Abstract

We report the laser cooling and trapping of barium ions in a novel planar Paul trap. Unlike other rf quadrupole traps, the electrodes of a planar Paul trap are confined to one or more parallel planes. They may therefore be constructed on a micrometer scale by the same photolithographic techniques used for semiconductor devices. Such devices are under construction in our laboratory. 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. Our traps consist of one or more parallel planes, one above the other, each plane having either a conducting ring or a hole in a conducting sheet. Thus, a ring or a hole results in a potential well for trapping. A three-ring design produces a quadrupole potential that is harmonic up to eighth-order for a particular choice of ring diameters and spacings. Three-hole traps have been constructed with inner hole radii ranging from 50 to 400 μm, and both single barium ions and clouds have been observed.

© 1992 Optical Society of America