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Showing papers on "Coherent information published in 1993"


Journal ArticleDOI
TL;DR: The possible amount of information transfer between any source and any user via a quantum system is bounded through the quantum entropy function, which shows that infinite information transfer implies infinite entropy.
Abstract: The possible amount of information transfer between any source and any user via a quantum system is bounded through the quantum entropy function. In contrast to the classical case, this shows that infinite information transfer implies infinite entropy. The entropy bound is also applied to obtain the ultimate quantum information transmission capacity of the free electromagnetic field under a power and a bandwidth constraint.

179 citations


Journal ArticleDOI
TL;DR: The Landauer cost for erasing information demands that information about a physical system be included in the total entropy, as proposed by Zurek, and this must imply that work can be extracted in going from equilibrium to a typical system state.
Abstract: The Landauer cost for erasing information demands that information about a physical system be included in the total entropy, as proposed by Zurek [Nature 341, 119 (1989); Phys. Rev. A 40, 4731 (1989)]. A consequence is that most system states-either classical phase-space distributions or quantum pure states-have total entropy much larger than thermal equilibrium. If total entropy is to be a useful concept, this must imply that work can be extracted in going from equilibrium to a typical system state. The work comes from randomization of a «memory» that holds a record of the system state

58 citations


Journal ArticleDOI
TL;DR: Information theory is used to assess the effect of speckle on the information content of coherent images and particular emphasis is given to relating information theoretic concepts to intuitive descriptions of information based on physical models.
Abstract: Information theory, as developed by Shannon (1948), provides a theoretical framework for describing the transfer of information through a communication channel. A coherent imaging system is a particular form of communication channel which is characterized by a multiplicative noise process termed 'speckle'. Information theory is used to assess the effect of speckle on the information content of coherent images. Particular emphasis is given to relating information theoretic concepts to intuitive descriptions of information based on physical models.

17 citations


Journal ArticleDOI
TL;DR: In this article, the Bargmann representation corresponding to these states involves both the standard integral with respect to the Gaussian measure and the Berezin integral over Grassmann variables, and the quantum generalizations of many constructions developed for classical coherent states are described.
Abstract: The coherent states for the quantum complex plane are introduced. It is demonstrated that the Bargmann representation corresponding to these states involves both the standard integral with respect to the Gaussian measure and the Berezin integral over Grassmann variables. The quantum generalizations of many constructions developed for classical coherent states are described.

14 citations


Journal ArticleDOI
TL;DR: A quantitative information theory is developed for both classical and quantum spin systems and gives an explanation to the surprising result that the capacity per bit can be greater than one.
Abstract: A quantitative information theory is developed for both classical and quantum spin systems. The theory is examined by heavy numerical simulations, which show that the information embedded in each weight of the system increases with the size of the system. The difference between the notions of capacity and information is examined carefully and gives an explanation to the surprising result that the capacity per bit can be greater than one.