Spin-specific trapping and mechanical control of ultracold atoms is difficult with current techniques, but offers the possibility of exploring new physics systems, such as spin-dependent trapped atom interferometers, as well as quantum gates, 1D many-body spin gases, and novel cooling schemes. Microwave near-field potentials based on the AC Zeeman effect provide a mechanism for such spin-specific control of atoms: in principle, independent potentials can be targeted to different spin states simultaneously. A broadband microwave atom chip can be used to generate both AC Zeeman trapping potentials and a microwave lattice for long distance trap positioning. We present recent experimental results on the successful trapping of ultracold rubidium atoms in an AC Zeeman atom chip trap using RF intra-hyperfine manifold transitions. Notably, these traps suppress the potential roughness encountered in traditional micro-magnetic chip traps.
In its most general form, the atom chip is a device in which neutral or charged particles are positioned in an isolating environment such as vacuum (or even a carbon solid state lattice) near the chip surface. The chip may then be used to interact in a highly controlled manner with the quantum state. I outline the importance of material science to quantum computing (QC) with atom chips, where the latter may be utilized for many, if not all, suggested implementations of QC. Material science is important both for enhancing the control coupling to the quantum system for preparation and manipulation as well as measurement, and for suppressing the uncontrolled coupling giving rise to low fidelity through static and dynamic effects such as potential corrugations and noise. As a case study, atom chips for neutral ground state atoms are analyzed and it is shown that nanofabricated wires will allow for more than
104 gate operations when considering spin-flips and decoherence. The effects of fabrication imperfections and the Casimir-Polder force are also analyzed. In addition, alternative approaches to current-carrying wires are briefly described. Finally, an outlook of what materials and geometries may be required is presented, as well as an outline of directions for further study.