In a collaboration with Prof. Michael Chapman's group at Georgia Tech, we are fabricating very small and optically open ion trap structures for eventual integration with high-finesse optical cavities for experiments in strong-coupling cavity-QED with trapped ions. 

Ion trap and optical cavity-QED systems are ideally suited as benign environements for their respective quantum systems.  However, when these two systems are combined, extreme care must be taken to ensure that each system is sufficiently isolated from the other's environement.  Dielectric mirrors are usually insulators at rf frequencies typically associated with the trapping fields, which poses a serious thread to the stability of the ion trap as free charges on the dielectric can produce large offset electric fields.  Conversely, the ion trap acts as an aperture in the optical cavity volume and diffractive losses may degrade the performance of the cavity.

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Our initial approach is to combine the two systems with a "double endcap" quadrupole trap geometry consisting of two needlepoints mounted on a stage that allows the trap electrode gap to be continuously varied between <20 microns and 1 mm.  A Fabry-Perot cavity with spacing between 0.1 and 1 mm will be installed around this trap.

The smallest ion trap ever demonstrated: a single Cd⁺ ion trapped between two tungsten needle points

This project is supported by the NSF ITR program.