Ruprecht Karls Universität Heidelberg

Experiments on three-component Fermi gases

Recently we managed to prepare a three-component degenerate Fermi gas of 6Li with 50000 atoms in each state at a temperature of 215 nK, which corresponds to T/TF=0.37.
We studied the collisional stability of the gas in the magnetic field range from 0 to 750 G and found a broad and pronounced loss feature at 130 G. At approximately 580 G the sample remains quite stable, with 1/e lifetimes exceeding 30 s.
a.) Magnetic field dependence of the remaining fraction of a three-state mixture
		b.) two-component mixture as a reference
		c.) scattering lengths in all possible channels
a.) Magnetic field dependence of the remaining fraction of a three-state mixture
b.) two-component mixture as a reference
c.) scattering lengths in all possible channels

For a more quantitative analysis we deduced the three-body loss coefficient K3 from lifetime measurements.
The new results are available at arXiv:0806.0587.



now it’s ultracold: Our first molecular BEC!

We have reached condensation of 80000 6Li2 molecules in a dipole trap using an all-optical approach.
After being precooled in our magneto-optical trap (MOT) the 6Li atoms are transferred into the optical dipole trap, for which we use a 200 W fibre laser. The trap is established by two focussed beams with a waist of 50 µm crossing under an angle of about 7°.

Our first molecular BEC
Our first molecular BEC

Picture: Bimodal (condensate and thermal cloud) distributions at different stages of evaporation with final laser power between 120 - 61 mW. Before taking the image (after a time of flight of 10ms) the laser power is adiabatically ramped back to 120mW for all images.



second diploma thesis finished

the second diploma thesis (from Thomas Lompe) with the title:
"An apparatus for the production of molecular Bose-Einstein condensates"
was just finished. And is now available online:
diplomarbeit-thomas



diploma thesis finished

The first diploma thesis with the title
"The setup of a Magneto Optical Trap for the preparation of a mesoscopic degenerate Fermi gas"
is now online.
diplomarbeit-friedhelm



first atoms trapped

a further step towards a molecular BEC could be reached: The Magneto Optical Trap (MOT)

fluorescence of the trapped atoms
fluorescence of the trapped atoms


mot after some feeding
mot after some feeding


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