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33
Testing the limits of quantum mechanics: motivation, state of play, prospects
, 2002
"... I present the motivation for experiments which attempt to generate, and verify the existence of, quantum superpositions of two or more states which are by some reasonable criterion ‘macroscopically’ distinct, and show that various a priori objections to this programme made in the literature are flaw ..."
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I present the motivation for experiments which attempt to generate, and verify the existence of, quantum superpositions of two or more states which are by some reasonable criterion ‘macroscopically’ distinct, and show that various a priori objections to this programme made in the literature are flawed. I review the extent to which such experiments currently exist in the areas of freespace molecular diffraction, magnetic biomolecules, quantum optics and Josephson devices, and sketch possible future lines of development of the programme.
Phase Retrieval via Matrix Completion
, 2011
"... This paper develops a novel framework for phase retrieval, a problem which arises in Xray crystallography, diffraction imaging, astronomical imaging and many other applications. Our approach, called PhaseLift, combines multiple structured illuminations together with ideas from convex programming to ..."
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This paper develops a novel framework for phase retrieval, a problem which arises in Xray crystallography, diffraction imaging, astronomical imaging and many other applications. Our approach, called PhaseLift, combines multiple structured illuminations together with ideas from convex programming to recover the phase from intensity measurements, typically from the modulus of the diffracted wave. We demonstrate empirically that any complexvalued object can be recovered from the knowledge of the magnitude of just a few diffracted patterns by solving a simple convex optimization problem inspired by the recent literature on matrix completion. More importantly, we also demonstrate that our noiseaware algorithms are stable in the sense that the reconstruction degrades gracefully as the signaltonoise ratio decreases. Finally, we introduce some theory showing that one can design very simple structured illumination patterns such that three diffracted figures uniquely determine the phase of the object we wish to recover.
The Content and Acquisition of Lexical Concepts
, 2006
"... This thesis aims to develop a psychologically plausible account of concepts by integrating key insights from philosophy (on the metaphysical basis for concept possession) and psychology (on the mechanisms underlying concept acquisition). I adopt an approach known as informational atomism, develope ..."
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This thesis aims to develop a psychologically plausible account of concepts by integrating key insights from philosophy (on the metaphysical basis for concept possession) and psychology (on the mechanisms underlying concept acquisition). I adopt an approach known as informational atomism, developed by Jerry Fodor. Informational atomism is the conjunction of two theses: (i) informational semantics, according to which conceptual content is constituted exhaustively by nomological mind–world relations; and (ii) conceptual atomism, according to which (lexical) concepts have no internal structure. I argue that informational semantics needs to be supplemented by allowing contentconstitutive rules of inference (“meaning postulates”). This is because the content of one important class of concepts, the logical terms, is not plausibly informational. And since, it is argued, no principled distinction can be drawn between logical concepts and the rest, the problem that this raises is a general one.
Is it true; or is it false; or somewhere in between? The logic of quantum theory. Contempory Phys
, 2005
"... The paper contains a relatively nontechnical summary of some recent work by the author and Jeremy Butterfield. The goal is to find a way of assigning meaningful truth values to propositions in quantum theory: something that is not possible in the normal, instrumentalist interpretation. The key math ..."
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The paper contains a relatively nontechnical summary of some recent work by the author and Jeremy Butterfield. The goal is to find a way of assigning meaningful truth values to propositions in quantum theory: something that is not possible in the normal, instrumentalist interpretation. The key mathematical tool is presheaf theory where, multivalued, contextual truth values arise naturally. We show how this can be applied to quantum theory, with the ‘contexts ’ chosen to be Boolean subalgebras of the set of all projection operators.
On Counterfactuals and Contextuality
 in AIP Conference Proceedings 750. Foundations of Probability and Physics3, edited by A. Khrennikov, American Institute of Physics
, 2005
"... Abstract. Counterfactual reasoning and contextuality is defined and critically evaluated with regard to its nonempirical content. To this end, a uniqueness property of states, explosion views and link observables are introduced. If only a single context associated with a particular maximum set of ob ..."
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Abstract. Counterfactual reasoning and contextuality is defined and critically evaluated with regard to its nonempirical content. To this end, a uniqueness property of states, explosion views and link observables are introduced. If only a single context associated with a particular maximum set of observables can be operationalized, then a context translation principle resolves measurements of different contexts. COUNTERFACTUALS With the rise of quantum mechanics [1, 2, 3, 4] physics proper entered an ancient and sometimes fierce debate in theology and philosophy: the controversy between realism versus idealism. Whereas realism has been subsumed by the proposition that [5] “some entities sometimes exist without being experienced by any finite mind, ” idealism put forward that “we have not the faintest reason for believing in the existence of unexperienced entities. [[Realism]] has been adopted... solely because it simplifies our view of the universe. ” And whereas these issues can be considered nonoperational and thus metaphysical or even ideological, it is also true that they have inspired a great number of minds, to the effect of stimulating new approaches to quantum mechanics, revealing many theoretical details, quantum phenomena and quantum technologies. The KochenSpecker theorem [6], for example, was motivated from the onset by scholasticism, as in an early programmatic article [7] Ernst Specker related the discussion on the foundations of quantum mechanics to scholastic
V.C. An Alternative Approach to Cross Impact Analysis
"... This paper presents the theoretical justification for the use of a particular analytical relation for calculating inferences from answers to cross impact questions. The similarity of the results to other types of analogous applications (i.e., logic regression, logistic models, and the FermiDirac di ..."
