Phys.org February 8, 2023
In the past two decades, quantum key distribution networks based on telecom fibers have been implemented on metropolitan and intercity scales. One of the bottlenecks lies in the exponential decay of the key rate with respect to the transmission distance. Recently proposed schemes mainly focus on achieving longer distances by creating a long-arm single-photon interferometer over two communication parties. Despite their advantageous performance over long communication distances, the requirement of phase locking between two remote lasers is technically challenging. By adopting the recently proposed mode-pairing idea, researchers in China have demonstrated high-performance quantum key distribution without global phase locking. Using two independent off-the-shelf lasers, they showed a quadratic key-rate improvement over the conventional measurement-device-independent schemes in the regime of metropolitan and intercity distances. For longer distances, they boosted the key rate performance by 3 orders of magnitude via 304 km commercial fiber and 407 km ultralow-loss fiber. According to the researchers their scheme is ready to be widely used in future intercity quantum communication networks… read more. TECHNICAL ARTICLE
A demonstration of quantum entanglement, a key mechanic behind quantum communication. Credit: CFP