Mainz 2017 – scientific programme

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A: Fachverband Atomphysik

A 15: Ultracold atoms and BEC - III (with Q)

A 15.4: Talk

Tuesday, March 7, 2017, 15:15–15:30, N 1

The Bose polaron in an ultracold Bose-Fermi mixture of Cs and Li — •Stephan Häfner, Binh Tran, Manuel Gerken, Melina Filzinger, Bing Zhu, Juris Ulmanis, and Matthias Weidemüller — Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany

An ultracold Bose-Fermi mixture of ¹³³Cs and ⁶Li is well suited for the investigation of the Bose polaron. In this scenario a single Li impurity is immersed in a Cs BEC and interacts with its phonon excitations, mimicking the Fröhlich polaron problem from solid-state physics. Tuning the sign and strength of the interaction between Li and Cs via Feshbach resonances enables us to study repulsive and attractive polarons. The observation of different polaron states, ranging from the Landau-Pekar polaron to the bubble polaron is within reach for the Li-Cs system.

In this talk we describe the production of a Cs BEC by forced evaporative cooling in an optical dipole trap. The phase-space density is enhanced by modifying the trapping geometry with an additional small-sized dipole trap. This is the first step for the study of the Bose polaron in the Li-Cs system.