Measurement using a current-axis-independent Josephson sampler

Abstract
We have improved measurement of the current‐axis‐independent Josephson sampler. We use a new chopping detection circuit in the feedback system for sampling point control. Two channels of the sampling head are utilized to cancel drift in the time base. Drift is about 3 ps. We have measured the output of a short pulse generating circuit and obtained a transition duration of 15 ps.