Supplementary information is presented on the recent work by Moonjoo Lee et al. on the sub-wavelength 3D imaging of the vacuum-field intensity in a cavity by using single atoms confined by a nanohole aperture as a nanoscopic probe.
When an excited atom is placed in a high-Q cavity, it is driven by the cavity vacuum field at its position and emits a photon into the cavity mode. Based on this principle, we have performed 3D imaging of the vacuum field in a Fabry-Perot cavity. Atomic position localization is achieved by using a nanohole-array atom-beam aperture scannable in front of the cavity mode. The transit-time broadening in the atom-cavity detuning curve provides the vacuum field profile along the direction of atomic beam. In this way the 3D profile of the vacuum-field intensity is imaged with a spatial resolution of about 170 nm, which is mostly limited by the nanohole diameter.
We report a high-finesse bow-tie cavity designed for atomic physics experiments with Rydberg atom arrays. The cavity has a finesse of 51,000 and a waist of 7.1 μm at the cesium D2 line (852 nm). With these parameters, the cavity is expected to induce strong coupling between a single atom and a single photon, corresponding to a cooperativity per traveling mode of 35 at the cavity waist. To trap and image atoms, the cavity setup utilizes two in-vacuum aspheric lenses with a numerical aperture (NA) of 0.35 and is capable of housing NA = 0.5 microscope objectives. In addition, the large atom-mirror distance (≳1.5 cm) provides good optical access and minimizes stray electric fields at the position of the atoms. This cavity setup can operate in tandem with a Rydberg array platform, creating a fully connected system for quantum simulation and computation.