000000855 001__ 855 000000855 005__ 20240523045436.0 000000855 02470 $$a10.6082/M11R6NMX$$2doi 000000855 037__ $$aTHESIS$$bDissertation 000000855 041__ $$aeng 000000855 245__ $$aFeshbach and Efimov Resonances in a 6Li-133Cs Atomic Mixture 000000855 260__ $$bUniversity of Chicago 000000855 269__ $$a2017 000000855 300__ $$a161 000000855 336__ $$aDissertation 000000855 502__ $$bPh.D. 000000855 542__ $$fCC BY 000000855 590__ $$aThis thesis reports measurements of interactions in Fermi-Bose 6Li-133Cs mixtures. Precise control of this Bose-Fermi mixture allowed us to probe few-body physics in regimes which were previously inaccessible. In particular, we performed the first model-independent test of geometric scaling of Efimov physics and probed Efimov resonances farther in the weakly coupled, narrow resonance regime than previously possible.,For this work, we built a new apparatus which overcomes the many challenges faced by Li-Cs mixtures. We developed several novel dipole trapping schemes which overcome the difficulties of mixing Li and Cs, including the large differences in initial trapping and cooling between these atomic species and a large differential gravitational sag. We also achieved part per million level magnetic field control near 900 G, necessary for the precise measurements near narrow Feshbach resonances undertaken in this thesis, by pioneering a tomographic magnetic field calibration technique.,With this apparatus, we first probed the Feshbach resonances of the Li-Cs mixture. This is an essential first step, allowing us to understand and control the two-body interactions between our atoms. Next we began to probe Efimov physics, an important three-body phenomenon wherein an infinite series of three-body bound states arise near two-body scattering resonances, such as Feshbach resonances. We demonstrated the universal scaling expected theoretically for Efimov states near a Feshbach resonance. This task was made feasible in our system by a reduced Efimov scaling constant, yet still required precise magnetic field control. Finally, additional universal behavior of the first Efimov resonance has been observed empirically in a variety of atomic systems. While theory has explained this observed universality, predictions also indicate departures for narrow Feshbach resonances, contrary to previous experimental results. By further improving our magnetic field control to probe a very narrow Feshbach resonance, we have observed a departure from the universal first Efimov resonance, helping to resolve this conflict between experiment and theory. 000000855 653__ $$aEfimov physics 000000855 653__ $$aAtomic mixtures 000000855 653__ $$aFew-body physics 000000855 653__ $$aFeshbach resonances 000000855 690__ $$aPhysical Sciences Division 000000855 691__ $$aPhysics 000000855 7001_ $$aJohansen, Jacob$$uUniversity of Chicago 000000855 72012 $$aCheng Chin 000000855 8564_ $$92e6c9616-aa7c-4cc1-af91-9cd2a3bacbeb$$ePublic$$s7182594$$uhttps://knowledge.uchicago.edu/record/855/files/Johansen_uchicago_0330D_13820.pdf 000000855 902__ $$ahttp://hdl.handle.net/11417/609 000000855 903__ $$aMade available in DSpace on 2017-10-02T15:58:36Z (GMT). No. of bitstreams: 1 Johansen_uchicago_0330D_13820.pdf: 7182594 bytes, checksum: 0c60b06427f9516ef62e0a71f09b62cd (MD5) Previous issue date: 1 000000855 909CO $$ooai:knowledge.uchicago.edu:855$$pDissertations$$pGLOBAL_SET$$qthesis_test 000000855 945__ $$aUChicago Dissertations 000000855 945__ $$aPhysical Sciences Division - Dissertations 000000855 946__ $$aUChicago Dissertations 000000855 946__ $$aPhysical Sciences Division 000000855 980__ $$aMIG 000000855 983__ $$aDissertation