We sucessfully prepared a tunable quantum system consisting of one to ten fermions. We prepare such a system using ultracold Lithium atoms in a micrometer sized optical dipole trap. Due to Pauli's principle one quantum state in the trap is occupied with one atom per spin state (red and blue balls). By tilting the trap we can control the number of remaining quantum states and thus the number of particles.
Schematic preparation scheme of the tunable few-fermion system
The paper is published in the current issue of Science. The ArXiv version can be found here and there is also a press release (in German) by the University of Heidelberg.

The ultracold quantum gases group proudly present its new bubble chamber implemented at the Max-Planck Institute. Due to space constraints it has been temporarily placed inside Selim's office.

Experimental Setup

First Event

Philipp Simon recently handed in his diploma thesis, which further characterizes the new MOT and Zeeman slower and can be found here:

diplomarbeit_philipp.pdf.

We have associated an univeral three-body bound state, so called Efimov state, and measured its binding energy as a function of interaction strength with radio-frequency spectroscopy.
The paper has been published in the current issue of Science. The arxiv version can be found here.

Signal of the trimer association (red points) for different interaction strengths.

The new MOT
We recently finished the construction of a new magneto-optical trap (MOT). With loading rates of 3·10^8 and higher, it will serve as a fast and efficient precooling stage for future experiments. The background collision limited lifetime of atoms in the trap is approximately 23 minutes.

More details on the apparatus can be found in Martin Ries' diploma thesis, which was handed in recently. It is now available online: diplomarbeit_martin.pdf.

We have conducted a study of atom-dimer scattering in an ultracold three-component Fermi gas consisting of 6Li atoms in three different hyperfine states |1>,|2> and |3>.
For this we have prepared three different mixtures of atoms and dimers and observed their decay via inelastic atom-dimer collisions. In the |1>-|23> atom-dimer mixture we have observed resonant enhancement of the loss at the crossings of two Efimov-like trimer states with the |1>-|23> atom-dimer threshold. We have also found that these trimer states can cause a suppression of |3>-|12> → |1>-|23> exchange reactions in the |3>-|12> mixture, which allows to control the rate constants for these processes.
For more details on these results see arXiv:1003.0600

Two-body loss coefficient of the I1>-I23> mixture vs. magnetic field: the red line is a fit according to universal theory..

Congratulations Timo!
The thesis is available here:
Few-body physics in ultracold Fermi gases

Recently Gerhard Zürn handed in his diploma thesis which is about the
"Realization of an Optical Microtrap for a Highly Degenerate Fermi Gas" .
It is now available online: thesis-gerhard.pdf.

In the last few weeks we accomplished another milestone on our way to a mesoscopic Fermi system the realization of a small volume optical dipole trap with high trapping frequencies ("microtrap"). More information will be provided in the diploma thesis of G. Zürn which will appear in a few weeks.

Shown is the optical density of the large volume dipole trap (a), the transfer between dipole trap and microtrap (b) and only the microtrap (c).