Charles Bennett and Gilles Brassard

Bennett is a physicist at IBM Research; Brassard, a computer scientist at the Université de Montréal. They met by chance on a beach in Puerto Rico in 1979 and began a collaboration that lasted decades.

Building on Stephen Wiesner's unpublished idea of quantum money from the late 1960s, in 1984 they presented BB84, a method for two people to agree on a secret key by sending single photons in randomly chosen polarisations. Because an unknown quantum state cannot be copied, any eavesdropper disturbs the photons and is detected.

In 1993, with Claude Crépeau, Richard Jozsa, Asher Peres and William Wootters, they showed that an unknown quantum state can be transferred from one place to another using a shared entangled pair and two ordinary bits of communication. Nothing is sent faster than light and the original is destroyed. Bennett also worked on the thermodynamics of computation, showing that computing can in principle be done with no energy cost if it is reversible.

Quantum key distribution is already in commercial use, and teleportation is the standard way of moving quantum information in a quantum network. They received the 2023 ACM A. M. Turing Award, and shared the 2023 Breakthrough Prize with Deutsch and Shor.