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Search Results: 1 - 10 of 191443 matches for " Horia D. Cornean "
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On the Magnetization of a Charged Bose Gas in the Canonical Ensemble
Horia D. Cornean
Mathematics , 2006,
Abstract: Consider a charged Bose gas without self-interactions, confined in a three dimensional cubic box of side $L\geq 1$ and subjected to a constant magnetic field $B\neq 0$. If the bulk density of particles $\rho$ and the temperature $T$ are fixed, then define the canonical magnetization as the partial derivative with respect to $B$ of the reduced free energy. Our main result is that it admits thermodynamic limit for all strictly positive $\rho$, $T$ and $B$. It is also proven that the canonical and grand canonical magnetizations (the last one at fixed average density) are equal up to the surface order corrections.
On the Lipschitz continuity of spectral bands of Harper-like and magnetic Schroedinger operators
Horia D. Cornean
Mathematics , 2009, DOI: 10.1007/s00023-010-0048-1
Abstract: We show for a large class of discrete Harper-like and continuous magnetic Schrodinger operators that their band edges are Lipschitz continuous with respect to the intensity of the external constant magnetic field. We generalize a result obtained by J. Bellissard in 1994, and give examples in favor of a recent conjecture of G. Nenciu.
Faraday effect revisited: sum rules and convergence issues
Horia D. Cornean,Gheorghe Nenciu
Physics , 2010, DOI: 10.1088/1751-8113/43/47/474012
Abstract: This is the third paper of a series revisiting the Faraday effect. The question of the absolute convergence of the sums over the band indices entering the Verdet constant is considered. In general, sum rules and traces per unit volume play an important role in solid state physics, and they give rise to certain convergence problems widely ignored by physicists. We give a complete answer in the case of smooth potentials and formulate an open problem related to less regular perturbations.
On the cotunneling regime of interacting quantum dots
Horia D. Cornean,Valeriu Moldoveanu
Physics , 2011, DOI: 10.1088/1751-8113/44/30/305002
Abstract: Consider a bunch of interacting electrons confined in a quantum dot. The later is suddenly coupled to semi-infinite biased leads at an initial instant $t=0$. We identify the dominant contribution to the ergodic current in the off-resonant transport regime, in which the discrete spectrum of the quantum dot is well separated from the absolutely continuous spectrum of the leads. Our approach allows for arbitrary strength of the electron-electron interaction while the current is expanded in even powers of the (weak) lead-dot hopping constant $\tau$. We provide explicit calculations for sequential tunneling and cotunneling contributions to the current. In the interacting case it turns out that the cotunneling current depends on the initial many-body configuration of the sample, while in the non-interacting case it does not, and coincides with the first term in the expansion of the Landauer formula w.r.t $\tau$.
On the regularity of the Hausdorff distance between spectra of perturbed magnetic Hamiltonians
Horia D. Cornean,Radu Purice
Mathematics , 2012, DOI: 10.1007/978-3-0348-0414-1_4
Abstract: We study the regularity properties of the Hausdorff distance between spectra of continuous Harper-like operators. As a special case we obtain H\"{o}lder continuity of this Hausdorff distance with respect to the intensity of the magnetic field for a large class of magnetic elliptic (pseudo)differential operators with long range magnetic fields.
Spectral edge regularity of magnetic Hamiltonians
Horia D. Cornean,Radu Purice
Mathematics , 2014, DOI: 10.1112/jlms/jdv019
Abstract: We analyse the spectral edge regularity of a large class of magnetic Hamiltonians when the perturbation is generated by a globally bounded magnetic field. We can prove Lipschitz regularity of spectral edges if the magnetic field perturbation is either constant or slowly variable. We also recover an older result by G. Nenciu who proved Lipschitz regularity up to a logarithmic factor for general globally bounded magnetic field perturbations.
Diamagnetic expansions for perfect quantum gases II: uniform bounds
Philippe Briet,Horia D. Cornean,Delphine Louis
Physics , 2007,
Abstract: Consider a charged, perfect quantum gas, in the effective mass approximation, and in the grand-canonical ensemble. We prove in this paper that the generalized magnetic susceptibilities admit the thermodynamic limit for all admissible fugacities, uniformly on compacts included in the analyticity domain of the grand-canonical pressure. The problem and the proof strategy were outlined in \cite{3}. In \cite{4} we proved in detail the pointwise thermodynamic limit near $z=0$. The present paper is the last one of this series, and contains the proof of the uniform bounds on compacts needed in order to apply Vitali's Convergence Theorem.
Diamagnetism of quantum gases with singular potentials
Philippe Briet,Horia D. Cornean,Baptiste Savoie
Physics , 2010, DOI: 10.1088/1751-8113/43/47/474008
Abstract: We consider a gas of quasi-free quantum particles confined to a finite box, subjected to singular magnetic and electric fields. We prove in great generality that the finite volume grand-canonical pressure is jointly analytic in the chemical potential ant the intensity of the external magnetic field. We also discuss the thermodynamic limit.
A partition-free approach to transient and steady-state charge currents
Horia D. Cornean,Celine Gianesello,Valentin Zagrebnov
Physics , 2010, DOI: 10.1088/1751-8113/43/47/474011
Abstract: We construct a non-equilibrium steady state and calculate the corresponding current for a mesoscopic Fermi system in the partition-free setting. To this end we study a small sample coupled to a finite number of semi-infinite leads. Initially, the whole system of quasi-free fermions is in a grand canonical equilibrium state. At t = 0 we turn on a potential bias on the leads and let the system evolve. We study how the charge current behaves in time and how it stabilizes itself around a steady state value, which is given by a Landauer-type formula.
On the skeleton method and an application to a quantum scissor
Horia D. Cornean,Pierre Duclos,Benjamin Ricaud
Physics , 2008,
Abstract: In the spectral analysis of few one dimensional quantum particles interacting through delta potentials it is well known that one can recast the problem into the spectral analysis of an integral operator (the skeleton) living on the submanifold which supports the delta interactions. We shall present several tools which allow direct insight into the spectral structure of this skeleton. We shall illustrate the method on a model of a two dimensional quantum particle interacting with two infinitely long straight wires which cross one another at a certain angle : the quantum scissor.
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