A Free Space Fabry-Perot Cavity with a Submicron Mode Waist

Programmable tweezer arrays and cavity QED are two platforms with distinct yet potentially complementary advantages for quantum information science. Interfacing these two systems has thus far been an outstanding challenge. We have developed a new type of Fabry-Perot resonator with tweezer-like properties – a so-called "small-waist" cavity. Utilizing a submicron-mode waist for efficient single atom trapping and high cooperativity, such a device promises to dramatically lower the finesse requirements (to as low as 60) in the field of cavity QED with strong coupling. This opens a new paradigm of optical elements integrated into such resonators and even out-of-vacuum cavities around glass cells. We overview the challenges of designing such a cavity from the perspective of stability and summarize recent experimental progress towards demonstrating strong-coupling in the small-waist regime.