11,119 research outputs found

    Comment on "Groverian Entanglement Measure and Evolution of Entanglement in Search Algorithm for n(= 3, 5)-Qubit Systems with Real Coefficients" (Volume 6, Number 4, August 2007), by Arti Chamoli and C. M. Bhandari

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    We point out that the main results-the analytic expressions for the Groverian Measure of Entanglement, in the above mentioned paper are erroneous. The technical mistake of the paper is discussed. It is shown by an explicit example that the formula for calculating the Groverian measure yields G(|\psi>) = 0 for some entangled states.Comment: 4 pages, published online in Quantum Info. Process. on 24 July 200

    Fluctuation theorems in presence of information gain and feedback

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    In this study, we rederive the fluctuation theorems in presence of feedback, by assuming the known Jarzynski equality and detailed fluctuation theorems. We first reproduce the already known work theorems for a classical system, and then extend the treatment to the other classical theorems. For deriving the extended quantum fluctuation theorems, we have considered open systems. No assumption is made on the nature of environment and the strength of system-bath coupling. However, it is assumed that the measurement process involves classical errors.Comment: 8 pages, 1 figur

    The emotional valence of subliminal priming effects perception of facial expressions

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    We investigated, in young healthy subjects, how the affective content of subliminally presented priming images and their specific visual attributes impacted conscious perception of facial expressions. The priming images were broadly categorised as aggressive, pleasant, or neutral and further subcategorised by the presence of a face and by the centricity (egocentric or allocentric vantage-point) of the image content. Subjects responded to the emotion portrayed in a pixelated target-face by indicating via key-press if the expression was angry or neutral. Priming images containing a face compared to those not containing a face significantly impaired performance on neutral or angry targetface evaluation. Recognition of angry target-face expressions was selectively impaired by pleasant prime images which contained a face. For egocentric primes, recognition of neutral target-face expressions was significantly better than of angry expressions. Our results suggest that, first, the affective primacy hypothesis which predicts that affective information can be accessed automatically, preceding conscious cognition, holds true in subliminal priming only when the priming image contains a face. Second, egocentric primes interfere with the perception of angry target-face expressions suggesting that this vantage-point, directly relevant to the viewer, perhaps engages processes involved in action preparation which may weaken the priority of affect processing.Accepted manuscrip

    Entanglement and coherence in quantum state merging

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    Understanding the resource consumption in distributed scenarios is one of the main goals of quantum information theory. A prominent example for such a scenario is the task of quantum state merging where two parties aim to merge their parts of a tripartite quantum state. In standard quantum state merging, entanglement is considered as an expensive resource, while local quantum operations can be performed at no additional cost. However, recent developments show that some local operations could be more expensive than others: it is reasonable to distinguish between local incoherent operations and local operations which can create coherence. This idea leads us to the task of incoherent quantum state merging, where one of the parties has free access to local incoherent operations only. In this case the resources of the process are quantified by pairs of entanglement and coherence. Here, we develop tools for studying this process, and apply them to several relevant scenarios. While quantum state merging can lead to a gain of entanglement, our results imply that no merging procedure can gain entanglement and coherence at the same time. We also provide a general lower bound on the entanglement-coherence sum, and show that the bound is tight for all pure states. Our results also lead to an incoherent version of Schumacher compression: in this case the compression rate is equal to the von Neumann entropy of the diagonal elements of the corresponding quantum state.Comment: 9 pages, 1 figure. Lemma 5 in Appendix D of the previous version was not correct. This did not affect the results of the main tex

    Estimating the Production Potential of Major Crops in Pakistan’s Irrigated Agriculture during the 21st Century

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    Land and irrigation are the basic resources in agriculture. The role and importance of these resources and their contribution towards productivity, in the context of the country’s increasing population, can hardly be exaggerated. Pakistani agriculture is set in a very distinctive situation of an increasing population on the one hand and diminishing resources on the other. The population of Pakistan was reported to be 131.63 million in 1996 and is projected to be 207 million in 2013 [Pakistan (1996) and WSIP (1990)]. The agriculture sector has to face the difficult task of doubling the existing food production by the turn of this century. The situation demands horizontal and vertical growth in the productivity, either by bringing more land under cultivation, or by increasing the cropping intensity of the existing land resources. This can also be accomplished by bringing more land under cultivation from the cultivable uncultivated area (a large proportion of which exists on medium and large farms under waterlogged or saline conditions). In this context, it becomes important to identify the nature of the relationship that exists between farm size and unculturable wastelands and the kinds of changes the green revolution/SCARPs projects introduced to this relationship.
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