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We show that mixed states can produce maximal violations in the Bell inequality due to Clauser, Horne, Shimony, and Holt (CHSH). This follows from the degeneracy of the operator which is naturally associated with the Bell inequality (here called the Bell operator). We have calculated the form of all the eigenvalues for the generic CHSH Bell operator. Finally, we consider several examples which demonstrate the utility of studying the eigenvalues and eigenvectors of the Bell operator.
It is impossible to unambiguously distinguish the four Bell states in polarization, resorting to linear optical elements only. Recently, the hyperentangled Bell state, the simultaneous entanglement in more than one degree of freedom, has been used to assist in the complete Bell-state analysis of the four Bell states. However, if the additional degree of freedom is qubitlike, one can only distinguish 7 from the group of 16 states. Here we present a way to distinguish the hyperentangled Bell states completely with the help of cross-Kerr nonlinearity. Also, we discuss its application in the quantum teleportation of a particle in an unknown state in two different degrees of freedom and in the entanglement swapping of hyperentangled states. These applications will increase the channel capacity of long-distance quantum communication.
We discuss general Bell inequalities for bipartite and multipartite systems, emphasizing the connection with convex geometry on the mathematical side, and the communication aspects on the physical side. Known results on families of generalized Bell inequalities are summarized. We investigate maximal violations of Bell inequalities as well as states not violating (certain) Bell inequalities. Finally, we discuss the relation between Bell inequality violations and entanglement properties currently discussed in quantum information theory.
OBJECTIVE: To determine whether herpes simplex virus type 1 (HSV-1) causes Bell palsy. DESIGN: Prospective study. SETTING: University inpatient service. PATIENTS: 14 patients with Bell palsy, 9 patients with the Ramsay-Hunt syndrome, and 12 other controls. MEASUREMENTS: Viral genomes of HSV-1, varicella-zoster virus, and Epstein-Barr virus were analyzed in clinical samples of facial nerve endoneurial fluid and posterior auricular muscle using polymerase chain reaction (PCR) followed by hybridization with Southern blot analysis. RESULTS: Herpes simplex virus type 1 genomes were detected in 11 of 14 patients (79%) with Bell palsy but not in patients with the Ramsay-Hunt syndrome or in other controls. The nucleotide sequences of the PCR fragments were identical to those of the HSV-1 genome. CONCLUSIONS: Herpes simplex virus type 1 is the major etiologic agent in Bell palsy.
From its beginnings in the 1920s until its demise in the 1980s, Bell Labs - officially, the research and development wing of AT&T - was the biggest, and arguably the best, laboratory for new ideas in the world. From the transistor to the laser, from digital communications to cellular telephony, it's hard to find an aspect of modern life that hasn't been touched by Bell Labs. In The Idea Factory, Jon Gertner traces the origins of some of the twentieth century's most important inventions and delivers a riveting and heretofore untold chapter of American history. At its heart this is a story about the life and work of a small group of brilliant and eccentric men - Mervin Kelly, Bill Shockley, Claude Shannon, John Pierce, and Bill Baker - who spent their careers at Bell Labs. Today, when the drive to invent has become a mantra, Bell Labs offers us a way to enrich our understanding of the challenges and solutions to technological innovation. Here, after all, was where the foundational ideas on the management of innovation were born.
Although skeptical of the prohibitive power of no-hidden-variables theorems, John Bell was himself responsible for the two most important ones. I describe some recent versions of the lesser known of the two (familiar to experts as the "Kochen-Specker theorem") which have transparently simple proofs. One of the new versions can be converted without additional analysis into a powerful form of the very much better known "Bell's Theorem," thereby clarifying the conceptual link between these two results of Bell.
We report a quantum teleportation experiment in which nonlinear interactions are used for the Bell state measurements. The experimental results demonstrate the working principle of irreversibly teleporting an unknown arbitrary polarization state from one system to another distant system by disassembling into and then later reconstructing from purely classical information and nonclassical EPR correlations. The distinct feature of this experiment is that all four Bell states can be distinguished in the Bell state measurement. Teleportation of a polarization state can thus occur with certainty in principle.
