Gilles Brassard

I shall discuss two topics, which are loosely connected by Artur Ekert's E91 protocol, whose subtitles are (1) How quantum cryptography came to be, and (2) Who told you that Nature is nonlocal? The first tale will cover the period from Stephen Wiesner's seminal Conjugate Coding to Ekert's protocol; the second tale will start with EPR 1935, evolve through John Bell's 1964 seminal paper to the experiments that led to the 2022 Nobel Prize in Physics that purport to force us to renounce local realism, and culminate with my reasons to believe that Nature is local and realistic nevertheless.

The late Rolf Landauer has once claimed that "information is physical". The main point of this talk is to argue that "physics is informational"! At the moment, quantum information theory is replete with beautiful theorems on what is and is not possible according to quantum mechanics. For example, quantum key distribution is possible but quantum bit commitment is not. But the axioms of quantum mechanics are strange and ad hoc, reflecting at best the history that led to discovering this new world order. It's time to pause and reflect on what is really fundamental and what are merely consequences. Could information be the answer? (This is joint work with Christopher Fuchs)

Can quantum mechanics be harnessed to provide unconditionally secure bit commitment schemes and other cryptographic primitives beyond key distribution? This was believed possible for several years until Mayers came along with his proof that the "provably" secure BCJL bit commitment scheme was fatally flawed.