Berlin 2014 – scientific programme

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A: Fachverband Atomphysik

A 34: Poster: Ultra-cold atoms, ions and BEC (with Q)

A 34.28: Poster

Wednesday, March 19, 2014, 16:30–18:30, Spree-Palais

Single flux quanta observed with ultracold atomic clouds — •Patrizia Weiß, Helge Hattermann, Simon Bernon, Martin Knufinke, Daniel Bothner, Matthias Rudolph, Lörinc Sárkány, Florian Jessen, Petra Vergien, Simon Bell, Reinhold Kleiner, Dieter Koelle, and József Fortágh — Physikalisches Institut and CQ Center for Collective Quantum Phenomena and their Applications, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 14, D-72076 Tübingen, Germany

When superconducting closed loops like a ring are cooled through the superconducting transition (T_c =9.2 K) in an external field, persistent currents will conserve the magnetic flux inside the ring. This trapped flux is quantized and will be an integer multiple of the magnetic flux quantum Φ₀ = 2.067× 10⁻¹⁵ Tm².

We report on the interaction of an atomic cloud with a superconducting ring. We trap atomic clouds of ⁸⁷Rb in a superconducting magnetic microtrap at 4.2 K and bring the atoms into the vicinity of the ring structure (R = 10 µm). The atomic cloud is sensitive to the additional potential generated by the persistent currents in the ring. Changes of single flux quanta Φ₀ can be observed in the atomic density distribution, as well as in the trap shape. The results pave the way towards coupling cold atoms to SQUIDS and the generation of periodic magnetic micropotentials based on persistent currents.

As a further step towards coupling, we will discuss the preparation of cold atomic clouds in a dilution refrigerator [1].

[1] F. Jessen et. al., arXiv:1309.2548