Bell's 1964 theorem, which states that the predictions of quantum theory cannot be accounted for by any local theory, represents one of the most profound developments in the foundations of physics. In the last two decades, Bell's theorem has been a central theme of research from a variety of perspectives, mainly motivated by quantum information science, where the nonlocality of quantum theory underpins many of the advantages afforded by a quantum processing of information. The focus of this review is to a large extent oriented by these later developments. The main concepts and tools which have been developed to describe and study the nonlocality of quantum theory and which have raised this topic to the status of a full subfield of quantum information science are reviewed.
Using independent sources one can realize an ``event-ready'' Bell--Einstein-Podolsky-Rosen experiment in which one can measure directly the probabilities of the various outcomes including nondetection of both particles. Our proposal involves two parametric down-converters. Subcoherence-time monitoring of the idlers provides a noninteractive quantum measurement entangling and preselecting the independent signals without touching them. We give the conditions for high fringe visibility and particle collection efficiency as required for a Bell test.
Journal Article Ain't I a Woman: Black Women and Feminism, by Bell Hooks Get access Ain't I a Woman: Black Women and Feminism by Bell Hooks. Boston, Mass., South End Press, 1981. 205 pp. $7.00. Linda M. Perkins Linda M. Perkins The Mary Ingraham Bunting Institute, Radcliffe College Search for other works by this author on: Oxford Academic Google Scholar Political Science Quarterly, Volume 98, Issue 1, Spring 1983, Pages 145–146, https://doi.org/10.2307/2150228 Published: 15 March 1983
We develop a novel approach to Bell inequalities based on a constraint that the correlations exhibited by local variable theories must satisfy. This is used to construct a family of Bell inequalities for bipartite quantum systems of arbitrarily high dimensionality which are strongly resistant to noise. In particular, our work gives an analytic description of previous numerical results and generalizes them to arbitrarily high dimensionality.
In models of fermions coupled to gauge fields certain current-conservation laws are violated by Bell-Jackiw anomalies. In perturbation theory the total charge corresponding to such currents seems to be still conserved, but here it is shown that nonperturbative effects can give rise to interactions that violate the charge conservation. One consequence is baryon and lepton number nonconservation in $V\ensuremath{-}A$ gauge theories with charm. Another is the nonvanishing mass squared of the $\ensuremath{\eta}$.
In this paper we investigate the possibility of making complete Bell measurements on a product Hilbert space of two two-level bosonic systems. We restrict our tools to linear elements, such as beam splitters and phase shifters, delay lines and electronically switched linear elements, photodetectors, and auxiliary bosons. As a result we show that with these tools a never failing Bell measurement is impossible.
In a recent work [Phys. Rev. Lett. 98, 140402 (2007)] we defined ``steering,'' a type of quantum nonlocality that is logically distinct from both nonseparability and Bell nonlocality. In the bipartite setting, it hinges on the question of whether Alice can affect Bob's state at a distance through her choice of measurement. More precisely and operationally, it hinges on the question of whether Alice, with classical communication, can convince Bob that they share an entangled state under the circumstances that Bob trusts nothing that Alice says. We argue that if she can, then this demonstrates the nonlocal effect first identified in the famous Einstein-Podolsky-Rosen paper [Phys. Rev. 47, 777 (1935)] as a universal effect for pure entangled states. This ability of Alice to remotely prepare Bob's state was subsequently called steering by Schr\"odinger, whose terminology we adopt. The phenomenon of steering has been largely overlooked, and prior to our work had not even been given a rigorous definition that is applicable to mixed states as well as pure states. Armed with our rigorous definition, we proved that steerable states are a strict subset of the entangled states, and a strict superset of the states that can exhibit Bell nonlocality. In this work we expand on these results and provide further examples of steerable states. We also elaborate on the connection with the original EPR paradox.
We discuss a method for distinguishing the four orthogonal Bell states of two entangled particles. Because the scheme relies only on linear optical elements, it should be realizable with current technology. The new feature is that the Bell states must be embedded in a larger Hilbert space. That is, the correlated particles must be entangled in more than one degree of freedom.
