiplexed in the passive network. The splitter introduces an imbalance between quantum signal and Raman noise, which can prevent the recovery of the quantum signal completely. Here we introduce a method to overcome this limitation and demonstrate coexistence of multi-user QKD and full power data traffic from a gigabit passive optical network (GPON). The dual feeder implementation is compatible with standard GPON architectures and can support up to 128 users, highlighting that quantum protected GPON networks could be commonplace in the future.