Pedagogic QKD
The audience makes a key difference
I setup a pedagogic version—based on a physics education paper—of the BB84 QKD protocol in our lab as seen above. This gave Dr. Tony Appollaro and me the opportunity to write a didactic article about QKD for the Times of Malta, give an online presentation at the European Quantum Week 2020, and present it to students visiting our group and laboratory at the University.
The scheme enables the two communicating parties—each located on one table—to establish an encryption key for their messages with a quantum and a classical communication channel. The quantum channel is setup on the optical table, while the classical communication channel is placed on the tables.
A potential hacker can eavesdrop on the classical channel without being detected. However, eavesdropping on the quantum channel, with the beam splitter photodetector and oscilloscope in the middle of the optical table, will inevitably leave a trace for the two communicating parties. They know that someone is listening in on their conversation and can act accordingly to keep their information secret.