Bose polarons and rotating gases in an ultracold Bose-Fermi gas mixture of 40K and 87Rb atoms

<p>An ultracold Bose-Fermi gas mixture of <sup>40</sup>K and <sup>87</sup>Rb atoms has tunable interspecies interactions\&nbsp;<span style="line-height: 1.6em;">and therefore provides a fantastic platform for exploring not only few-body physics such\&nbsp;</span><span style="line-height: 1.6em;">as Feshbach molecule formation and Efimov trimers, but also many-body physics including Bose\&nbsp;</span><span style="line-height: 1.6em;">polarons, quantum Hall physics and so on. In this thesis, I present experimental evidence of Bose\&nbsp;</span><span style="line-height: 1.6em;">polarons in cold atoms obtained using radio-frequency spectroscopy to measure the excitation spectrum\&nbsp;</span><span style="line-height: 1.6em;">of fermionic <sup>40</sup>K impurities resonantly interacting with a BEC of <sup>87</sup>Rb atoms. These Bose\&nbsp;</span><span style="line-height: 1.6em;">polarons originate from the dressing of an impurity coupled to its environment, which is an important\&nbsp;</span><span style="line-height: 1.6em;">paradigm in quantum many-body physics. I also present initial work that launches an\&nbsp;</span><span style="line-height: 1.6em;">exciting new direction for our experiment, which is exploring rotating quantum gases. Goals for\&nbsp;</span><span style="line-height: 1.6em;">this work include studying both rotating Bose and Fermi super</span><span style="line-height: 1.6em;">fluids with tunable interactions as\&nbsp;</span><span style="line-height: 1.6em;">well as working toward rapidly rotating quantum gases in the quantum Hall regime. For these\&nbsp;</span><span style="line-height: 1.6em;">goals, a new all-optical trap for rotating gases was designed, implemented, and tested using a <sup>87</sup>Rb\&nbsp;</span><span style="line-height: 1.6em;">Bose-Einstein condensate.</span></p>
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University of Colorado Boulder
Boulder, CO
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