{"id":{"repo_id":"heid-diss","oai_identifier":"oai:archiv.ub.uni-heidelberg.de:5869"},"canonical_url":"https://search.dev.ndltd.org/etd/heid-diss/oai:archiv.ub.uni-heidelberg.de:5869","repository":{"repo_id":"heid-diss","name":"Universität Heidelberg","base_url":"http://archiv.ub.uni-heidelberg.de/volltextserver/cgi/oai2"},"display":{"title":"Observation of nonlinear tunneling of a Bose-Einstein condensate in a single Josephson junction","abstract":"In this thesis, I present the first experimental implementation of a Josephson junction for Bose-Einstein condensates. The weak link between two BECs constitutes the nonlinear generalization of the well known Josephson junction of weakly-coupled superconductors that are separated by a thin insulating barrier. In our experiment, the required overlap of two macroscopic wavefunctions is provided by loading a BEC into an optical double well potential. It is realized by a superposition of a one-dimensional optical lattice with a focused laser beam optical dipole trap. The tunneling dynamics between the two potential wells exhibits two distinct dynamical regimes. For small initial population imbalances of the two wells we observe nearly sinusoidal Josephson tunneling oscillations, which are characterized by an oscillating population and relative phase. The situation changes drastically, if the initial population imbalance is chosen above a critical value. In this case, resonant tunneling between the two wells is prohibited because the difference between the on-site particle interaction energies in the two wells exceeds the tunneling energy splitting. As a consequence, the atomic distribution becomes self-locked and the relative phase evolves unbound in time. This regime of prohibited tunneling, which has no analogon in superconducting Josephson junctions, is called “macroscopic quantum self-trapping”.","abstract_html":"In this thesis, I present the first experimental implementation of a Josephson junction for Bose-Einstein condensates. The weak link between two BECs constitutes the nonlinear generalization of the well known Josephson junction of weakly-coupled superconductors that are separated by a thin insulating barrier. In our experiment, the required overlap of two macroscopic wavefunctions is provided by loading a BEC into an optical double well potential. It is realized by a superposition of a one-dimensional optical lattice with a focused laser beam optical dipole trap. The tunneling dynamics between the two potential wells exhibits two distinct dynamical regimes. For small initial population imbalances of the two wells we observe nearly sinusoidal Josephson tunneling oscillations, which are characterized by an oscillating population and relative phase. The situation changes drastically, if the initial population imbalance is chosen above a critical value. In this case, resonant tunneling between the two wells is prohibited because the difference between the on-site particle interaction energies in the two wells exceeds the tunneling energy splitting. As a consequence, the atomic distribution becomes self-locked and the relative phase evolves unbound in time. This regime of prohibited tunneling, which has no analogon in superconducting Josephson junctions, is called “macroscopic quantum self-trapping”.","abstract_has_math":false,"creators":["Albiez, Michael"],"institution":"Universität Heidelberg","degree_name":null,"degree_level":"thesis.doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":["Dr. Oberthaler, Markus"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2005,"date_issued":"2005-10-19","date_published":"2005-10-19","updated_at":"2026-07-24T02:30:12Z","subjects":[],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://www.ub.uni-heidelberg.de/archiv/5869","outbound_label":"Repository record","outbound_source":"source_url"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Oberthaler, Markus"]},{"key":"dc:creator","label":"Author","values":["Albiez, Michael"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:publisher","label":"Institution","values":["Universitätsbibliothek Heidelberg"]},{"key":"dc:type","label":"Dc Type","values":["doctoralThesis"]},{"key":"thesis:degree_level","label":"Degree Level","values":["thesis.doctoral"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Universität Heidelberg"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In this thesis, I present the first experimental implementation of a Josephson junction for Bose-Einstein condensates. The weak link between two BECs constitutes the nonlinear generalization of the well known Josephson junction of weakly-coupled superconductors that are separated by a thin insulating barrier. In our experiment, the required overlap of two macroscopic wavefunctions is provided by loading a BEC into an optical double well potential. It is realized by a superposition of a one-dimensional optical lattice with a focused laser beam optical dipole trap. The tunneling dynamics between the two potential wells exhibits two distinct dynamical regimes. For small initial population imbalances of the two wells we observe nearly sinusoidal Josephson tunneling oscillations, which are characterized by an oscillating population and relative phase. The situation changes drastically, if the initial population imbalance is chosen above a critical value. In this case, resonant tunneling between the two wells is prohibited because the difference between the on-site particle interaction energies in the two wells exceeds the tunneling energy splitting. As a consequence, the atomic distribution becomes self-locked