# Heidelberg 2015 – wissenschaftliches Programm

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# Q: Fachverband Quantenoptik und Photonik

## Q 12: Quantum Gases: Bosons II

### Q 12.8: Vortrag

### Montag, 23. März 2015, 16:15–16:30, P/H2

**Bose Polaron in a Harmonic Trap** — •Artem Volosniev^{1,2}, Hans-Werner Hammer^{2}, and Nikolaj Zinner^{1} — ^{1}Aarhus University, Aarhus 8000, Denmark — ^{2}TU Darmstadt, Darmstadt, Germany

The study of an ideal system with an impurity dates back to the dawn of quantum theory. This so-called polaron problem has allowed physicists to develop sophisticated mathematical tools for many-body problems that in turn were used to gain insight in both static and dynamics properties of systems with impurities. Originally formulated in condensed matter physics this problem has become a hot topic in the community working on cold atomic gases.

In this contribution we present a field-theoretical study of an impurity immersed in an ideal harmonically trapped Bose Gas at zero temperature. A method to calculate the Green's function in space-time and momentum-time domain is developed for times much smaller than the time scale set by the external trap. Comparing these functions with the solutions for the homogeneous case the effect of an external trap is discussed.