Picosecond switching measurements of a Josephson tunnel junction

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1987

OSTI ID:7199920

Dykaar, D R

These experiments make use of both pico- and subpicosecond lasers in conjunction with photoconductive switches to create current pulses with fast rise time, adjustable amplitude, and in some cases, adjustable width. Pulses which are then used as excitations for Josephson tunnel junctions. To measure the time-domain response of these devices directly, a cryogenic electro-optic sampler was implemented with an unprecedented time resolution. An electrical transient propagated on a transmission line, with a rise time of 360 fs - a record - was measured. A new detection scheme was implemented that allowed measurements approaching the shot-noise limit. For the first time, measurements were made on a single junction which cannot be explained using a simple quasi-static model, i.e., a summation of bias and applied pulse current did not yield the critical value. In addition, these results were successfully modeled using the RCSJ model. Finally, chaos was observed in the I-V characteristics of these devices due to the periodic kicks that these current pulses represent. This is the first observation of chaos in a periodically kicked junction. Results led to the author to develop the concept of a critical pulse charge, rather than a critical current, as the measure of the junction switching threshold.

• Research Organization: Rochester Univ., NY (USA)
• OSTI ID: 7199920
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
420201* -- Engineering-- Cryogenic Equipment & Devices
420800 -- Engineering-- Electronic Circuits & Devices-- (-1989)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTRONIC CIRCUITS
JOSEPHSON JUNCTIONS
JUNCTIONS
LASERS
MEASURING METHODS
PULSE CIRCUITS
Q-SWITCHING
RESOLUTION
SUPERCONDUCTING JUNCTIONS
TIME RESOLUTION
TIMING PROPERTIES