Scientists achieve 1,000 km quantum key distribution

https://phys.org/news/2023-06-scientists-km-quantum-key.html

"high-speed intercity quantum communication... twin-field QKD sending-or-not-sending protocol improves relation between key rate and channel transmittance from linear η to square root η... ultra-low-loss fiber based on pure silica core, maximum attenuation 0.16 dB/km... ultra-low-noise superconducting single-photon detectors... noise single-photon detectors reduced to 0.02 cps... dual-band phase estimation scheme avoid spontaneous Raman scattering noise, noise below 0.01 Hz... key rate 0.0034 bps"

Related: Combating disruptive 'noise' in quantum communication

https://phys.org/news/2024-04-combating-disruptive-noise-quantum-communication.htm