Tunable coupling between superconducting 3d cavities via integrated low-loss couplers on a planar circuit

Modular quantum networks consisting of superconducting circuits are a promising approach to processing large scale quantum information tasks. To utilize the high quality factor 3-dimensional microwave cavities as the memory component within the modules, an ongoing challenge is to implement rapid, reconfigurable, and low-loss swap interactions among the cavities. One approach is to interface the cavities with a planar circuit to mediate the interaction, on which the switching elements can be tuned to change the coupling strength. This leverages the design flexibility and large-scale manufacturability of planar circuits to allow for more suitable and better performing switching elements.



In the talk, we’ll describe the design and show preliminary data for a tunable coupling scheme between 3d superconducting microwave cavities mediated by switching elements on a planar circuit. Both the 3d cavities and the planar circuit are made monolithically, and they are coupled seamlessly to eliminate seam losses in the microwave signal lines. This coupling is achieved by superconducting loops collecting magnetic flux from the cavities, and the propagating mode is kept balanced throughout.