7,750 research outputs found

    Scaling behaviour of trapped bosonic particles in two dimensions at finite temperature

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    In the framework of the trap-size scaling theory, we study the scaling properties of the Bose-Hubbard model in two dimensions in the presence of a trapping potential at finite temperature. In particular, we provide results for the particle density and the density-density correlator at the Mott transitions and within the superfluid phase. For the former quantity, numerical outcomes are also extensively compared to Local Density Approximation predictions.Comment: 8 pages, 9 figure

    Magnetic charge superselection in the deconfined phase of Yang-Mills theory

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    The vacuum expectation value of an operator carrying magnetic charge is studied numerically for temperatures above the deconfinement temperature in SU(2) and SU(3) gauge theory. By analyzing its finite size behaviour, this is found to be exactly zero in the thermodynamical limit for any T > T_c whenever the magnetic charge of the operator is different from zero. These results show that magnetic charge is superselected in the hot phase of quenched QCD.Comment: 4 pages, 6 figures, revtex

    Response to "Comment on Static correlations functions and domain walls in glass-forming liquids: The case of a sandwich geometry" [J. Chem. Phys. 144, 227101 (2016)]

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    The point-to-set correlation function has proved to be a very valuable tool to probe structural correlations in disordered systems, but more than that, its detailed behavior has been used to try to draw information on the mechanisms leading to glassy behavior in supercooled liquids. For this reason it is of primary importance to discern which of those details are peculiar to glassy systems, and which are general features of confinement. Within the present response we provide an answer to the concerns raised in [J. Chem. Phys. 144, 227101 (2016)]

    A Framework to Control Functional Connectivity in the Human Brain

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    In this paper, we propose a framework to control brain-wide functional connectivity by selectively acting on the brain's structure and parameters. Functional connectivity, which measures the degree of correlation between neural activities in different brain regions, can be used to distinguish between healthy and certain diseased brain dynamics and, possibly, as a control parameter to restore healthy functions. In this work, we use a collection of interconnected Kuramoto oscillators to model oscillatory neural activity, and show that functional connectivity is essentially regulated by the degree of synchronization between different clusters of oscillators. Then, we propose a minimally invasive method to correct the oscillators' interconnections and frequencies to enforce arbitrary and stable synchronization patterns among the oscillators and, consequently, a desired pattern of functional connectivity. Additionally, we show that our synchronization-based framework is robust to parameter mismatches and numerical inaccuracies, and validate it using a realistic neurovascular model to simulate neural activity and functional connectivity in the human brain.Comment: To appear in the proceedings of the 58th IEEE Conference on Decision and Contro

    Gauge-invariant quark-antiquark nonlocal condensates in lattice QCD

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    We study, by numerical simulations on a lattice, the behaviour of the gauge-invariant quark-antiquark nonlocal condensates in the QCD vacuum with dynamical fermions. A determination is also done in the quenched approximation and the results are compared with the full-QCD case. The fermionic correlation length is extracted and compared with the analogous gluonic quantity.Comment: 14 pages, LaTeX file, + 6 PS figure

    Efficient universal programmable quantum measurements

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    A universal programmable detector is a device that can be tuned to perform any desired measurement on a given quantum system, by changing the state of an ancilla. With a finite dimension d for the ancilla only approximate universal programmability is possible, with "size" d=f(1/e) increasing function of the "accuracy" 1/e. In this letter we show that, much better than the exponential size known in the literature, one can achieve polynomial size. An explicit example with linear size is also presented. Finally, we show that for covariant measurements exact programmability is feasible.Comment: 4 pages, RevTex
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