Beecroft Building, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU
Dr Paul Burdekin, University of Oxford
Abstract
Secure communication depends on sharing secret keys, and throughout history, sharing them has been the weak point. Quantum key distribution (QKD) promises security guaranteed by physics, yet real systems have been hacked through imperfect devices, and fibre loss limits how far keys can be sent. In this talk, I will explain how measurement-device-independent (MDI) QKD closes the most common hacking attacks, and how quantum memories can extend the reach of secure quantum networks. I will then present our recent results with telecom-wavelength memories in warm rubidium vapour. Our new rephasing protocol extends storage time fifty-fold without adding noise, while also enabling multimode storage and processing of photons inside the memory. Finally, I will show how, in collaboration with Toshiba, these capabilities lead to a new MDI-QKD protocol in which a single memory can outperform existing schemes.