Millimeter-wave resonator and associated methods

A millimeter-wave resonator is produced by drilling a plurality of holes into a piece of metal. Each hole forms an evanescent tube having a lowest cutoff frequency. The holes spatially intersect to form a seamless three-dimensional cavity whose fundamental cavity mode has a resonant frequency that is less than the cutoff frequencies of all the evanescent tubes. Below cutoff, the fundamental cavity mode does not couple to the waveguide modes, and therefore has a high internal Q. Millimeter waves can be coupled into any of the tubes to excite an evanescent mode that couples to the fundamental cavity mode. The tubes also provide spatial and optical access for transporting atoms into the cavity, where they can be trapped while spatially overlapping the fundamental cavity mode. The piece of metal may be superconducting, allowing the resonator to be used in a cryogenic environment for quantum computing and information processing.