Hannover 2016 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 55: Ultra-cold atoms, ions and BEC IV (with A)

Q 55.5: Talk

Thursday, March 3, 2016, 15:30–15:45, f303

Single particle dynamics in an ultracold environment: From superfluidity to finite size reheating — •Paula Ostmann and Walter Strunz — TU Dresden, Inst. f. Theor. Physik, Zellescher Weg 17, 01062 Dresden

We investigate the quantum dynamics of a single ion which is immersed into a Bose-Einstein condensate. The ultracold environment acts as a refrigerator, and thus, the influence on the motion of the ion is dissipative. For a theoretical description, simple phenomenological master equation approaches are widely used to describe the ensuing damped quantum dynamics. Instead of calculating the particle dynamics itself, our focus lies on a more detailed description of the environment and the particle-environment interaction. We aim to describe the effective dynamics of the damped particle dynamics using the full bath correlation function instead of a simple damping rate. In this way we gain a more thorough theoretical understanding of properties of quantum matter, such as superfluidity, when acting as an environment.

We find that we can divide the dynamical effect of the BEC on the ion into two parts: The initial energy loss and the return of energy to the ion dynamics. By considering just the initial decay we effectively study an ion coupled to an infinitely large environment and are able to identify a Landau Criterion for a quantum particle in a harmonic trap. Secondly we see that the finite size of the condensate causes the return of the energy, which results in a periodically reheating of the ion, which could be used as an additional cooling mechanism as well.