Multiplexed readout of superconductor–normal-conductor–superconductor bolometers

Abstract

Recently, ultrasensitive calorimeters have emerged as a resource efficient solution for different applications, such as qubit readout, radiation sensors, etc. Multiplexing these detectors paves the path for a larger range of usage. However, experiments demonstrating frequency multiplexing of these superconductor–normal-conductor–superconductor (SNS) sensors are lacking in the literature. To this end, we present the design, fabrication, and operation of three SNS sensors with frequency-multiplexed input and probe circuits, all on a single chip. These devices have their probe frequencies in the range of 150–200 MHz, which is well detuned from the heater frequencies of 4.4–7.6 GHz compatible with typical readout frequencies used in different applications in microwave physics. Importantly, we show on-demand triggering of both individual and multiple low-noise SNS bolometers with minimal cross talk. These experiments pave the way for multiplexed bolometric characterization and calorimetric applications.