Papers by Charles Bennett
MRS Proceedings, 1991
In order to improve our ability to simulate the complex behavior of polymers, we introduce dynami... more In order to improve our ability to simulate the complex behavior of polymers, we introduce dynamical models in the class of Cellular Automata (CA). Space partitioning methods enable us to overcome fundamental obstacles to large scale simulation of connected chains with excluded volume by parallel processing computers. A highly efficient, two-space algorithm is devised and tested on both Cellular Automata Machines (CAMs) and serial computers. Preliminary results on the static and dynamic properties of polymers in two dimensions are reported.
arXiv (Cornell University), Aug 18, 2003
We describe a collection of techniques whereby audiovisual or other recordings of significant eve... more We describe a collection of techniques whereby audiovisual or other recordings of significant events can be made in a way that hinders falsification, pre-dating, or postdating by interested parties, even by the makers and operators of the recording equipment. A central feature of these techniques is the interplay between private information, which by its nature is untrustworthy and susceptible to suppression or manipulation by interested parties, and public information, which is too widely known to be manipulated by anyone. While authenticated recordings may be infeasible to falsify, they can be abused in other ways, such as being used for blackmail or harassment; but susceptibility to these abuses can be reduced by encryption and secret sharing.
Nontrivial, "complex" or " organized" states of a physical system may be characterized as those i... more Nontrivial, "complex" or " organized" states of a physical system may be characterized as those implausible save as the result of a long causal history or evolution. This notion, formalized by the tools of the theory of universal digital computers, is compared to other notions of complexity, and an attempt is made to sketch open problems in the computation theory and statistical physics whose resolution would lead to a better fundamental understanding of "self-organization" in the universe.
arXiv (Cornell University), Mar 29, 2013
Superlattices and Microstructures, 1998
Landauer's contributions to the physics of information transmission and processing are highlighte... more Landauer's contributions to the physics of information transmission and processing are highlighted by figures and cartoons drawn by himself and others
Science, 2004
I will give an overview on the current state of knowledge on communication via quantum channels. ... more I will give an overview on the current state of knowledge on communication via quantum channels. In this subject, the fundamental question is that of the capacity of a given channel, when used in a memoryless fashion asymptotically many times. It is well-known nowadays that quantum channels, unlike their classical counterparts, are not characterized by a single capacity number, but instead give rise to a veritable "zoo" of capacities. My intention in this tutorial is to describe recent progress and major challenges in the theory of quantum channel capacities, using roughly two thirds of the allotted time; in the remaining third I will take questions from the audience on the broad topic of the tutorial, and answer them on the board.
Physical Review Letters, 1985
Physical Review Letters, 1993
The analogy between temporally periodic phases of noisy extended driven systems and smooth interf... more The analogy between temporally periodic phases of noisy extended driven systems and smooth interfaces in growth models is used to derive results for both problems, viz. , stable, temporally quasiperiodic phases with long-range spatial order can in fact occur for noisy, short-range, isotropic rules in dimensions d & 2. For d=2, temporally quasiperiodic phases have algebraic, rather than long-range, order, and occur only in anisotropic systems. Anisotropic rules can also produce smooth, commensurately growing interfaces with d) 2 dimensions for generic parameter values.
Nature, 1991
Lakes Victoria and Malawi as well as to Astatoreochromis alluaudi. The results confirm (with 97 p... more Lakes Victoria and Malawi as well as to Astatoreochromis alluaudi. The results confirm (with 97 per cent confidence) the hypothesis, suggested by interspecific hybridization studies, that A. burtoni is a closer relative of these flocks than is Astatoreochromis. This analysis also suggests (although not significant statistically) that A. burtoni is closer phylogenetically to the Lake Victoria flock than is the Lake Malawi flock. Furthermore, and contrary to the hypothesis of Crapon de Caprona and Fritzsch above, the members of the Lake Victoria flock (including A. nubilis, A. elegansandA. piceatus are more closely related to one another mitochondrially than to A. burtoni. The bootstrap value that shows the reality of the a-b lineage in the figure is 100 per cent. We infer that the Lake Victoria flock arose long after the splitting of the A. burtoni lineage from the a-b lineage. Our molecular estimate of the time of most recent common ancestry for the Lake Victoria flock is 200,000 years 1 , which implies that the flock is younger than the lake (250,000 to 7 50,000 years old 6). Thus, our results cast doubt on Crapon de Caprona and Fritzsch's model, above, according to which segregation occurred within the flock before the lake formed. Another notable feature of the figure is
Journal of Computational Physics, 1976
Near-optimal strategies are developed for estimating the free energy difference between two canon... more Near-optimal strategies are developed for estimating the free energy difference between two canonical ensembles, given a Metropolis-type Monte Carlo program for sampling each one. The estimation strategy depends on the extent of overlap between the two ensembles, on the smoothness of the density-of-states as a function of the difference potential, and on the relative Monte Carlo sampling costs, per statistically independent data point. The best estimate of the free energy difference is usually obtained by dividing the available computer time approximately equally between the two ensembles; its efficiency (variance x computer time)-' is never less, and may be several orders of magnitude greater, than that obtained by sampling only one ensemble, as is done in perturbation theory.
arXiv (Cornell University), Oct 1, 2002
The first essay discusses, in nontechnical terms, the paradox implicit in defining a random integ... more The first essay discusses, in nontechnical terms, the paradox implicit in defining a random integer as one without remarkable properties, and the resolution of that paradox at the cost of making randomness a property which most integers have but can’t be proved to have. The second essay briefly reviews the search for randomness in the digit sequences of natural irrational numbers like π and artificial ones like Champernowne’s C = 0.12345678910111213 . . ., and discusses at length Chaitin’s definable-but-uncomputable number Ω, whose digit sequence is so random that no betting strategy could succeed against it. Other, Cabalistic properties of Ω are pointed out for the first time.
