Surface-electrode point Paul trap

We present a model as well as experimental results for a surface electrode radiofrequency Paul trap that has a circular electrode geometry well suited for trapping single ions and two-dimensional planar ion crystals. The trap design is compatible with microfabrication and offers a simple method by which the height of the trapped ions above the surface may be changed in situ. We demonstrate trapping of single ⁸⁸Sr{}⁺$ ions over an ion height range of $200{-}1000$ ${μ}$m for several hours under Doppler laser cooling and use these to characterize the trap, finding good agreement with our model.