Daylight Quantum Key Distribution in a Free-Space Channel Using Entangled Photons Emitted by a Quantum Dot Device

Quantum key distribution (QKD) is at the heart of future secure quantum communication networks as it can enhance security of classical communication strategies. Although prepare-and-measure protocols are the most widely used in practical applications, entangled-based QKD is promising for further improving the degree of security and developing free-trusted node networks. However, free-space link implementations for single photon transmission suffer daylight operations and few works have been demonstrated in this regime. Furthermore, entangled-based QKD in air link has been demonstrated only using spontaneous parametric down-conversion (SPDC) sources and never tested using quantum dot devices, despite they potentially overcome SPDC performances in terms of effi-ciency and fidelity of the QKD protocol.