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Cavity QED on an Atom Chip

This project hopes to combine the benefits of atoms chips and high finesse optical resonators, two technologies which recently have proven quite useful in ultracold atomic physics.

An atom chip consists of microscopic sized, current carrying wires patterned on some electrically insulating substrate (in our case sapphire or silicon). These wires create magnetic fields which can trap and transport a cloud of cold atoms (in our case ⁸⁷Rb). We are currently fabricating atom chips at the UC Berkeley MicroLab, using a copper electroplating process.

The high finesse optical resonator we have chosen to incorporate is a Fabry Perot type optical cavity. At least one of the mirrors forming the cavity is a slightly curved ultralow loss dielectric mirror on the end of a 3mm diameter glass stock. In the case of the sapphire atom chip, the other mirror is laid directly onto the surface of the chip, and patterned into an ~150um diameter pad (just large enough to fit the entire cavity mode spot). For the silicon chips, a hole is machined through the entire substrate via a Deep RIE Bosch type process, and the cavity is finished with another curved mirror, placed underneath the chip. Sketches of the two chips are shown below. For more information on the usefulness of high finesse cavities in atomic physics see the Cavity QED Lab.