Addressing Individual Persistent Current Switches With a Cryogenic Optical Scanner

We demonstrate a robust and minimalist implementation of individually addressable optically actuated persistent current switches. We use a focused laser beam directed by a cryogenic laser scanner to drive a selected segment of a superconducting loop normal with a pulse of light. We address six distinct switches with a single electrical bias, and use SQUID readout to show that persistent current is trapped successfully. Based on the cryogenic scanner's performance, we argue that this method can address over 60,000 switches, with the full array being set in about one second. Persistent current switches are widely used in quantum circuits, and we expect the ability to set tens of thousands of persistent currents with a single bias line will be useful in many applications.