More than two multipartite orthogonal states cannot always be discriminated if only local operations and classical communication (LOCC) are allowed. We show that four Bell states cannot be discriminated by LOCC, even probabilistically, using the separability properties of a four-party unlockable bound entangled state. Using an existing inequality among the measures of entanglement, we show that any three Bell states cannot be discriminated with certainty by LOCC. Exploiting the inequality, we calculate the distillable entanglement of a certain class of 4 multiply sign in circle 4 mixed states.
It is shown that the following statements about a quantum correlation experiment are mutually equivalent. (1) There is a deterministic hidden-variables model for the experiment. (2) There is a factorizable, stochastic model. (3) There is one joint distribution for all observables of the experiment, returning the experimental probabilities. (4) There are well-defined, compatible joint distributions for all pairs and triples of commuting and noncommuting observables. (5) The Bell inequalities hold.
A Franson-type test of Bell inequalities by photons 10.9 km apart is presented. Energy-time entangled photon pairs are measured using two-channel analyzers, leading to a violation of the inequalities by 16 standard deviations without subtracting accidental coincidences. Subtracting them, a two-photon interference visibility of $95.5%$ is observed, demonstrating that distances up to 10 km have no significant effect on entanglement. This sets quantum cryptography with photon pairs as a practical competitor to the schemes based on weak pulses.
The problem of tracking multiple objects in a video sequence poses several challenging tasks. For tracking-by-detection, these include object re-identification, motion prediction and dealing with occlusions. We present a tracker (without bells and whistles) that accomplishes tracking without specifically targeting any of these tasks, in particular, we perform no training or optimization on tracking data. To this end, we exploit the bounding box regression of an object detector to predict the position of an object in the next frame, thereby converting a detector into a Tracktor. We demonstrate the potential of Tracktor and provide a new state-of-the-art on three multi-object tracking benchmarks by extending it with a straightforward re-identification and camera motion compensation. We then perform an analysis on the performance and failure cases of several state-of-the-art tracking methods in comparison to our Tracktor. Surprisingly, none of the dedicated tracking methods are considerably better in dealing with complex tracking scenarios, namely, small and occluded objects or missing detections. However, our approach tackles most of the easy tracking scenarios. Therefore, we motivate our approach as a new tracking paradigm and point out promising future research directions. Overall, Tracktor yields superior tracking performance than any current tracking method and our analysis exposes remaining and unsolved tracking challenges to inspire future research directions.
Contents List of Illustrations List of Tables A Note to the Reader Preface Acknowledgments Introduction PART I. THE EMERGENCE OF A COGNITIVE ELITE 1 Cognitive Class and Education, 1900-1990 2 Cognitive Partitioning by Occupation 3 The Economic Pressure to Partition 4 Steeper Ladders, Narrower Gates PART II. COGNITIVE CLASSES AND SOCIAL BEHAVIOR 5 Poverty 6 Schooling 7 Unemployment, Idleness, and Injury 8 Family Matters 9 Welfare Dependency 10 Parenting 11 Crime 12 Civility and Citizenship PART III. THE NATIONAL CONTEXT 13 Ethnic Differences in Cognitive Ability 14 Ethnic Inequalities in Relation to IQ 15 The Demography of Intelligence 16 Social Behavior and the Prevalence of Low Cognitive Ability PART IV. LIVING TOGETHER 17 Raising Cognitive Ability 18 The Leveling of American Education 19 Affirmative Action in Higher Education 20 Affirmative Action in the Workplace 21 The Way We Are Headed 22 A Place for Everyone Afterworld APPENDIXES 1 Statistics for People Who Are Sure They Can't Learn Statistics 2 Technical Issues Regarding the National Longitudinal Survey of Youth 3 Technical Issues Regarding the Armed Forces Qualification Test as a Measure of IQ 4 Regression Analyses (rom Part II 5 Supplemental Material for Chapter 13 6 Regression Analyses from Chapter 14 7 The Evolution of Affirmative Action in the Workplace Notes Bibliography Index