Single atom cavity scanning microscope

Cavity QED provides a powerful set of tools for manipulating atomic systems, facilitating weak and strong measurements of different atomic observables and enabling long-range interactions by the exchange of real or virtual cavity photons. Ultimate control of these interactions requires accurate positioning of individual atoms relative to the cavity field. We present a novel cavity QED system of a tweezer array of single rubidium atoms trapped in a high finesse near-concentric optical cavity. Individual atom-cavity couplings are controlled by tuning tweezer position, and single atoms are imaged with high fidelity through a high numerical aperture (NA=0.5) objective transverse to the cavity. In this work, we measure cavity fields of different wavelengths (780 and 1560nm) and spatial structure (TEM₀₀ and TEM₀₁ Hermite-Gaussian modes) by detecting the AC Stark shift they impose on the atoms, manifested in the fluorescence imaging scattering rate. This measurement provides a detailed characterization of the modes supported by the optical cavity. The single-atom control demonstrated in this work serves as a basis for implementing cavity-assisted long-range interactions and measurement and paves the way to exploring correlated many-body states in optical cavities at the single-atom level.