Ultra high resolution Josephson sampling technique

摘要

A circuit is provided for sampling and accurately reproducing unknown signals with picosecond resolution, which could be electrical, optical, x- ray, gamma ray, or particle signals. The circuit comprises a superconductive monitor gate having at least two states which are distinguishable from one another. The monitor gate could be, for example, comprised of a Josephson device or a superconducting quantum interference device (SQUID). Switching means, including a source of the unknown signal, are provided to switch the state of the monitor gate. This switching means includes a sampling pulse source and a bias current source which are combined with the unknown signal to change the state of the monitor gate. A noise elimination means is also provided including a lock-in amplifier, a comparator, and a feedback loop. A time averaging technique eliminates any incorrect indications resulting from noise. A timing means establishes a timing reference and sampling delay, and includes the sampling pulse source, delay lines, and a trigger pulse source connected to the source of the unknown signal and to the sampling pulse source. A display, such as an x-y recorder or oscilloscope, indicates the unknown signal. The circuit has applications in all devices where fast unknown waveform must be measured exactly, and in the field of non-equilibrium superconductivity, where exceptionally high resolution and sensitivity are required.