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 article, an analytical expression for the coherent information of the thermal radiation signal transmitted over a thermal radiation noise channel, one of the most essential quantum Gaussian channels, is given.
Abstract: An analytical expression is given to the coherent information of the thermal radiation signal transmitted over the thermal radiation noise channel, one of the most essential quantum Gaussian channels. Focusing on the single normal mode of the thermal radiation signal and noise, we resolve the entangled state density operator, which characterizes quantum information transmission, into a direct product of two parts, with each part being a thermal radiation density operator. The calculation is aided by the technique known as ``integral within ordered product of operators".
7 citations
TL;DR: In this paper, the authors describe general results about information flow between interacting systems, which can be expressed in diagrammatic form, and remark that one simple type of two-qubit interaction, the unitary CNOT gate, cannot be represented by local operations and a single simultaneous information exchange.
Abstract: From the structure of quantum dynamics for closed and open systems, we describe several general results about information flow between interacting systems, which can be expressed in diagrammatic form. Conditions on information flow (e.g., that no information is transferred from system A to system B) imply that the overall dynamical evolution has a particular structure. We also remark that one simple type of two-qubit interaction, the unitary CNOT gate, cannot be represented by local operations and a single simultaneous information exchange.
7 citations
TL;DR: It is shown that the use of phase coherent states gives better performance in terms of noise tolerance, key rate, and achievable distance than that of common linear coherent states.
Abstract: In this paper, we present three continuous variable quantum key distribution protocols (named two-, four-, and eight-state protocols) based on the discrete modulation of phase coherent states. We investigate the security of these protocols against the collective eavesdropping attacks and show their performance in a realistic setup by taking into consideration the realistic lossy noisy quantum channels, and the imperfection of detection. We show that the use of phase coherent states gives better performance in terms of noise tolerance, key rate, and achievable distance than that of common linear coherent states.
7 citations
TL;DR: The quantum formalism would appear from this comparative analysis between QIB and DAQM as an optimal information scheme that would maximise the stability of biological and physical systems at any scale.
Abstract: The similarities between biological and physical systems as respectively defined in quantum information biology (QIB) and in a Darwinian approach to quantum mechanics (DAQM) have been analysed. In both theories the processing of information is a central feature characterising the systems. The analysis highlights a mutual support on the thesis contended by each theory. On the one hand, DAQM provides a physical basis that might explain the key role played by quantum information at the macroscopic level for bio-systems in QIB. On the other hand, QIB offers the possibility, acting as a macroscopic testing ground, to analyse the emergence of quantumness from classicality in the terms held by DAQM. As an added result of the comparison, a tentative definition of quantum information in terms of classical information flows has been proposed. The quantum formalism would appear from this comparative analysis between QIB and DAQM as an optimal information scheme that would maximise the stability of biological and physical systems at any scale.
7 citations
TL;DR: Basic theoretical and experimental results proving the possibility of coherent manipulations with phonon states of NEMSs, their cooling to the ground vibrational state, and organization of controllable interaction between them and other quantum information carriers are presented.
Abstract: Application of nanoelectromechanical systems (NEMSs) as one of the structural components of quantum computers assumes a high level of coherent control of their state. In this case, such objects could perform certain functions in the coding, storing, and transportation of quantum information, and serve as auxiliary elements for processing such information. This paper contains a survey of basic theoretical and experimental results proving the possibility of coherent manipulations with phonon states of NEMSs, their cooling to the ground vibrational state, and organization of controllable interaction between them and other quantum information carriers.
7 citations