An apparatus for millimeter-wave-mediated quantum gates between Rydberg atoms

Rydberg atom arrays have become a leading platform for quantum computing and simulation. However, the power-law decay of the interaction strength in Rydberg systems poses a limitation to efficient generation of long-range entanglement, as compared to the non-local interactions achievable between trapped ions or cold atoms in optical cavities. We propose to trap Rydberg atoms in a millimeter (mm)-wave Fabry-Perot cavity to enable high-fidelity non-local entangling gates. Coupling a transition between circular Rydberg states to a cavity mode will enable atoms to interact with each other regardless of their locations, by emitting and reabsorbing photons to and from the cavity mode. We are developing a high-finesse superconducting cavity with optical access for atom trapping and single-atom detection in a cryogenic apparatus. This new platform will enable entangling gates between atom pairs separated by mm-scale distances, as well as scalable preparation of many-body entangled states. The platform also offers opportunities in quantum simulation, with the interplay of local dipolar and global cavity-mediated interactions raising prospects for accessing novel strongly correlated states.