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A: Atomphysik

A VI: HV VI

A VI.1: Hauptvortrag

Dienstag, 5. März 2002, 12:20–13:00, HS 22/B01

Fundamental limits for coherent manipulation on atom chips — •Carsten Henkel¹ and Peter Krüger² — ¹Institut für Physik, Universität Potsdam, D–14469 Potsdam — ²Physikalisches Institut, Universität Heidelberg, D–69120 Heidelberg

Miniaturization is expected to enhance the potential of atom optics, as did the integration of electronic circuits. Atom chips currently trap atoms a few micrometers above a structured substrate using electric currents, charges or micromagnets. In these small devices, thermal or technical noise generates electromagnetic field fluctuations and reduces the trap lifetimes and the atomic coherence. We focus here on magnetic traps based on wires and investigate the fundamental limits imposed by current shot noise. Estimates show that shot noise does play a role for atoms in µm-sized traps and limits their lifetime on a timescale of seconds. We discuss the 3D magnetic field geometry in chip traps and identify strategies to reduce loss and decoherence rates. Preliminary measurements indicate that current noise is yet above the shot noise level and may explain the observed loss of a trapped cloud (D. Cassettari, Ph.D. thesis, University of Innsbruck 2000).