Computation and Cryptography in the presence of Closed Timelike Curves
Charles H. Bennett
IBM Watson Research Center
Place: CAS 226 (725 Commonwealth Ave)
Time: Feb 24, 3pm
Abstract
We discuss various models of closed timelike curves (CTCs), and their utility for increasing the distinguishability of nonorthogonal quantum states and for speeding up hard computations. In the most widely used model, Deutsch’s 1991 mixed-state-fixed-point model, we show that CTCs are of no help in quantum state discrimination and may not be of much help for speeding up hard computations. (Joint work with Debbie Leung, Graeme Smith, and John Smolin.) arXiv 0908.3023.
The Speaker
Charles H. Bennett, an IBM Fellow at IBM Research, is best known for exploring deep interconnections between physics and information. Again and again, he introduced approaches that may have sounded exotic first, but in a few years became a major object of study. The thermodynamics of computing, reversible computing, logical depth, random oracles belong to the early work. Bennett discovered in the 1980’s, with Gilles Brassard, the concept of quantum cryptography, then in the early 1990’s, in the company of several others, quantum teleportation. These and numerous other results make him one of the founding fathers of modern quantum information theory. Bennett is a Fellow of the American Physical Society and a member of the National Academy of Sciences. He was awarded the 2008 Harvey Prize by the Technion and the 2006 Rank Prize in opto-electronics.