Workgroup Prof. Artur Widera

Ultracold fermionic superfluids

Ultracold fermionic quantum gases are ideal model systems to investigate complex phenomena of quantum physics – such as superconductivity in solids – in a well controlled environment. We aim on a better understanding of how various superfluid quantum states behave in in externally and dynamically controlled environments. Particularly, we want to understand how controlled impurities allow manipulating the properties of a superfluid system.

Cooling and trapping of atoms

Lasers can be used to trap, manipulate and cool atoms down close to absolute zero temperature. For precise control of laser beam properties, complex optical systems are needed. The experiments are performed in an ultra-high vacuum environment to isolate the atomic gases used from the surrounding room-temperature air.

Suprafluids in the lab

At ultracold temperatures below one millionth degree above absolute zero, quantum effects dominate the behaviour of cold atoms. In particular we are interested in so called superfluids: liquids which flow frictionless. Such a behaviour can be observed in superconductors, which conduct electric current without loss.

Controlled interactions

Strong magnetic fields allow us to manipulate the interaction between ultracold atoms and switch between attraction and repulsion. This facilitates, for instance, the observation of the transition from a superfluid (like in a superconductor) to a molecular Bose-Einstein condensate.

Behaviour in disordered potentials

Most physical systems are not as perfect as often assumed in models, but disordered. The phenomenon of Anderson localization illustrates the potentially strong impact this might have: if the degree of disorder crosses a threshold, particles can no longer move but are localized to some region in space. We want to study this effect by exposing the fermionic quantum gas to a disordered potential landscape and investigate transport properties.

Experimentally, we examine the interaction of the quantum gas with different potential landscapes, which are created by external light fields and/or an additional atomic species.

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