A Josephson sampler with 2.1 ps resolution

A Josephson sampler with 2.1 ps resolution is reported. The sampler was made with Nb edge junctions, and consists of a sampling junction to which a Faris pulser is coupled directly. Two experiments are connected to the sampler: a two-junction interferometer and another Faris pulser. A new and simple electronic delay allows a flicker-free display on an oscilloscope of the waveform sampled. A current sensitivity of 0.8 μA was achieved. It was possible to measure the switching transitions of the two-junction interferometer over its whole vortex boundary, including vortex-to-vortex transitions which occur at low bias currents. To our knowledge, this is the fastest Josephson sampler made to date.