782 research outputs found

    Quantum-gate implementation in permanently coupled AF spin rings without need of local fields

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    We propose a scheme for the implementation of quantum gates which is based on the qubit encoding in antiferromagnetic molecular rings. We show that a proper engineering of the intercluster link would result in an effective coupling that vanishes as far as the system is kept in the computational space, while it is turned on by a selective excitation of specific auxiliary states. These are also shown to allow the performing of single- and two-qubit gates without an individual addressing of the rings by means of local magnetic fields.Comment: To appear in Physical Review Letter

    End-to-End Entanglement Generation Strategies: Capacity Bounds and Impact on Quantum Key Distribution

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    A first quantum revolution has already brought quantum technologies into our everyday life for decades: in fact, electronics and optics are based on the quantum mechanical principles. Today, a second quantum revolution is underway, leveraging the quantum principles of superposition, entanglement and measurement, which were not fully exploited yet. International innovation activities and standardization bodies have identified four main application areas for quantum technologies and services: quantum secure communications, quantum computing, quantum simulation, and quantum sensing and metrology. This paper focuses on quantum secure communications by addressing the evolution of Quantum Key Distribution (QKD) networks (under early exploitation today) towards the Quantum-ready networks and the Quantum Internet based also on entanglement distribution. Assuming that management and control of quantum nodes is a key challenge under definition, today, a main obstacle in exploiting long-range QKD and Quantum-ready networks concerns the inherent losses due to the optical transmission channels. Currently, it is assumed that a most promising way for overcoming this limitation, while avoiding the presence of costly trusted nodes, it is to distribute entangled states by means of Quantum Repeaters. In this respect, the paper provides an overview of current methods and systems for end-to-end entanglement generation, with some simulations and a discussion of capacity upper bounds and their impact of secret key rate in QKD systems

    Harm shouldn\u2019t be a necessary criterion for mental disorder: Some reflections on the DSM-5 definition of mental disorder

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    The general definition of mental disorder stated in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders seems to identify a mental disorder with a harmful dysfunction. However, the presence of distress or disability, which may be bracketed as the presence of harm, is taken to be merely usual, and thus not a necessary requirement: a mental disorder can be diagnosed as such even if there is no harm at all. In this paper, we focus on the harm requirement. First, we clarify what it means to say that the harm requirement is not necessary for defining the general concept of mental disorder. In this respect, we briefly examine the two components of harm, distress and disability, and then trace a distinction between mental disorder tokens and mental disorder types. Second, we argue that the decision not to regard the harm requirement as a necessary criterion for mental disorder is tenable for a number of practical and theoretical reasons, some pertaining to conceptual issues surrounding the two components of harm and others pertaining to the problem of false negatives and the status of psychiatry vis-\ue0-vis somatic medicine. However, we believe that the harm requirement can be (provisionally) maintained among the specific diagnostic criteria of certain individual mental disorders. More precisely, we argue that insofar as the harm requirement is needed among the specific diagnostic criteria of certain individual mental disorders, it should be unpacked and clarified

    New Trends in Philosophy of Mind and Epistemology: An Overview

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    open2openM.C. Amoretti; F. ErvasAmoretti, MARIA CRISTINA; F., Erva

    The concept of disease in the time of COVID-19

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    Philosophers of medicine have formulated different accounts of the concept of disease. Which concept of disease one assumes has implications for what conditions count as diseases and, by extension, who may be regarded as having a disease (disease judgements) and for who may be accorded the social privileges and personal responsibilities associated with being sick (sickness judgements). In this article, we consider an ideal diagnostic test for coronavirus disease 2019 (COVID-19) infection with respect to four groups of people—positive and asymptomatic; positive and symptomatic; negative; and untested—and show how different concepts of disease impact on the disease and sickness judgements for these groups. The suggestion is that sickness judgements and social measures akin to those experienced during the current COVID-19 outbreak presuppose a concept of disease containing social (risk of) harm as a component. We indicate the problems that arise when adopting this kind of disease concept beyond a state of emergency

    Unveiling the interplay between evidence, values and cognitive biases. The case of the failure of the AstraZeneca COVID-19 vaccine

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    This paper depicts a Covid science case, that of the AstraZeneca Vaxzevria vaccine, with specific focus on what happened in Italy. Given that we believe acknowledging the role of non-evidential factors in medicine is an important insight into the recent philosophy of science, we illustrate how in the case of Vaxzevria, the interplay between facts, values (both epistemic and non-epistemic) and cognitive biases may have possibly led to different institutional decisions based on the same evidence. The structure of the paper is as follows. First, we provide a glossary of the relevant terms involved, that is to say, epistemic values, non-epistemic values and cognitive biases. Second, we sketch a timeline of Vaxzevria's approvals and suspensions by relevant institutional healthcare authorities with special focus on Italy and the Italian Medicines Agency. Then we show the interplay between the evidence base, epistemic as well as non-epistemic values and cognitive biases using a narrative review of political decisions along with newspaper and social media content pertaining to Vaxzevria. We briefly compare Italy with other European countries to show that different political decisions were made on the basis of the same evidence

    On the non-relativistic limit of charge conjugation in QED

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    Even if at the level of the non-relativistic limit of full QED, C is not a symmetry, the limit of this operation does exist for the particular case when the electromagnetic field is considered a classical external object coupled to the Dirac field. This result extends the one obtained when fermions are described by the Schroedinger-Pauli equation. We give the expressions for both the C matrix and the C^\hat{C} operator for galilean electrons and positrons interacting with the external electromagnetic field. The result is relevant in relation to recent experiments with antihydrogen.Comment: 7 page

    The First Cold Antihydrogen

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    Antihydrogen, the atomic bound state of an antiproton and a positron, was produced at low energy for the first time by the ATHENA experiment, marking an important first step for precision studies of atomic antimatter. This paper describes the first production and some subsequent developments.Comment: Invitated Talk at COOL03, International Workshop on Beam Cooling and Related Topics, to be published in NIM

    The Notion of Gender in Psychiatry: A Focus on DSM-5

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    In this paper I review how the notion of gender is understood in psychiatry, specifically in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). First, I examine the contraposition between sex and gender, and argue that it is still retained by DSM-5, even though with some caveats. Second, I claim that, even if genderqueer people are not pathologized and gender pluralism is the background assumption, some diagnostic criteria still conceal a residue of gender dualism and essentialism. Third, I consider gender dysphoria, which is characterized by an incongruence between one’s experienced or expressed gender and one’s assigned gender; since this condition pertains to distress and disability, not to the incongruence per se, it does not pathologize transgender people. Still, I contend that it should be removed from DSM-5 for theoretical reasons
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