IEEE Transactions on Information Theory, Aug 1, 2003
We consider interactions as bidirectional channels. We investigate the capacities for interaction... more We consider interactions as bidirectional channels. We investigate the capacities for interaction Hamiltonians and nonlocal unitary gates to generate entanglement and transmit classical information. We give analytic expressions for the entanglement generating capacity and entanglement-assisted one-way classical communication capacity of interactions, and show that these quantities are additive, so that the asymptotic capacities equal the corresponding 1-shot capacities. We give general bounds on other capacities, discuss some examples, and conclude with some open questions.
Physical Review Letters, Feb 15, 2002
Physical Review Letters, Mar 10, 1997
Two separated observers, by applying local operations to a supply of not-too-impure entangled sta... more Two separated observers, by applying local operations to a supply of not-too-impure entangled states (e.g. singlets shared through a noisy channel), can prepare a smaller number of entangled pairs of arbitrarily high purity (e.g. nearperfect singlets). These can then be used to faithfully teleport unknown quantum states from one observer to the other, thereby achieving faithful transmission of quantum information through a noisy channel. We give upper and lower bounds on the yield D(M) of pure singlets (|Ψ −) distillable from mixed states M , showing D(M) > 0 if Ψ − |M |Ψ − > 1 2 .
Physical Review Letters, Jul 26, 2001
Quantum teleportation uses prior entanglement and forward classical communication to transmit one... more Quantum teleportation uses prior entanglement and forward classical communication to transmit one instance of an unknown quantum state. Remote state preparation (RSP) has the same goal, but the sender knows classically what state is to be transmitted. We show that the asymptotic classical communication cost of RSP is one bit per qubit-half that of teleportation-and even less when transmitting part of a known entangled state. We explore the tradeoff between entanglement and classical communication required for RSP, and discuss RSP capacities of general quantum channels.
Physical Review Letters, Mar 10, 1997
IEEE Transactions on Information Theory, May 1, 2014
Dual to the usual noisy channel coding problem, where a noisy (classical or quantum) channel is u... more Dual to the usual noisy channel coding problem, where a noisy (classical or quantum) channel is used to simulate a noiseless one, reverse Shannon theorems concern the use of noiseless channels to simulate noisy ones, and more generally the use of one noisy channel to simulate another. For channels of nonzero capacity, this simulation is always possible, but for it to be efficient, auxiliary resources of the proper kind and amount are generally required. In the classical case, shared randomness between sender and receiver is a sufficient auxiliary resource, regardless of the nature of the source, but in the quantum case the requisite auxiliary resources for efficient simulation depend on both the channel being simulated, and the source from which the channel inputs are coming. For tensor power sources (the quantum generalization of classical IID sources), entanglement in the form of standard ebits (maximally entangled pairs of qubits) is sufficient, but for general sources, which may be arbitrarily correlated or entangled across channel inputs, additional resources, such as entanglement-embezzling states or backward communication, are generally needed. Combining existing and new results, we establish the amounts of communication and auxiliary resources needed in both the classical and quantum cases, the tradeoffs among them, and the loss of simulation efficiency when auxiliary resources are absent or insufficient. In particular we find a new single-letter expression for the excess forward communication cost of coherent feedback simulations of quantum channels (i.e. simulations in which the sender retains what would escape into the environment in an ordinary simulation), on nontensor-power sources in the presence of unlimited ebits but no other auxiliary resource. Our results on tensor power sources establish a strong converse to the entanglement-assisted capacity theorem.
arXiv (Cornell University), Jun 17, 2010
While Kolmogorov complexity is the accepted absolute measure of information content in an individ... more While Kolmogorov complexity is the accepted absolute measure of information content in an individual finite object, a similarly absolute notion is needed for the information distance between two individual objects, for example, two pictures. We give several natural definitions of a universal information metric, based on length of shortest programs for either ordinary computations or reversible (dissipationless) computations. It turns out that these definitions are equivalent up to an additive logarithmic term. We show that the information distance is a universal cognitive similarity distance. We investigate the maximal correlation of the shortest programs involved, the maximal uncorrelation of programs (a generalization of the Slepian-Wolf theorem of classical information theory), and the density properties of the discrete metric spaces induced by the information distances. A related distance measures the amount of nonreversibility of a computation. Using the physical theory of reversible computation, we give an appropriate (universal, anti-symmetric, and transitive) measure of the
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Papers by Charles Bennett