Proof-of-principle long-distance Sagnac twin-field quantum key distribution network
Researchers experimentally demonstrated a proof-of-principle three-user Sagnac twin-field QKD network spanning 127 km using single-photon avalanche detectors. This setup successfully achieved a stable interference visibility of 93% and generated a key rate of $1.398 imes 10^{-5}$ bits per pulse over a lossy channel, proving a practical method for long-distance QKD without active phase stabilization.