We have successfully demonstrated free-space BB84 and BBM92 protocol over 200 meter.

Free space BB84 protocol in the field

The laser driver circuit and RNG (Random Number Generator) is developed within PRL. Given below are the first results on parameter estimation of BB84 protocol using WCP (Weak Coherent Pulse) over 200 meters in NLOS Channel. Channel has a transmissivity of 70% with the driving frequency of laser around 5 MHz and mean photon number (µ) of 0.3.

QBER and Key rate are given above on some of the sets from the experiment. The average Sift Key rate is around 200 Kbps and secure key rate is around 150 Kbps.

Free space BBM92 protocol in the field

We also have demonstrated the Entanglement distribution over 200 meters with Bell-CHSH violation of 2.54.

Again for the same channel we have done BBM92 Protocol with Sift Key rate of 5 Kbps. Below table shows the parameter estimation of the Protocol. The Table shows the coincidence counts (CC) in the polarization state between Alice and Bob.

For more information, refer to article on arxiv arXiv:2112.11961.