Im Neuenheimer Feld 226
Tel: 06221/ 54 19471
Fax: 06221/ 54 19545
Quantum dynamics of atomic and molecular systems
Our group studies atomic and molecular quantum systems with respect to their interactions on different levels of complexity. Of special importance is the application and extension of modern methods for the manipulation and quantum control to many-body quantum systems, in particular using coherent light. The systems under investigation range from highly excited Rydberg atoms over atomic and molecular quantum gases to molecular aggregates. The group develops technologies for trapping and cooling of neutral atoms as well as quantum-state sensitive diagnostics.
Latest news from the lab
|Observation of Efimov Resonances in a Mixture with Extreme Mass Imbalance published in Phys. Rev. Lett.!||21.07.2014|
Vitaly Efimov predicted already 40 years ago that there is a universal law for any three resonantly interacting particles and that this law has a discrete scaling behavior, i.e. that the resonances appear on a regular basis. We started with an ultracold gas of Li and Cs at temperatures as low as 400 nK and held the strongly interacting mixture in an optical dipole trap. By precisely changing the external magnetic field near a so-called Feshbach resonance, where the interaction energy between Li and Cs is tunable, we let the atoms interfere with several three-body bound states of the underlying scattering resonance. When the Efimov resonance is hit, the atoms experience an enhanced three-body loss and we record the three-body loss rate by a time-resolved measurement of the atom number. The scaling factor between resonances depends on the mass ratio, for which we measure a value of 5 from the series of resonances in good agreement with the theoretical prediction. While the ground Efimov state is about 50 nm in size, the 2nd excited Efimov state is very large with a length scale of almost one µm.
Observation of Efimov Resonances in a Mixture with Extreme Mass Imbalance, Phys. Rev. Lett. 112, 250404 (2014), or see our full list of publications
|Double degeneracy of Li and Cs in the mixtures lab!||1.3.2014|
Li is loaded directly after magneto-optical trapping into the crossed dimple trap at 140 W provided by an Yb fiber laser. Forced evaporation at 690 G leads to about 120000 atoms at 230 nK before the laser power is finally ramped down to values between 80 and 230 mW at which the bimodal distribution is visible. After Cs atoms are captured in a magneto-optical trap they are cooled by degenerate Raman side-band cooling into a reservoir trap. Before the final evaporation about 85000 Cs atoms are transferred into the dimple trap and Bose-Einstein condensation is reached for final laser powers between 130 and 150 mW.
|German-Japanese Colloquium on Frontiers of Laser Science organised by Humboldt awardee Kenji Ohmori and Matthias Weidemüller||16.01.2014|