Topic
Coherent information
About: Coherent information is a research topic. Over the lifetime, 1225 publications have been published within this topic receiving 46672 citations.
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TL;DR: In this paper, it was shown that the contribution of spins greater than 1/2 to the entropy is not negligible, and the value of the Barbero-Immirzi parameter involved in the spectra of all the geometric and physical operators in this theory is different than previously derived.
Abstract: Quantum geometry (the modern loop quantum gravity involving graphs and spin-networks instead of the loops) provides microscopic degrees of freedom that account for black-hole entropy. However, the procedure for state counting used in the literature contains an error and the number of the relevant horizon states is underestimated. In our paper a correct method of counting is presented. Our results lead to a revision of the literature of the subject. It turns out that the contribution of spins greater than 1/2 to the entropy is not negligible. Hence, the value of the Barbero–Immirzi parameter involved in the spectra of all the geometric and physical operators in this theory is different than previously derived. Also, the conjectured relation between quantum geometry and the black-hole quasi-normal modes should be understood again.
440 citations
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TL;DR: In this article, a multiparty quantum state sharing scheme for an arbitrary two-particle state is presented with Einstein-Podolsky-Rosen pairs, where any one of the agents has the access to regenerate the original state with two local unitary operations if he collaborates with the other agents, say the controllers.
Abstract: A scheme for multiparty quantum state sharing of an arbitrary two-particle state is presented with Einstein-Podolsky-Rosen pairs. Any one of the $N$ agents has the access to regenerate the original state with two local unitary operations if he collaborates with the other agents, say the controllers. Moreover, each of the controllers is required to take only a product measurement ${\ensuremath{\sigma}}_{x}\ensuremath{\bigotimes}{\ensuremath{\sigma}}_{x}$ on his two particles, which makes this scheme more convenient for the agents in the applications on a network than others. As all the quantum source can be used to carry the useful information, the intrinsic efficiency of qubits approaches the maximal value. With a new notation for the multipartite entanglement, the sender need only publish two bits of classical information for each measurement, which reduces the information exchanged largely.
436 citations
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TL;DR: It is shown that different applications may result in different channel capacities, and upper bounds on several of these capacities are proved based on the coherent information, which plays a role in quantum information theory analogous to that played by the mutual information in classical information theory.
Abstract: Noisy quantum channels may be used in many information-carrying applications. We show that different applications may result in different channel capacities. Upper bounds on several of these capacities are proved. These bounds are based on the coherent information, which plays a role in quantum information theory analogous to that played by the mutual information in classical information theory. Many new properties of the coherent information and entanglement fidelity are proved. Two nonclassical features of the coherent information are demonstrated: the failure of subadditivity, and the failure of the pipelining inequality. Both properties arise as a consequence of quantum entanglement, and give quantum information new features not found in classical information theory. The problem of a noisy quantum channel with a classical observer measuring the environment is introduced, and bounds on the corresponding channel capacity proved. These bounds are always greater than for the unobserved channel. We conclude with a summary of open problems.
409 citations
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TL;DR: In addition to the scheduled program, the following two papers, by A. N. Kolmogorov and V. I. Siforov, were presented at the 1956 Symposium on Information Theory.
Abstract: In addition to the scheduled program, the following two papers, by A. N. Kolmogorov and V. I. Siforov, were presented at the 1956 Symposium on Information Theory. However, the manuscripts were received too late for inclusion in the September (Symposium) issue of these TRANSACTIONS. The papers were submitted in response to our invitation to these distinguished Russian scientists, and the following translations were distributed to those attending the Symposium.--The Editor.
395 citations
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TL;DR: It is shown how to compute or at least to estimate various capacity-related quantities for bosonic Gaussian channels, including the coherent information, the entanglement-assisted classical capacity, the one-shot classical capacity and a quantity involving the transpose operation, shown to be a general upper bound on the quantum capacity.
Abstract: We show how to compute or at least to estimate various capacity-related quantities for Bosonic Gaussian channels. Among these are the coherent information, the entanglement assisted classical capacity, the one-shot classical capacity, and a new quantity involving the transpose operation, shown to be a general upper bound on the quantum capacity, even allowing for finite errors. All bounds are explicitly evaluated for the case of a one-mode channel with attenuation/amplification and classical noise.
358 citations