Mainz 2017 – scientific programme

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A: Fachverband Atomphysik

A 20: Poster Session I

A 20.4: Poster

Tuesday, March 7, 2017, 17:00–19:00, P OG1

Towards a Bose polaron in an ultracold Fermi-Bose mixture of ⁶Li and ¹³³Cs — •Binh Tran, Stephan Häfner, Manuel Gerken, Melina Filzinger, Bing Zhu, Juris Ulmanis, and Matthias Weidemüller — Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg

In our experiment we are working towards the creation of a Bose polaron in an ultracold Bose-Fermi mixture of ¹³³Cs and ⁶Li atoms with a large mass imbalance. The Bose polaron is a quasiparticle that describes a single Li impurity which is immersed into a Cs BEC and interacts with its phonon excitations. Therefore, this scenario is similar to the Fröhlich polaron from condensed matter physics. Via Li-Cs Feshbach resonances we can tune the interparticle interaction strength and change the sign of interaction, thus enabling us to investigate both attractive and repulsive polarons.
We describe the creation of a Cs BEC by means of evaporative cooling in an optical dipole trap, after the atoms have been brought to a temperature of around 1 µ K in previous cooling stages. In order to reach a high phase-space density we modify our trapping potential by adding a second dipole trap with a smaller waist and applying two consecutive evaporation steps. Furthermore, we give an overview of our approach towards the experimental investigation of the Bose polaron, its energy spectrum and dynamic properties.