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Q: Fachverband Quantenoptik und Photonik

Q 56: Poster IV

Q 56.23: Poster

Donnerstag, 5. März 2009, 16:30–19:00, VMP 9 Poster

Superconducting atom chips: parameters and properties — •Bo Zhang and Carsten Henkel — Universität Potsdam, Institut für Physik und Astronomie, Karl-Liebknecht-Str. 24/25, 14476 Potsdam, Germany

Atom chips provide small and robust traps for ultracold atoms at the microKelvin and below. However, the ‘hot’ chip surface strongly perturbs the trapped atoms. This can be avoided with superconducting atom chips where thermal magnetic noise and thechnical noise are significantly reduced. Superconducting wires show inhomogeneous current distributions, however, that have to be computed self-consistently, taking into account the screening of external bias fields. We investigate magnetic traps produced by wires in the Meissner and mixed (Shubnikov) state, with arbitrary cross-sections, using boundary integral equations in numerics and conformal mappings. The trap parameters and properties are discussed and compared to metallic atom chips. It is well known that temperature, magnetic field and current density must stay below certain critical values, otherwise the superconductivity breaks down: type I superconductors transit into a normal conductor, while type II SC transit into the mixed state (penetration of vortices). We analyze how this constraint imposes critical transport currents and bias fields for selected atom chip geometries.