Superconducting Switch for Fast On-Chip Routing of Quantum Microwave Fields

For a quantum computer, switching a signal carried by single microwave photons is desirable in scaling up superconducting circuitry. The authors design and build such a switch, integrate it on a chip with a single-photon source, and prove that it works with nonclassical microwave input. Their device offers negligible heating, relatively large bandwidth, low nonlinearity, and single-pole double-throw switching in mere nanoseconds. It is well suited for applications where signal routing must be controlled by real-time feedback, as in multiplexing qubit control and readout, or distributing entanglement in quantum networks.