Progress Towards a Quantum Degenerate Mixture with Extreme Mass Imbalance

B. J. DeSalvo, Krutik Patel, Jacob Johansen +1 more

Yoshiro Takahashi, Schaefer Florian, N. Mizukami

Krutik Patel, B. J. DeSalvo, Geyue Cai +1 more

M. Iskin, Carlos A. R. Sá de Melo

Tommaso Roscilde, Marcello Dalmonte, C. Degli Esposti Boschi

R. Pires

This thesis reports on the investigation of few-body physics in an \nultracold mass-imbalanced mixture at large scattering lengths. For this purpose, a \nnew apparatus for the creation of quantum degenerate 6Li and 133Cs gases has been \nbuilt. We measure 19 interspecies Feshbach resonances in the two energetically lowest \nhyperfine channels of each species of an ultracold mixture with temperatures on \nthe uK scale. We apply and compare a coupled-channels calculation, the asymptotic \nbound-state model, and the multichannel quantum defect theory for the calculation \nof the Feshbach resonance positions. All models provide a consistent and accurate \ndescription of the two-body scattering resonances in the mixture. Three-body loss \nrate measurements on the negative scattering length side of a broad Feshbach resonance \nin the energetically lowest hyperfine channel at 450 nK reveal two consecutive \nEfimov resonances. The scattering lengths assigned to the two Efimov resonances \nyield a scaling ratio that is consistent with a universal prediction in the zero temperature \nand resonant limit. The presented measurements provide the first test for \nuniversal few-body theories of mixed-species systems with large mass-imbalance.