Dokument: Isotope dependent interactions in a mixture of ultracold atoms

Titel:	Isotope dependent interactions in a mixture of ultracold atoms
URL für Lesezeichen:	https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=15455
URN (NBN):	urn:nbn:de:hbz:061-20100629-140500-2
Kollektion:	Dissertationen
Sprache:	Englisch
Dokumententyp:	Wissenschaftliche Abschlussarbeiten » Dissertation
Medientyp:	Text
Autor:	Baumer, Florian [Autor]
Dateien:	[Dateien anzeigen] Adobe PDF [Details] 5,58 MB in einer Datei [ZIP-Datei erzeugen] Dateien vom 29.06.2010 / geändert 29.06.2010
Beitragende:	Prof. Dr. Görlitz, Axel [Gutachter] Prof. Dr. Pretzler, Georg [Gutachter]
Stichwörter:	Experimentelle Physik, Quantenoptik, ultrakalte Gemische, Rubidium, Ytterbium, Streulänge, BEC
Dewey Dezimal-Klassifikation:	500 Naturwissenschaften und Mathematik » 530 Physik
Beschreibung:	Within the scope of this thesis, comprehensive experimental studies on interspecies interactions between 87Rb and various isotopes of Yb at temperatures in the µK regime have been performed. The interactions between Yb and 87Rb manifested themselves through interspecies thermalization and - in the case of 174Yb and 87Rb - through phase separation. The experimental investigations described in this thesis were carried out within a research project, whose long term goal is the creation of ultracold YbRb molecules. The experimental apparatus is designed for combined cooling and trapping of gaseous Yb and Rb atomic samples to the µK and nK regime. Due to the particular magnetic properties of Rb and Yb, a unique combination of trapping potentials, which allows for independent manipulation of ultracold 87Rb and Yb atoms, was used for the described measurements. The combined trap setup consisted of a Ioffe-Pritchard-type magnetic trap (MT) for 87Rb and a bichromatic optical dipole trap (BIODT) for Yb. The main scientific result of this PhD work is the observation of phase separation in a thermal mixture of 174Yb and 87Rb in the µK regime and the detailed experimental study and theoretical analysis of this unexpected effect. Analysis of the experimental observations required accurate modeling of the trapping potentials in order to extract quantitative results on the interspecies interaction. These results can be related to the 174Yb 87Rb interspecies s-wave scattering length, using an approach, which not only describes mean field effects but also includes multiple-particle interactions. This analysis yields a value for the s-wave scattering length of a_(87-174)=4710 (+3970) (-1520) a0, which is extraordinarily large. Indeed, this is to our knowledge the largest interspecies scattering length that has been observed to date at zero magnetic field. In contrast to observations of phase separation in other systems that have been made so far, phase separation between 174Yb and 87Rb as described in this PhD work is observed in purely thermal and not quantum degenerate samples. In this thesis, the study of phase separation in a 174Yb87Rb mixture was supplemented by an investigation of elastic collision rates for several of the Yb isotopes. The most notable finding was that for the combination \Yb{170}87Rb the interspecies scattering length has a value of a_(87-174)=6.6 (+3.5) (-2.9)a0 and is thus extremely small. The results of our studies on interspecies interactions between 87Rb and Yb can be used for model calculations on the YbRb molecular ground state potential: E. Tiesinga and S. Maxwell from the atomic theory group at NIST determined a Lennard-Jones potential, which quantitatively reproduces the present experimental observations. This knowledge will significantly help to provide a strategy for the controlled transfer of excited state YbRb* molecules to a selected ground state.
Lizenz:	Urheberrechtsschutz
Fachbereich / Einrichtung:	Mathematisch- Naturwissenschaftliche Fakultät » WE Physik » Experimentalphysik
Dokument erstellt am:	29.06.2010
Dateien geändert am:	29.06.2010
Promotionsantrag am:	25.03.2010
Datum der Promotion:	29.04.2010