Quantum Key Distribution with Trusted Relay using an ETSI-compliant Software-Defined Controller

Quantum Key Distribution (QKD) is a mechanism that allows two entities to agree on a secret key over a quantum channel. Recently, commercially viable QKD technology appeared on the market and the European Telecommunications Standards Institute (ETSI) established a working group to standardize QKD for commercial applications. Several testbeds and pre-commercial QKD networks are being deployed in the world, all requiring sophisticated control mechanisms to enable key exchanges between non-adjacent nodes for remote applications. In this paper, we implement and evaluate a prototype that realizes the architecture defined by ETSI and uses trusted relay nodes to exchange keys between non-adjacent nodes. In particular, we present the Software-Defined Network (SDN) Controller and the Software-Defined QKD nodes designed to control the QKD experimental testbed in Milan, named PoliQI. We test the proposed prototype in an emulation environment, showing its advantages in inter-datacenter communication scenarios in terms of key delivery time and application acceptance ratio.