18,007 research outputs found

    Dynamically localized systems: entanglement exponential sensitivity and efficient quantum simulations

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    We study the pairwise entanglement present in a quantum computer that simulates a dynamically localized system. We show that the concurrence is exponentially sensitive to changes in the Hamiltonian of the simulated system. Moreover, concurrence is exponentially sensitive to the ``logic'' position of the qubits chosen. These sensitivities could be experimentally checked efficiently by means of quantum simulations with less than ten qubits. We also show that the feasibility of efficient quantum simulations is deeply connected to the dynamical regime of the simulated system.Comment: 5 pages, 6 figure

    Infinite index extensions of local nets and defects

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    Subfactor theory provides a tool to analyze and construct extensions of Quantum Field Theories, once the latter are formulated as local nets of von Neumann algebras. We generalize some of the results of [LR95] to the case of extensions with infinite Jones index. This case naturally arises in physics, the canonical examples are given by global gauge theories with respect to a compact (non-finite) group of internal symmetries. Building on the works of Izumi, Longo, Popa [ILP98] and Fidaleo, Isola [FI99], we consider generalized Q-systems (of intertwiners) for a semidiscrete inclusion of properly infinite von Neumann algebras, which generalize ordinary Q-systems introduced by Longo [Lon94] to the infinite index case. We characterize inclusions which admit generalized Q-systems of intertwiners and define a braided product among the latter, hence we construct examples of QFTs with defects (phase boundaries) of infinite index, extending the family of boundaries in the grasp of [BKLR16].Comment: 50 page

    Hamiltonian analysis of subcritical stochastic epidemic dynamics

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    We extend a technique of approximation of the long-term behavior of a supercritical stochastic epidemic model, using the WKB approximation and a Hamiltonian phase space, to the subcritical case. The limiting behavior of the model and approximation are qualitatively different in the subcritical case, requiring a novel analysis of the limiting behavior of the Hamiltonian system away from its deterministic subsystem. This yields a novel, general technique of approximation of the quasistationary distribution of stochastic epidemic and birth-death models, and may lead to techniques for analysis of these models beyond the quasistationary distribution. For a classic SIS model, the approximation found for the quasistationary distribution is very similar to published approximations but not identical. For a birth-death process without depletion of susceptibles, the approximation is exact. Dynamics on the phase plane similar to those predicted by the Hamiltonian analysis are demonstrated in cross-sectional data from trachoma treatment trials in Ethiopia, in which declining prevalences are consistent with subcritical epidemic dynamics

    Problematiza√ß√Ķes das pr√°ticas psi : articula√ß√Ķes com o pensamento foucaultiano

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    A problematiza√ß√£o das pr√°ticas de interven√ß√£o na √°rea psi tem sido orientada, muitas vezes, por alguns conceitos foucaultianos como poder, saber e regimes de verdade e tem introduzido quest√Ķes diferenciadas em rela√ß√£o √†quelas que tradicionalmente tem-se caracterizado como uma compreens√£o do que s√£o as pr√°ticas psicol√≥gicas. Se por um lado essas reflex√Ķes passam por uma desacomoda√ß√£o produzidas pelo olhar foucaultiano, por outro lado, esse inc√īmodo √© suscitado pelas pr√°ticas psicol√≥gicas tradicionais que desfrutam de um estatuto de legitimidade. Esses questionamentos instigam o pensar sobre deslocamentos nas formas de interven√ß√£o e compreens√£o das pr√°ticas psi.The problematization of the practices of intervention in Psychology has been helped by foucauldian concepts such as power, knowledge, and truth regimes. These concepts have altered the questions which have traditionally characterized views of psychological practices. However, such analysis has been accused of focusing only on the condition of visibility of power relations and modes of production of truth regimes, instead of instituting new forms of action or intervention. In this article we aim to produce a space for new links between foucauldian thought and current ways of conceiving the interventions in the psychology field

    Fractal Fidelity as a signature of Quantum Chaos

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    We analyze the fidelity of a quantum simulation and we show that it displays fractal fluctuations iff the simulated dynamics is chaotic. This analysis allows us to investigate a given simulated dynamics without any prior knowledge. In the case of integrable dynamics, the appearance of fidelity fractal fluctuations is a signal of a highly corrupted simulation. We conjecture that fidelity fractal fluctuations are a signature of the appearance of quantum chaos. Our analysis can be realized already by a few qubit quantum processor.Comment: 5 pages, 5 figure

    Leptogenesis in models with keV sterile neutrino dark matter

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    We analyze leptogenesis in gauge extensions of the Standard Model with keV sterile neutrino dark matter. We find that both the observed dark matter abundance and the correct baryon asymmetry of the Universe can simultaneously emerge in these models. Both the dark matter abundance and the leptogenesis are controlled by the out of equilibrium decays of the same heavy right handed neutrino.Comment: 6 pages, 1 figur
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