Feihu Xu, University of Toronto
In theory, quantum key distribution (QKD) provides information-theoretic security based on the laws of physics. Owing to the imperfections of real-life implementations, however, there is a big gap between the theory and practice of QKD. This gap has been recently exploited by several quantum hacking activities.
In this talk, I will give a brief tutorial of the security of practical QKD. I then address two important questions: i) How code-breakers can hack a real QKD system? ii) How code-makers can resolve the existing/potential attacks efficiently? I will show some simple attacks and the corresponding countermeasures in both the source and the measurement unit of a QKD implementation. In particular, I will discuss a novel protocol -- measurement-device-independent QKD (mdiQKD) -- that removes all side-channels from the measurement unit, arguably the most vulnerable part in QKD systems. mdiQKD offers a clear avenue towards secure QKD realizations. Finally, to generate truly random numbers for secure communication, I will present an ultrafast quantum random number generator prototype based on the quantum phase noise of a laser