Quantized fluctuations in the Josephson oscillations of a shunted superconducting point contact
作者:
R. D. Sandell,
J. P. Wikswo,
J. M. Pickler,
B. S. Deaver,
期刊:
Journal of Applied Physics
(AIP Available online 1973)
卷期:
Volume 44,
issue 7
页码: 3312-3318
ISSN:0021-8979
年代: 1973
DOI:10.1063/1.1662753
出版商: AIP
数据来源: AIP
摘要:
By detecting the oscillation of a tuned circuit resonant at frequencyv0coupled to a shunted superconducting point contact we have observed oscillations not only at the Josephson voltageV=&phgr;0v0, where &phgr;0is the flux quantum, but also at voltagesVn=gn(T)&phgr;0v0, wheregn(T)is a continuous monotonic function of temperature. For most temperaturesgn(T)=N(T)/n, whereNandnare integers, however there are ranges of temperature over whichg1(T) varies rapidly through nonintegral values and the voltagesVnare not harmonically related. The level of oscillation of the tuned circuit was used to measure the power spectrum of the voltage waveform at the point contact and the linewidths were found to be oscillatory functions of temperature with minima whenV1=N&phgr;0v0and maxima whenV1=(N+1/2)&phgr;0v0. The Josephson oscillation of the shunted point contact consists of pulses ofNflux quanta (N&phgr;0) crossing the point contact at a repetition frequencyv0. The temperature dependencies are interpreted in terms of fluctuations inN. The relationship between these results and some temperature dependent features observed on theI‐Vcurves of point contacts and some implications for noise thermometry are discussed.
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