Microfabrication of gold wires for atom guides

Miniaturised atom optics is a new field allowing the control of cold atoms in microscopic magnetic traps and waveguides. Using microstructures (hereafter referred to as atom chips), the control of cold atoms on the micrometer scale becomes possible. Applications range from integrated atom interferometers to the realisation of quantum gates. The implementation of such structures requires high magnetic field gradients. The motivation of this work was to develop a suitable fabrication process for micromachined high-density current-carrying wires for atom guides. However, the developed process may be used for a variety of applications such as on-chip inductors and microtransformers. In order to realise the micromachined wires for atom guides different designs and fabrication processes were investigated. We discuss the feasibility and the suitability of the fabrication process based on gold sputtering technique to realise such devices. As an alternative we have considered a lower cost technique based on gold electroplating. For the electroplating we used commercial full bright cyanide free gold plating solution (gold sulphite, mild alkaline solution with pH = 9 Gold ECF 60, brightener E3) containing 10 g/dm(3) gold from Metalor. Some analytical and measurement results of magnetic atom traps are also presented in this paper. (C) 2004 Elsevier B.V. All rights reserved.