Conferencias y seminarios
Viernes 13 de Enero de 2017
Auditorio Ramón Picarte DCC (3er. piso edificio norte, Beauchef 851)
"Public randomness: harvesting it, using it, and making it trustworthy"
Charles H. Bennett, IBM Fellow, Thomas J. Watson Research Center, Yorktown Heights, NY USA
Trusted public randomness has many uses, in fair decision-making (e.g. lotteries), negotiation, and authentication (e.g. by narrowing the time interval during which a video or other recording of a purported event can have been made). Quantum and chaotic physical processes offer many sources of in-principle unpredictability. Among these, Bell-violating quantum correlations give operators of a randomness beacon the greatest confidence that nature is not deceiving them, that the apparent randomness they observe is fresh and real. A greater problem, not mitigated by Bell violations, is that a beacon may be (or may be suspected of being) corrupt, releasing data that is not fresh, but has been secretly pre-shared with accomplices. This can be prevented by using a single publicly observable natural beacon (e.g. an astronomical noise source) beyond anyone's control, or by combining the results of many humanly-operated beacons that are geographically and administratively independent, into a result whose randomness cannot be compromised by any proper subset of them.
Charles H. Bennett was born in 1943, the son of music teachers. He received his PhD from Harvard in 1971. Since coming to IBM Reseach in 1972, he has worked on various aspects of the relation between physics and information. In 1973, building on the work of IBM's Rolf Landauer, he showed that general-purpose computation can be performed with arbitrarily little energy consumption per step because it avoids throwing away information about past logical states; and in 1982 he proposed the currently accepted resolution of the Maxwell's demon paradox, attributing the demon's inability to violate the Second Law to the thermodynamic cost of destroying, rather than acquiring, information. In collaboration with Gilles Brassard of the University of Montreal he developed a practical system of quantum cryptography, allowing secure communication between parties who share no secret information initially, and with the help of John Smolin built a working demonstration of it in 1989.
In 1993 Bennett and Brassard, in collaboration with Claude Crepeau, Richard Jozsa, Asher Peres, and William Wootters, discovered "quantum teleportation," in which the complete information in a system is decomposed into a classical message and quantum entanglement, then reassembled from these ingredients in a new location to produce an exact replica of the original quantum state that was destroyed in the sending process.
In recent years he has been interested in characterizing the conditions (including thermal disequilibrium) that lead to the emergence of classical correlations and computationally complex structures from quantum laws, in both terrestrial and cosmological settings.
Bennett is an IBM Fellow, a Fellow of the American Physical Society, and a member of the US National Academy of Sciences. He is a recipient of the Rank Prize, the Harvey Prize, the Okawa Prize, and four honorary doctorates. He is married with three grown children and seven grandchildren.