Small-Waist Cavities Part 1: Cavity Enhanced Atom Detection

We introduce a new class of optical resonator, of extremely small waist and low-finesse, that offers all of the advantages of more traditional large-waist/high- finesse cavities, while significantly lowering the overall technical overhead. We demonstrate cooperativity > 1; linewidth of many MHz; and a submicron waist compatible with integration into an atom-array quantum computer, all at a finesse < 100 that allows for the cavity end-mirrors to be outside of vacuum and for the introduction of intracavity nonlinear and/or adaptive optics. Harnessing this submicron-waist resonator, we demonstrate single atom trapping by parity projecting directly into the cavity mode, and then demonstrate cavity enhanced detection. This work paves the way to a future where high cooperativity cavities & arrays are routinely integrated into next-generation quantum technology.