Microwave Photonics Parallel Quantum Key Distribution

TL;DR

This paper demonstrates a multiplexed quantum key distribution system using microwave photonics techniques, enabling multiple simultaneous keys over a single fiber with low error rates, advancing secure quantum communications.

Contribution

It presents the first successful implementation of a multiplexed BB84 QKD system combining subcarrier and wavelength division multiplexing over optical fibers.

Findings

Four independent channels at 10 kb/s each over 11 km with QBER < 2%.

First demonstration of a two-domain multiplexed QKD system.

Enables multi-user quantum key distribution over existing fiber networks.

Abstract

The incorporation of multiplexing techniques used in Microwave Photonics to Quantum Key Distribution (QKD) systems bring important advantages enabling the simultaneous and parallel delivery of multiple keys between a central station and different end-users in the context of multipoint access and metropolitan networks, or by providing higher key distribution rates in point to point links by suitably linking the parallel distributed keys. It also allows the coexistence of classical information and quantum key distribution channels over a single optical fibre infrastructure. Here we show, for the first time to our knowledge, the successful operation of a two domain (subcarrier and wavelength division) multiplexed strong reference BB84 quantum key distribution system. A four independent channel QKD system featuring 10 kb/s/channel over an 11 km link with Quantum Bit Error Rate (QBER) < 2 % is reported. These results open the way for multi-quantum key distribution over optical fiber networks.