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15
Analog model for an expanding universe
, 2004
"... Over the last few years numerous papers concerning analog models for gravity have been published. It was shown that the dynamical equation of several systems (e.g. Bose–Einstein condensates with a sink or a vortex) have the same wave equation as light in a curvedspace (e.g. black holes). In the last ..."
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Over the last few years numerous papers concerning analog models for gravity have been published. It was shown that the dynamical equation of several systems (e.g. Bose–Einstein condensates with a sink or a vortex) have the same wave equation as light in a curvedspace (e.g. black holes). In the last few months several papers were released which deal with simulations of the universe. In this article the deSitter universe will be compared with a freely expanding threedimensional spherical Bose–Einstein condensate. Initially the condensate is in a harmonic trap, which suddenly will be switched off. At the same time a small perturbation will be injected in the center of the condensate cloud. The motion of the perturbation in the expanding condensate will be discussed, and after some transformations the similarity to an expanding universe will be shown.
A Unified Construction of Variational Methods for the Nonlinear Schrödinger Equation
, 1997
"... Based on an approach introduced by Gerjuoy, Rau, and Spruch, we construct variational principles in a systematic way for the nonlinear Schrödinger equation and obtain new variational principles for the case of GinzburgPitaevskiiGross equation (GPG) which is believed to describe accurately the Bose ..."
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Based on an approach introduced by Gerjuoy, Rau, and Spruch, we construct variational principles in a systematic way for the nonlinear Schrödinger equation and obtain new variational principles for the case of GinzburgPitaevskiiGross equation (GPG) which is believed to describe accurately the BoseEinstein condensation at zero temperature. As an application of these variational methods, a variational iteration method is proposed for calculating eigenvalue (chemical potential) and wave function for the GPG equation PACS number(s): 03.75.Fi, 05.30.Jp, 67.90.+z 1.
Declaration
, 2010
"... A thesis submitted in accordance with the requirements of ..."
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Editorial Board
, 2003
"... Number 25 Stability and instability of standing waves for nonlinear Schrödinger equations by ..."
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Number 25 Stability and instability of standing waves for nonlinear Schrödinger equations by
THE CONCEPT OF QUANTUM STATE: NEW VIEWS ON OLD PHENOMENA
"... “I think (…) that a theory cannot be produced from results of observations, but only from an invention.” “I am not ashamed to put the concept of «real state of a physical system » [“existing objectively, independently of any observation or measure, and that can in principle be described through t ..."
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“I think (…) that a theory cannot be produced from results of observations, but only from an invention.” “I am not ashamed to put the concept of «real state of a physical system » [“existing objectively, independently of any observation or measure, and that can in principle be described through the means of expression of physics”] at the very centre of my meditation.”
TimeDependent MeanField Equations For Systems of Bosons out of Equilibrium
, 2008
"... We analyze the Poisson structure of the timedependent meanfield equations for bosons and construct the LiePoisson bracket associated to these equations. The latter follow from the timedependent variational principle of Balian and Vénéroni when a gaussian Ansatz is chosen for the density operator ..."
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We analyze the Poisson structure of the timedependent meanfield equations for bosons and construct the LiePoisson bracket associated to these equations. The latter follow from the timedependent variational principle of Balian and Vénéroni when a gaussian Ansatz is chosen for the density operator. We perform a stability analysis of
Quons Restricted to the Antisymmetric Subspace: Formalism and Applications S.S. Avancini, F.F. de Souza Cruz, J.R. Marinelli,
, 2002
"... In this work we develop a formalism to treat quons restricted to the antisymmetric part of their manybody space. A model in which a system of identical quons interact through a pairing force is then solved within this restriction and the differences between our solution and the usual fermionic mode ..."
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In this work we develop a formalism to treat quons restricted to the antisymmetric part of their manybody space. A model in which a system of identical quons interact through a pairing force is then solved within this restriction and the differences between our solution and the usual fermionic model solution are then presented and discussed in detail. Possible connections to physical systems are also considered. PACS number(s):03.65.Fd;21.60.Fw 1