Physicist Charles Bennett Wins Turing Award for Quantum Breakthroughs

Charles Bennett is a physicist who spent his career at IBM asking what the laws of physics permit a computer to do. He's not primarily an experimentalist and didn't build machines, but his contribution was to notice that certain questions about information had physical answers.

Bennett began working on the principles of thermodynamics in computing with his colleague Rolf Landauer in 1961. They established that erasing a bit of information has an unavoidable thermodynamic cost, which is dissipated as heat. Bennett took this principle and worked out its consequences, discovering that computation can be performed reversibly without any necessary expenditure of energy.

One of his most significant contributions was the BB84 quantum key distribution protocol in 1984, co-authored with Gilles Brassard. This protocol allowed two people who had never met to agree on a string of random bits and know for certain whether anyone had listened in. The security didn't rest on any assumption about how much computing power an eavesdropper had, but rather on the fact that measuring a quantum system disturbs it.