In this episode of Entangled with... we speak with Professor Norbert Lütkenhaus, a professor at the Institute for Quantum Computing and the Physics department of the University of Waterloo, as well as the head of the Optical Quantum Communication Theory Group. We discuss quantum cryptography and various protocols for quantum key distribution, as well as both the theoretical and practical challenges associated with QKD, and he shares his outlook on the future of commercializing and incorporating this technology into our current communication infrastructure.