Experimental Twin-Field Quantum Key Distribution Through Sending-or-Not-Sending

Understand

Channel loss seems to be the most severe limitation on the practical application of long distance quantum key distribution.

• The idea of twin-field quantum key distribution can improve the key rate from the linear scale of channel loss in the traditional decoy-state method to the square root scale of the channel transmittance.
• However, the technical demanding is rather tough because it requests single photon level interference of two remote independent lasers.
• Here, we adopt the technology developed in the frequency and time transfer to lock two independent lasers' wavelengths and utilize additional phase reference light to estimate and compensate the fiber fluctuation.