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Optica Advanced Photonics Congress

A Multi-technology/Multi-domain QKD Deployment over a Telco Production Network: Practical Issues and Outcomes

Juan Pedro Fernández-Palacios, Felipe Jiménez, José Manuel Rivas-Moscoso, Antonio Pastor, Jesús Folgueira, Diego R. Lopez, Juan P. Brito, Vicente Martín

Published Jan 1, 2022• 2 citations
Publisher

Abstract

We present a setup for testing CV- and DV-QKD technology coexistence over a production network. We demonstrate multi-technology, multiband operation of QKD systems working both separately and in trusted-node configuration for intra- and inter-domain applications.
DOI
10.1364/networks.2022.neth2c.4

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Abstract QKD (Quantum Key Distribution) promises information-theoretical security by using quantum states to generate shared cryptographic key material and to reveal eavesdropping attempts through unavoidable physical disturbances. The practical value of this promise depends not only on quantum technologies such as DV-QKD, CV-QKD, entanglement-based QKD, MDI-QKD, and Twin-Field QKD, but also on authentication, post-processing, implementation quality, and operational architecture. Fiber-optic, satellite, and free-space QKD each impose distinct limits on distance, key rate, trusted nodes, costs, and resistance to side-channel attacks.
We demonstrate for the first time a four-node trusted-node-free metro network configuration with dynamic discrete-variable quantum key distribution DV-QKD networking capabilities across four optical network nodes. The network allows the dynamic deployment of any QKD link between two nodes of the network, while a QKD-aware centralised software-defined networking (SDN) controller is utilised to provide dynamicity in switching and rerouting. The feasibility of coexisting a quantum channel with carrier-grade classical optical channels where both the quantum and classical channels are in the C-band over field-deployed metropolitan networks and laboratory-based fibres (<10 km) is experimentally explored in terms of achievable quantum bit error rate, secret key rate as well as classical signal bit error rate. Moreover, coexistence analysis over multi-hops configuration using different switching scenarios is also presented. The secret key rate dropped 43% when coexisting one classical channel with 150 GHz spacing from the quantum channel for multiple links. This is due to the noise leakage from the Raman scattering into the 100 GHz bandwidth of the internal filter of the Bob DV-QKD unit. When coexisting four classical channels with 150 GHz spacing between quantum and the nearest classical channel, the quantum channel deteriorates faster due to the combination of Raman noise, other nonlinearities and high aggregated launch power causing the QBER value to exceed the threshold of 6% leading the SKR to reach a value of zero bps at a launch power of 7 dB per channel. Furthermore, the coexistence of a quantum channel and six classical channels through a field-deployed fibre test network is examined.
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