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

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dc.contributor.advisorHulet, Randall G.en_US
dc.creatorJunker, Marken_US
dc.date.accessioned2018-12-03T18:31:50Zen_US
dc.date.available2018-12-03T18:31:50Zen_US
dc.date.issued2008en_US
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.en_US
dc.format.extent198 ppen_US
dc.identifier.callnoTHESIS PHYS. 2008 JUNKERen_US
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>.en_US
dc.identifier.digital304510434en_US
dc.identifier.urihttps://hdl.handle.net/1911/103607en_US
dc.language.isoengen_US
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.en_US
dc.subjectMolecular physicsen_US
dc.subjectCondensed matter physicsen_US
dc.subjectPure sciencesen_US
dc.subjectBose-Einstein condensateen_US
dc.subjectFeshbach resonanceen_US
dc.subject.Lithium-7en_US
dc.subjectPhotoassociationen_US
dc.titleSingle photon photoassociation in a lithium-7 BEC near a Feshbach resonanceen_US
dc.typeThesisen_US
dc.type.materialTexten_US
thesis.degree.departmentPhysicsen_US
thesis.degree.disciplineNatural Sciencesen_US
thesis.degree.grantorRice Universityen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophyen_US
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