Scientists at the National Institute for Standards and Technology published an article about their new prototype Quantum Key Distribution system. The new system is able to send quantum keys for encryption over 10 km through one fiber optic wire. This new system is capable of sending the 'one-time pad' encryption, which is theoretically unbreakable.

This NIST QKD system works using an 'up-converting' single photons for better detection. This means that they are increasing the wavelength of a photon from 1310 nm to 710 nm so that each individual photon can be detected by a low-noise detector, in this case a silicon-based avalanche photo diode (Si-APD).

Up-Conversion QKD research
Article from PhysOrg