SQUIDs and Transition-Edge Sensors

In 1988, I begin as a graduate student in Blas Cabrera’s group at Stanford University. I was drawn by the group’s focus on fundamental physics questions using a sensitive new type of detector: the superconducting transition-edge sensor (TES). However, these sensors had important flaws. They were unstable, they were slow, and they could not be made to work in arrays. I describe the discovery as a graduate student that the Josephson Junction, and the SQUID amplifier it enables, changes all of that. This discovery has led to generations of science with dark matter detectors, x-ray spectrometers, and cosmic microwave background experiments.