Phys.org March 25, 2024 An on-demand source of bright entangled photon pairs is needed for quantum key distribution (QKD) and quantum repeaters. The generation of such pairs is based on spontaneous parametric down-conversion (SPDC) in non-linear crystals. However, SPDC pair extraction efficiency is very limited when operating at near-unity fidelity. In principle quantum dots in photonic nanostructures can overcome this limit, but the devices with high entanglement fidelity have low pair extraction efficiency. An international team of researchers (Canada, the Netherlands, Sweden) has demonstrated a measured peak entanglement fidelity of 97.5% ± 0.8% and pair extraction efficiency of 0.65% from an InAsP […]
Tag Archives: QKD
Twin-field quantum key distribution (QKD) across an 830-km fibre
Phys.org January 24, 2022 As the photons carrying signals cannot be amplified or relayed via classical optical techniques to maintain quantum security, the transmission loss of the channel limits its achievable distance. An international team of researchers (Spain, Japan, Canada, China, Russia) has designed an experimental QKD system that could tolerate a channel loss beyond 140 dB and obtain a secure distance of 833.8 km. Furthermore, the optimized four-phase twin-field protocol and set-up make its secure key rate more than two orders of magnitude greater than previous records over similar distances… read more. TECHNICAL ARTICLE 1 , Open Access 2