Planar Paul traps and trap arrays

We report the cooling and trapping of barium ions in a novel planar Paul trap. Unlike other if quadrupole traps, the electrodes of a planar Paul trap are confined to one or more parallel planes. We apply the same photolithographic techniques used for semiconductor devices to construct inicrotraps with dimensions on a micron scale. Micro traps permit entirely new studies, for example, superradiance of a few ions, which occurs as ion-ion distances approach one wavelength of light. Photolithography can also generate an array of traps on a single substrate for an atomic clock, where each trap contains a single isolated ion in the Lamb-Dicke regime, resulting in a high signal-to-noise ratio. This achieves the same goal as a linear rf trap1 but without any coupling between the ions.