Adjustable Microchip Ring Trap for Cold Atoms and Molecules

We describe the design and function of a circular magnetic waveguide produced from wires on a microchip for atom interferometry using de Broglie waves. The guide is a two-dimensional magnetic minimum for trapping weak-field seeking states of atoms or molecules with a magnetic dipole moment. The design consists of seven circular wires sharing a common radius. We describe the design, the time-dependent current of the wires and show that it is possible to form a circular waveguide with adjustable height and gradient while minimizing perturbation resulting from leads or wire crossings. This maximal area geometry is suited for rotation sensing with atom interferometry via the Sagnac effect using either cold atoms, molecules and Bose condensed systems. The original document contains color images. All DTIC reproductions will be in black and white. Published in the Journal of Physical Review A v80 n6 2009. 1050-2947. Sponsored in part by DARPA and AFOSR.