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This paper presents the theoretical justification for the use of a particular analytical relation for calculating inferences from answers to cross impact questions. The similarity of the results to other types of analogous applications (i.e., logic regression, logistic models, and the FermiDirac distribution) is indicated. An example of a cross impact analysis in an interactive computer mode is presented. Also discussed is the potential utilization of cross impact as: (1) A modeling tool for the analyst, (2) A consistency analysis tool for the decision maker, (3) A methodology for incorporating policy dependencies in large scale simulations, (4) A structured Delphi Conference for group analysis and discussion ' efforts and (S) A component of a lateral and adaptive management information system.
Criteria for continuousvariable quantum teleportation”, eprint quantph/9910030
, 1999
"... We derive an experimentally testable criterion for the teleportation of quantum states of continuous variables. This criterion is especially relevant to the recent experiment of Furusawa et al. [Science 282, 706 (1998)] where an inputoutput fidelity of 0.58 ± 0.02 was achieved for optical coherent ..."
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We derive an experimentally testable criterion for the teleportation of quantum states of continuous variables. This criterion is especially relevant to the recent experiment of Furusawa et al. [Science 282, 706 (1998)] where an inputoutput fidelity of 0.58 ± 0.02 was achieved for optical coherent states. Our derivation demonstrates that fidelities greater than 1/2 could not have been achieved through the use of a classical channel alone; quantum entanglement was a crucial ingredient in the experiment. 1
ScreeningOff and Causal Incompleteness: A NoGo Theorem
"... We begin by considering two principles, each having the form causal completeness ergo screeningoff. The first concerns a common cause of two or more effects; the second describes an intermediate link in a causal chain. They are logically independent of each other, each is independent of Reichenbach ..."
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We begin by considering two principles, each having the form causal completeness ergo screeningoff. The first concerns a common cause of two or more effects; the second describes an intermediate link in a causal chain. They are logically independent of each other, each is independent of Reichenbach’s principle of the common cause, and each is a consequence of the causal Markov condition. Simple examples show that causal incompleteness means that screeningoff may fail to obtain. We derive a stronger result: in a rather general setting, if the composite cause C 1 & C 2 &... & C n screensoff one event from another, then each of the n component causes C 1, C 2,..., C n must fail to screenoff. The idea that a cause may be ordinally invariant in its impact on different effects is defined; it plays an important role in establishing this nogo theorem. Along the way, we describe how composite and component causes can all screenoff when ordinal invariance fails. We argue that this theorem is relevant to assessing the plausibility of the two screeningoff principles. The discovery of incomplete causes that screenoff is not evidence that causal completeness must engender screeningoff. Formal and epistemic
Reasoning Formally about Quantum Systems: An Overview
, 2005
"... This article is intended as an introduction to the subject of quantum logic, and as a brief survey of the relevant literature. Also discussed here are logics for speci cation and analysis of quantum information systems, in particular, recent work by P. Mateus and A. Sernadas, and also by R. van der ..."
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This article is intended as an introduction to the subject of quantum logic, and as a brief survey of the relevant literature. Also discussed here are logics for speci cation and analysis of quantum information systems, in particular, recent work by P. Mateus and A. Sernadas, and also by R. van der Meyden and M. Patra. Overall, our objective is to provide a highlevel presentation of the logical aspects of quantum theory. Mateus ' and Sernadas ' EQPL logic is illustrated with a small example, namely the state of an entangled pair of qubits. The &quot;KT&quot; logic of van der Meyden and Patra is demonstrated brie y in the context of the B92 protocol for quantum key distribution. 1
The axiomatic method in the empirical sciences
 Proceedings of the Tarski Symposium, Proceedings of Symposia in Pure Mathematics Volume XXV
, 1974
"... l. Introduction. My original intention was to give a talk primarily on the theory of models as applied to the theory of measurement in the empirical sciences. Conversations with Tarski earlier in the symposium changed my mind. We agreed that it would be desirable to have a survey, even if superficia ..."
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l. Introduction. My original intention was to give a talk primarily on the theory of models as applied to the theory of measurement in the empirical sciences. Conversations with Tarski earlier in the symposium changed my mind. We agreed that it would be desirable to have a survey, even if superficial, of the place of the axiomatic method and the theory of models in the empirical sciences. And so my