Sadeg M. Faris

Generation and measurement of ultrashort current pulses with Josephson devices

Experimental demonstration of an ultrashort‐pulse generator and a novel sampling technique to measure its pulse shape is reported. The pulse generator, which uses Josephson interferometers, is designed to be dc powered and self‐resetting. Its pulses are measured to be 26 ps in duration at a simulated maximum frequency of 2.5 GHz. The sampling technique is useful for measuring general fast waveforms with unprecented sensitivity and resolution extendable to subpicosecond time scale.

Loop decoder for Josephson memory arrays

A detailed theoretical and experimental investigation is presented concerning a novel so-called loop decoder using Josephson interferometers as the active elements. Successful operation of a DC powered, full 3-bit decoder is demonstrated with large operating margins. Addressing time is measured to be 180 ps and decoding time per stage is measured to be 30 ps. Excellent agreement is obtained between the experiments and computer simulations, thus establishing that present Josephson circuit models are reasonably accurate and well understood.