Welcome to the Ultracold Quantum Gases Group at the Physikalisches Institut of the Ruprecht-Karls-Universität Heidelberg

Our research is focused on ultracold Fermi systems. For more information, please read about our project! If you would like to know more, or if you have some comments or ideas, please don't hesitate to contact us!

Imaging with matter-wave Fourier optics

In our recent paper published in Physical Review A (also available at arXiv:1408.4680), we describe a simple technique to measure the momentum distribution of a strongly interacting quantum gas. We have used well known concepts from Fourier optics to investigate three operations on the gas: focusing, collimation and magnification. When we apply these techniques in our experiment, we see a prominent occupation of low momentum states that was not visible in the in-trap density distribution.

Master's thesis finished

Sebastian finished his Master's thesis on the BKT-phase transition in a strongly interacting 2d Bose gas. We're very sad to see you go and wish you all the best, Sebastian!

From Few to Many

In our recent paper which was published in the current issue of Science 342, 457 (2013) (also available at arXiv:1307.3443), we study the formation of a Fermi sea one atom at a time. We investigate the crossover from few to many-body physics in a quasi one-dimensional system using a single impurity atom which interacts with an increasing number of majority atoms that are in a different state. We could show that for the investigated quantum impurity systems as few as four particles are enough to describe the system with the many-body theory.

More information can be found in the press release (in English or German) from the University of Heidelberg.

Furthermore, our publication is also discussed and explained for a broader audience, for instance in physicsworld and in a science blog.

Few-Body Systems: Cooler Than You Might Think

Our work on finite fermionic systems was recently covered in a science blog by Chad Orzel. The article nicely summarizes and explains why few-body systems are interesting and what we are able to do with these kind of systems.

Link to the article.

Move to the new PI

In December last year we moved our experiments from the MPIK in Heidelberg to the Physikalisches Institut, also in Heidelberg. In this new building, the rooms for our labs had just been finished before. We decided to keep the optics and vacuum chambers mounted on the tables for the move. This allowed us to start up our experiments quickly: As of now, one experiment is running as good as before the move, the other experiment is steadily getting there.

Retreat in Maria Waldrast with the Grimm group

We just went on a short retreat with the Grimm group from Innsbruck. The two days at the monastry Maria Waldrast in the Austrian alps were full of interesting discussions, beautiful landscapes and nice hiking.

In front of the monastry Maria WaldrastIn front of the monastry Maria Waldrast

Walk in the afternoonWalk in the afternoon

The peopleThe people

Diploma thesis finished

The new BECThe new BEC
Johanna Bohn recently finished her diploma thesis, which describes the setup of our new dipole trap and the molecular BEC we are able to create in this trap.
The thesis can be found here: diplomarbeit_johanna.pdf.

Fermionization of Two Distinguishable Fermions

In our latest paper we make two distinguishable atoms behave as if they were fermions, and verify this by comparing them to two identical fermionic atoms. The paper has been selected as an editor's suggestion by PRL, and was highlighted by a Physics synopsis:
2 distinguishable vs. 2 identical atoms2 distinguishable vs. 2 identical atoms

New paper published

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 systemSchematic 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.