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

Rydberg atom arrays have become a leading platform for quantum science, but the locality of Rydberg interactions limits the efficient generation of long-range entanglement, as compared to the nonlocal interactions achievable between trapped ions or cold atoms in optical cavities. We present progress toward trapping Rydberg atoms in a superconducting millimeter-wave Fabry–Pérot cavity to enable high-fidelity nonlocal 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 an effective cavity-mediated interaction. A superconducting cavity with finesse 6 × 10⁷ at 1 K and high optical access (numerical aperture 0.56) promises highly coherent atom–photon interactions for single-atom trapping and imaging, while realization of ordered arrays of Rydberg atoms in a separate room-temperature system provides a testbed for the local control required for the hybrid atom–cavity platform. This new apparatus will enable realization of entangling gates between atom pairs separated by millimeter distances, scalable preparation of many-atom entangled states, and exploration of strongly correlated phases arising from the interplay of local and global interactions.