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  • 2000-2004  (6)
  • 1975-1979
  • 1960-1964
  • 1890-1899
  • 2001  (6)
  • PACS. 03.75.Be Atom and neutron optics – 42.25.Fx Diffraction and scattering  (2)
  • PACS. 32.80.Pj Optical cooling of atoms; trapping – 42.50.Vk Mechanical effects of light on atoms, molecules, electrons, and ions  (2)
  • PACS. 64.70.Pf Glass transitions – 05.70.Ln Nonequilibrium and irreversible thermodynamics  (2)
Datenquelle
Materialart
Erscheinungszeitraum
  • 2000-2004  (6)
  • 1975-1979
  • 1960-1964
  • 1890-1899
Jahr
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Validity of the zero-thermodynamic law in off-equilibrium coupled harmonic oscillators (2001)
    Springer
    The European physical journal 20 (2001), S. 105-122 
    Details
    ISSN: 1434-6036
    Schlagwort(e): PACS. 64.70.Pf Glass transitions – 05.70.Ln Nonequilibrium and irreversible thermodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: In order to describe the thermodynamics of the glassy systems it has been recently introduced an extra parameter, the effective temperature which generalizes the fluctuation-dissipation theorem (FDT) to off-equilibrium systems and supposedly describes thermal fluctuations around the aging state. Using this concept we investigate the applicability of a zeroth thermodynamic law for non-equilibrium systems. In particular we study two coupled systems of harmonic oscillators with Monte Carlo dynamics. We analyze in detail two types of dynamics: 1) sequential dynamics where the coupling between the subsystems comes only from the Hamiltonian and 2) parallel dynamics where there is a further coupling between the subsystems arising from the dynamics. We show that the coupling described in the first case is not enough to make asymptotically the effective temperatures of the two interacting subsystems equalize, the reason being the too small thermal conductivity between them in the aging state. This explains why different interacting degrees of freedom in structural glasses may stay at different effective temperatures without never mutually thermalizing.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01313919
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  • 2
    Digitale Medien
    Digitale Medien
    Heat transfer and Fourier's law in off-equilibrium systems (2001)
    Springer
    The European physical journal 21 (2001), S. 115-120 
    Details
    ISSN: 1434-6036
    Schlagwort(e): PACS. 64.70.Pf Glass transitions – 05.70.Ln Nonequilibrium and irreversible thermodynamics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: We study the most suitable procedure to measure the effective temperature in off-equilibrium systems. We analyze the stationary current established between an off-equilibrium system and a thermometer and the necessary conditions for that current to vanish. We find that the thermometer must have a short characteristic time-scale compared to the typical decorrelation time of the glassy system to correctly measure the effective temperature. This general conclusion is confirmed analyzing an ensemble of harmonic oscillators with Monte Carlo dynamics as an illustrative example of a solvable model of a glass. We also find that the current defined allows to extend Fourier's law to the off-equilibrium regime by consistently defining effective transport coefficients. Our results for the oscillator model explain why thermal conductivities between thermalized and frozen degrees of freedom in structural glasses are extremely small.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01315082
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Atom diffraction from magnetic gratings in the thin phase-grating approximation (2001)
    Springer
    The European physical journal 14 (2001), S. 289-297 
    Details
    ISSN: 1434-6079
    Schlagwort(e): PACS. 03.75.Be Atom and neutron optics – 42.25.Fx Diffraction and scattering
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: The problem of atom diffraction from a reflecting magnetic diffraction grating is solved in the thin phase-grating approximation. The general problem for scalar diffraction is modelled using a semi-classical method in which the grating potential is separated into a reflecting term and a diffracting term. The trajectory of the atom in the reflecting potential is solved classically and the atom wave function in the diffracting potential found by integrating the phase change along the classical trajectory. The diffraction orders are obtained after Fourier transforming the result. This can be done independently of the grating potential resulting in a general formula for the diffraction efficiencies. The general result is applied to the problem of atom diffraction from a magnetic grating. Several approximations are required to reduce the problem to a form amenable to analytic solution. The results are compared with an accurate numerical method.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100530170195
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  • 4
    Digitale Medien
    Digitale Medien
    Modelling the diffraction of laser-cooled atoms from magnetic gratings (2001)
    Springer
    The European physical journal 14 (2001), S. 111-118 
    Details
    ISSN: 1434-6079
    Schlagwort(e): PACS. 03.75.Be Atom and neutron optics – 42.25.Fx Diffraction and scattering
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: The diffraction of laser-cooled atoms from a spatially-periodic potential is modelled using rigorous coupled-wave analysis. This numerical technique, normally applied to light-diffraction, is adapted for use with atomic de Broglie waves incident on a reflecting diffraction grating. The technique approximates the potential by a large number of constant layers and successively solves the complex eigenvalue problem in each layer, propagating the solution up to the surface of the grating. The method enables the diffraction efficiencies to be calculated for any periodic potential. The results from the numerical model are compared with the thin phase-grating approximation formulae for evanescent light-wave diffraction gratings and idealised magnetic diffraction gratings. The model is applied to the problem of diffracting Rb atoms from a grating made from an array of permanent magnets.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100530170242
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  • 5
    Digitale Medien
    Digitale Medien
    Single-beam optical bottle for cold atoms using a conical lens (2001)
    Springer
    The European physical journal 14 (2001), S. 373-376 
    Details
    ISSN: 1434-6079
    Schlagwort(e): PACS. 32.80.Pj Optical cooling of atoms; trapping – 42.50.Vk Mechanical effects of light on atoms, molecules, electrons, and ions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: We report a new method to generate an optical dipole potential with a null intensity region surrounded in all directions by light walls. This is achieved with a simple scheme based on a conical lens. Applications to optical trapping of neutral atoms are discussed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100530170205
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    A continuous cold atomic beam from a magneto-optical trap (2001)
    Springer
    The European physical journal 15 (2001), S. 245-249 
    Details
    ISSN: 1434-6079
    Schlagwort(e): PACS. 32.80.Pj Optical cooling of atoms; trapping – 42.50.Vk Mechanical effects of light on atoms, molecules, electrons, and ions
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Physik
    Notizen: Abstract: We have developed and characterized a new method to produce a continuous beam of cold atoms from a standard vapour-cell magneto-optical trap (MOT). The experimental apparatus is very simple. Using a single laser beam it is possible to hollow out in the source MOT a direction of unbalanced radiation pressure along which cold atoms can be accelerated out of the trap. The transverse cooling process that takes place during the extraction reduces the beam divergence. The atomic beam is used to load a magneto-optical trap operating in an ultra-high vacuum environment. At a vapour pressure of 10-8mbar in the loading cell, we have produced a continuous flux of 7×107atoms/s at the recapture cell with a mean velocity of 14 m/s. A comparison of this method with a pulsed transfer scheme is presented.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s100530170172
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