Charles H. Bennett (computer scientist)

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Charles H. Bennett
Born 1943 (age 73–74)
Fields computer science
quantum information
Institutions Thomas J. Watson Research Center
Alma mater Brandeis University (BS 1964)
Harvard University (PhD 1970)
Doctoral advisor David Turnbull
Berni Alder
Known for Bennett's four laws of quantum information
Notable awards IBM Fellow

Charles Henry Bennett (b. 1943)[1] is a physicist, information theorist and IBM Fellow at IBM Research. Bennett's recent work at IBM has concentrated on a re-examination of the physical basis of information, applying quantum physics to the problems surrounding information exchange. He has played a major role in elucidating the interconnections between physics and information, particularly in the realm of quantum computation, but also in cellular automata[2] and reversible computing. He discovered, with Gilles Brassard, the concept of quantum cryptography and is one of the founding fathers of modern quantum information theory (cf. Bennett's four laws of quantum information).

Early career[edit]

Born in 1943 in New York City, Bennett earned a B.S. in Chemistry from Brandeis University in 1964, and received his PhD from Harvard in 1970 for molecular dynamics studies (computer simulation of molecular motion) under David Turnbull and Berni Alder. At Harvard, he also worked for James Watson one year as a teaching assistant about the genetic code. For the next two years he continued this research under the late Aneesur Rahman at Argonne Laboratory.

After joining IBM Research in 1972, he built on the work of IBM's Rolf Landauer to show that general-purpose computation can be performed by a logically and thermodynamically reversible apparatus; and in 1982 he proposed a re-interpretation of Maxwell's demon, attributing its inability to break the second law to the thermodynamic cost of destroying, rather than acquiring, information.[3] He also published an important paper on the estimation of free energy differences between two systems, the Bennett acceptance ratio method.

Quantum Cryptography[edit]

In collaboration with Gilles Brassard of the Université de Montréal he developed a system of quantum cryptography, known as BB84, which allows secure communication between parties who share no secret information initially, based on the uncertainty principle. With the help of John Smolin, he built the world's first working demonstration of quantum cryptography in 1989.

His other research interests include algorithmic information theory, in which the concepts of information and randomness are developed in terms of the input/output relation of universal computers, and the analogous use of universal computers to define the intrinsic complexity or "logical depth" of a physical state as the time required by a universal computer to simulate the evolution of the state from a random initial state.


In 1993 Bennett and Brassard, in collaboration with others, discovered "quantum teleportation", an effect in which the complete information in an unknown quantum state is decomposed into purely classical information and purely non-classical Einstein-Podolsky-Rosen (EPR paradox) correlations, sent through two separate channels, and later reassembled in a new location to produce an exact replica of the original quantum state that was destroyed in the sending process.

Later work[edit]

In 1995-7, working with Smolin, Wootters, IBM's Di Vincenzo, and other collaborators, he introduced several techniques for faithful transmission of classical and quantum information through noisy channels, part of the larger field of quantum information and computation theory. Together with others he also introduced the concept of entanglement distillation.

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[4] and the 2006 Rank Prize in opto-electronics.

Private life[edit]

On his religious views, Bennett is an atheist.[5]


  1. ^
  2. ^ Charles H. Bennett Bibliography
  3. ^ Bennett, C. H. (1982). "The thermodynamics of computation—a review". International Journal of Theoretical Physics. 21 (12): 905–940. doi:10.1007/BF02084158. 
  5. ^ "I am so sorry to hear of Asher's passing. I will miss his scientific insight and advice, but even more his humor and stuborn integrity. I remember when one of his colleagues complained about Asher's always rejecting his manuscript when they were sent to him to referee. Asher said in effect, "You should thank me. I am only trying to protect your reputation." He often pretended to consult me, a fellow atheist, on matters of religious protocol. As we waited in line to eat the hors d'oeuvres at a conference in Evanston, he said, "There is a prayer Jews traditionally say when they do something new that they have never done before. I am about to eat a new kind of non-Kosher food. Do you think I should say the prayer?" My wife and grown children, who are visiting us this new year, and remember Asher from when we all lived in Cambridge 20 years ago, join me in sending you our condolences for this sudden loss of an irrepressible and irreplaceable person. Please convey our feelings especially to your mother at this difficult time. " Charles H. Bennett's letter written to the family of Israeli physicist, Asher Peres, A selection of the many letters of condolence sent to the Peres family during January 2005 .

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