Noise and chaos in driven Josephson junctions. Technical report

Technical Report · Sun Mar 01 04:00:00 EST 1987

OSTI ID:6842527

Hu, Q

We have studied in detail the response of several Nb-a-si-Nb junctions to laser radiation at far-infrared frequencies, 245, 419, and 604 GHz. All these Nb-a-Si-Nb junctions were made by the SNAP (Selective Niobium Anodization Process) procedure on a single wafer. They all have the plasma frequency fp = (2eIc/hC) 2 pi about 400 GHz. When we irradiate the junctions at 419 GHz, the radiation frequency is very close to the plasma resonance frequency. We saw very rich nonlinear dynamic effects exhibited in the dc I-V characteristics, such as, negative resistance regions, subharmonic steps, and noisy I-V curves which cannot be explained by thermal or other noise sources. By using a RCSJ (Resistively and Capacitively Shunted Junction) model, modified to include a piecewise nonlinear resistance, with an appropriate amount of noise, we can reproduce the dc I-V curves of the irradiated junctions very accurately in both digital and analog simulations. The agreement between the simulations and the experimental results is excellent in those qualitative features on dc I-V curves such as the appearance of certain subharmonic steps and negative resistance regions. The agreement is very good in some of the quantitative comparisons such as the step width dependence on the laser power.

• Research Organization: Harvard Univ., Cambridge, MA (USA). Div. of Applied Sciences
• OSTI ID: 6842527
• Report Number(s): AD-A-194765/4/XAB; TR-25
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ANALOG SYSTEMS
DIGITAL SYSTEMS
DOCUMENT TYPES
ELECTROMAGNETIC RADIATION
ELEMENTS
FAR INFRARED RADIATION
INFRARED RADIATION
IRRADIATION
JOSEPHSON JUNCTIONS
JUNCTIONS
LASER RADIATION
METALS
NIOBIUM
NOISE
PROGRESS REPORT
RADIATIONS
SUPERCONDUCTING JUNCTIONS
TRANSITION ELEMENTS