and the relative phase evolves unbound in time. This regime of prohibited tunneling, which has no analogon in superconducting Josephson junctions, is called “macroscopic quantum self-trapping”.","In der vorliegenden Arbeit wird die erste experimentelle Realisierung eines Josephsonkontaktes für Bose-Einstein Kondensate beschrieben. Das physikalische System zweier schwach gekoppelter BECs steht in enger Analogie zu den bekannten Josephsonkontakten in Supraleitern und Suprafluiden. Die schwache Kopplung wird in unserem Experiment mit Hilfe eines optischen Doppelmuldenpotentials realisiert, in das das BEC hinein geladen wird. Es entsteht durch die Superposition eines eindimensionalen optischen Gitters und zweier gekreuzter fokussierten Laserstrahls, die einen dreidimensionalen harmonischen Einschluß erzeugt. Die Tunneldynamik in diesem bosonischen Josephson Kontakt zeigt zwei deutlich unterscheidbare dynamische Regimes. Für kleine anfängliche Besetzungzahlunterschiede der beiden Potentialminima werden nahezu sinusförmige Josephson-Oszillationen beobachtet, die sowohl durch eine oszillierende Besetzung als auch durch eine oszillierende relative Phase der beiden BECs charakterisiert ist. Wird der anfängliche Besetzungsunterschied größer gewählt als ein kritischer Wert, beobachtet man, daß sich die Besetzung im Laufe der Zeit kaum mehr ändert, wohingegen die relative Phase der beiden Wellenpakete linear anw¨achst. Dieses dynamische Verhalten, das als \"macroscopic self-trapping\" bezeichnet wird, wird dadurch verursacht, daß resonantes Tunneln aufgrund stark unterschiedlicher Wechselwirkungsenergien in den beiden Potentialtöpfen unterdrückt ist und hat keine direkte Analogie in supraleitenden Josephsonkontakten."]},{"key":"dc:format.medium","label":"Dc Format Medium","values":["application/pdf"]},{"key":"dc:title","label":"Title","values":["Observation of nonlinear tunneling of a Bose-Einstein condensate in a single Josephson junction","Beobachtung von nichtlinearer Tunneldynamik eines Bose-Einstein Kondensats in einem Josephsonkontakt"]}]}],"canonical_facts":{"dc:contributor":["Dr. Oberthaler, Markus"],"dc:creator":["Albiez, Michael"],"dc:description.abstract":["In this thesis, I present the first experimental implementation of a Josephson junction for Bose-Einstein condensates. The weak link between two BECs constitutes the nonlinear generalization of the well known Josephson junction of weakly-coupled superconductors that are separated by a thin insulating barrier. In our experiment, the required overlap of two macroscopic wavefunctions is provided by loading a BEC into an optical double well potential. It is realized by a superposition of a one-dimensional optical lattice with a focused laser beam optical dipole trap. The tunneling dynamics between the two potential wells exhibits two distinct dynamical regimes. For small initial population imbalances of the two wells we observe nearly sinusoidal Josephson tunneling oscillations, which are characterized by an oscillating population and relative phase. The situation changes drastically, if the initial population imbalance is chosen above a critical value. In this case, resonant tunneling between the two wells is prohibited because the difference between the on-site particle interaction energies in the two wells exceeds the tunneling energy splitting. As a consequence, the atomic distribution becomes self-locked and the relative phase evolves unbound in time. This regime of prohibited tunneling, which has no analogon in superconducting Josephson junctions, is called “macroscopic quantum self-trapping”.","In der vorliegenden Arbeit wird die erste experimentelle Realisierung eines Josephsonkontaktes für Bose-Einstein Kondensate beschrieben. Das physikalische System zweier schwach gekoppelter BECs steht in enger Analogie zu den bekannten Josephsonkontakten in Supraleitern und Suprafluiden. Die schwache Kopplung wird in unserem Experiment mit Hilfe eines optischen Doppelmuldenpotentials realisiert, in das das BEC hinein geladen wird. Es entsteht durch die Superposition eines eindimensionalen optischen Gitters und zweier gekreuzter fokussierten Laserstrahls, die einen dreidimensionalen harmonischen Einschluß erzeugt. Die Tunneldynamik in diesem bosonischen Josephson Kontakt zeigt zwei deutlich unterscheidbare dynamische Regimes. Für kleine anfängliche Besetzungzahlunterschiede der beiden Potentialminima werden nahezu sinusförmige Josephson-Oszillationen beobachtet, die sowohl durch eine oszillierende Besetzung als auch durch eine oszillierende relative Phase der beiden BECs charakterisiert ist. Wird der anfängliche Besetzungsunterschied größer gewählt als ein kritischer Wert, beobachtet man, daß sich die Besetzung im Laufe der Zeit kaum mehr ändert, wohingegen die relative Phase der beiden Wellenpakete linear anw¨achst. Dieses dynamische Verhalten, das als \"macroscopic self-trapping\" bezeichnet wird, wird dadurch verursacht, daß resonantes Tunneln aufgrund stark unterschiedlicher Wechselwirkungsenergien in den beiden Potentialtöpfen unterdrückt ist und hat keine direkte Analogie in supraleitenden Josephsonkontakten."],"dc:format.medium":["application/pdf"],"dc:publisher":["Universitätsbibliothek Heidelberg"],"dc:title":["Observation of nonlinear tunneling of a Bose-Einstein condensate in a single Josephson junction","Beobachtung von nichtlinearer Tunneldynamik eines Bose-Einstein Kondensats in einem Josephsonkontakt"],"dc:type":["doctoralThesis"],"thesis:degree_level":["thesis.doctoral"],"thesis:institution_name":["Universität Heidelberg"]},"updated_at":"2026-07-24T02:30:12Z"}