Effects of noise on the dc and far-infrared Josephson effect in small-area superconducting tunnel junctions
- 1 September 1984
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 30 (5), 2503-2516
- https://doi.org/10.1103/physrevb.30.2503
Abstract
We report investigations of the effect of noise on the Josephson effect in small-area tunnel junctions, both at dc and when the junction is irradiated by 604-GHz laser radiation. The junctions were made of Sn-SnO-Pb layers of ~1 area, fabricated on crystal quartz substrates with integral planar resonant dipole antennas. The observed systematic falloff of the product with increasing resistance can be accounted for by the thermal activation model (transition-state theory) if an effective noise temperature (presumably extrinsic) of 8±1 K is assumed. The noise rounding of the high-voltage steps can be fitted with the analytic results obtained by P. A. Lee [J. Appl. Phys. 42,325 (1971)] for an overdamped junction, but using a fictitious elevated noise temperature of ~eV/ (~20-30 K for typical steps at ~5 mV) to incorporate the nonthermal shot noise as an effective increase in noise temperature. We have also developed a computer simulation which builds in the effects of the nonlinear quasiparticle resistance of the junctions as well as the voltage-dependent shot noise; it can account for the entire curve, including the photon-assisted tunneling steps. Noise currents are found to have much less effect on the finite-voltage Josephson steps than in reducing the product, which explains the anomalously high ratios of step widths to measured that are found experimentally.
Keywords
This publication has 37 references indexed in Scilit:
- Conductance fluctuations and low frequency noise in Josephson junctionsIEEE Transactions on Magnetics, 1983
- Photon-assisted tunneling and AC Josephson effect at 246 and 604 GHz in small-area superconducting tunnel junctionsIEEE Transactions on Magnetics, 1983
- Quantum Fluctuations in the Tunneling between SuperconductorsPhysical Review Letters, 1982
- High-frequency losses in tin Josephson tunnel junctionsPhysical Review B, 1978
- Stencil technique for the preparation of thin-film Josephson devicesJournal of Vacuum Science and Technology, 1978
- Design of Printed Resonant Antennas for Monolithic-Diode DetectorsIEEE Transactions on Microwave Theory and Techniques, 1977
- Thermal fluctuations and the Josephson supercurrentPhysica, 1971
- Effect of Noise on the Current-Voltage Characteristics of a Josephson JunctionJournal of Applied Physics, 1971
- Multiphoton Process Observed in the Interaction of Microwave Fields with the Tunneling between Superconductor FilmsPhysical Review B, 1963
- Brownian motion in a field of force and the diffusion model of chemical reactionsPhysica, 1940