A switch for qubits handles 100 picowatts of readout power

Ziyi Zhao from JILA, National Institute of Standards and Technology, and the University of Colorado Boulder, along with colleagues, has designed a new superconducting switch capable of handling more than 100 pW of readout power—a crucial step toward scaling quantum processors. The switch utilizes a stable persistent current associated with tens of flux quanta, minimizing the need for constant recalibration and reducing static power consumption. This design addresses a key limitation in current quantum systems by employing direct current actuation, which reduces potential crosstalk between densely integrated qubits and facilitates more modular cryogenic measurements. The work demonstrates a switch with over 20 dB isolation, comparable to commercial ferrite isolators,…