Single photon photoassociation in a lithium-7 BEC near a Feshbach resonance

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dc.contributor.advisorHulet, Randall G.
dc.creatorJunker, Mark
dc.date.accessioned2018-12-03T18:31:50Z
dc.date.available2018-12-03T18:31:50Z
dc.date.issued2008
dc.description.abstractThe rate of photoassociation (PA) determines how quickly molecules form from atoms illuminated by a resonant laser pulse. Knowledge of limits of this molecular formation rate provide a fundamental component on the maximum rate that a tightly bound ground state molecular Bose-Einstein condensate (BEC) could be formed using a two-photon transition. This molecular synthesis represents the beginning of a new era of ultracold quantum chemistry. The available Feshbach resonance in this system is an indispensable tool to increase the molecular formation rate due to PA in the anticipation of revealing these fundamental rate limits. While the rate saturates in a thermal gas, no evidence of saturation has yet been observed in a BEC. A loss of atoms due to a PA pulse tuned to the v " = 83 excited state molecular vibrational level provides the measurement of the PA rate. The rate varies by several orders of magnitude either by tuning the magnetic field near a Feshbach resonance or by adjusting the PA intensity. We measure the PA rate at magnetic fields between 550-900 Gauss in a BEC and a thermal gas, which is near the Feshbach resonance at 736 Gauss. The rapidly changing rate near the Feshbach resonance reflects the overlap between the ground state and the excited state wavefunctions. We present the first quantitative measurement of the PA rate near a Feshbach resonance. We measure the magnetic field dependence of the molecular resonance position near the Feshbach resonance. We introduce the first observation of a positive energy shift associated with photoassociation. The measured energy shift asymptotically diverges as it approaches the Feshbach resonance and agrees qualitatively with described theory at all magnetic fields. We observe intensity dependent saturation in the PA rate in a thermal gas and the measurements qualitatively agree with a unitarity limited rate. The first conclusive evidence for a suppression of the PA rate occurs for intensities above the saturation intensity. We report the first observed saturation of the PA rate in a BEC. Three separate theories present possible mechanisms for the observed saturation.
dc.format.extent198 pp
dc.identifier.callnoTHESIS PHYS. 2008 JUNKER
dc.identifier.citationJunker, Mark. "Single photon photoassociation in a lithium-7 BEC near a Feshbach resonance." (2008) Diss., Rice University. <a href="https://hdl.handle.net/1911/103607">https://hdl.handle.net/1911/103607</a>.
dc.identifier.digital304510434
dc.identifier.urihttps://hdl.handle.net/1911/103607
dc.language.isoeng
dc.rightsCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.
dc.subjectMolecular physics
dc.subjectCondensed matter physics
dc.subjectPure sciences
dc.subjectBose-Einstein condensate
dc.subjectFeshbach resonance
dc.subject.Lithium-7
dc.subjectPhotoassociation
dc.titleSingle photon photoassociation in a lithium-7 BEC near a Feshbach resonance
dc.typeThesis
dc.type.materialText
thesis.degree.departmentPhysics
thesis.degree.disciplineNatural Sciences
thesis.degree.grantorRice University
thesis.degree.levelDoctoral
thesis.degree.nameDoctor of Philosophy
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