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Coherent Transport of Matter Waves in Disordered Optical Potentials

URN to cite this document: urn:nbn:de:bvb:703-opus-2879

Title data

Kuhn, Robert:
Coherent Transport of Matter Waves in Disordered Optical Potentials.
Bayreuth , 2007
( Doctoral thesis, 2007 , University of Bayreuth, Faculty of Mathematics, Physics and Computer Sciences)

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Abstract

The development of modern techniques for the cooling and the manipulation of atoms in recent years, and the possibility to create Bose-Einstein condensates and degenerate Fermi gases and to load them into regular optical lattices or disordered optical potentials, has evoked new interest for the disorder-induced localization of ultra-cold atoms. This work studies the transport properties of matter waves in disordered optical potentials, which are also known as speckle potentials. The effect of correlated disorder on localization is first studied numerically in the framework of the Anderson model. The relevant transport parameters in the configuration average over many different realizations of the speckle potential are then determined analytically, using self-consistent diagrammatic perturbation techniques. This allows to make predictions for a possible experimental observation of coherent transport phenomena for cold atoms in speckle potentials. Of particular importance are the spatial correlations of the speckle fluctuations, which are responsible for the anisotropic character of the single scattering processes in the effective medium. Coherent multiple scattering leads to quantum interference effects, which entail a renormalization of the diffusion constant as compared to the classical description. This so-called weak localization of matter waves is studied as the underlying mechanism for the disorder-driven transition to the Anderson-localization regime, explicitly taking into account the correlations of the speckle fluctuations.

Abstract in another language

Le développement de techniques modernes pour le refroidissement et le piégeage d´atomes et la possibilité de charger des réseaux optiques ou des potentiels désordonnés avec des condensats de Bose ou des gaz de Fermi dégénérés a déclenché un intérêt nouveau pour la localisation des atomes ultra-froids. Dans le présent travail théorique nous étudions le transport cohérent des ondes de matière dans des potentiels lumineux désordonnés, ou échantillons de tavelures (speckle). L´influence du désordre corrélé est d´abord étudié numériquement dans le cadre du modèle d´Anderson. Un calcul auto-consistante diagrammatique permet finalement de déterminer analytiquement les paramètres fondamentaux de transport dans le régime de faible désordre. Une importance cruciale pour le calcul analytique revient à la fonction de corrélation spatiale des fluctuations du potentiel désordonné qui détermine le degré d´anisotropie d´un événement de collision. Nous considérons en particulier la transition du régime de la localisation faible à celui de la localisation forte. Dans ce cas la constante de diffusion des ondes de matière diminue et tend vers zéro au seuil de la localisation forte, ce qui décrit la transition d´Anderson. Dans le présent travail on calcule la renormalisation de la constante de diffusion due à l´interférence cohérente des ondes de matière en tenant compte explicitement de la correlation des fluctuations du potentiel désordonné.

Further data

Item Type: Doctoral thesis (No information)
Keywords: Speckle; Anderson-Lokalisation; Lokalisation; Vielfachstreuung; Schwache Lokalisation; Starke Lokalisation; Speckle; Anderson-Localization; Localization; Disorder; Quantum Transport; Diagrammatic Perturbation Theory; Multiple Scattering
DDC Subjects: 500 Science > 530 Physics
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics
Faculties
Faculties > Faculty of Mathematics, Physics und Computer Science
Language: English
Originates at UBT: Yes
URN: urn:nbn:de:bvb:703-opus-2879
Date Deposited: 25 Apr 2014 12:19
Last Modified: 10 Nov 2014 10:48
URI: https://epub.uni-bayreuth.de/id/eprint/732

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