Effect of additive noise and bandpass filter on the performance of a Josephson junction noise thermometer

Journal Article · Wed Sep 01 04:00:00 EDT 1982 · Rev. Sci. Instrum.; (United States)

DOI:https://doi.org/10.1063/1.1137183· OSTI ID:5034593

Soulen, Jr, R J; Vechten, D V; Seppae, H

A Josephson junction may be used to convert the voltage fluctuations generated by Johnson (i.e., thermal) noise in a resistor into frequency fluctuations. The variance of the frequency fluctuations is thus a measurement of the Johnson noise and, therefore, of the temperature. This particular type of noise thermometer has been used at the National Bureau of Standards as part of a program to define a cryogenic temperature scale. We have studied the detailed influence of two types of post-detection bandpass filters (square and one-pole Butterworth) on the measured variance. We report here on these measurements and the circuit model used to fit them. The conclusion is that small but well understood corrections must be applied to the measured variance whenever the measurement time (i.e., gate time) of the frequency becomes comparable with the response time (defined as the inverse of the bandwidth) of the bandpass filter.

• Research Organization: Center for Absolute Physical Quantities, National Bureau of Standards, Washington, D.C. 20234
• OSTI ID: 5034593
• Journal Information: Rev. Sci. Instrum.; (United States), Journal Name: Rev. Sci. Instrum.; (United States) Vol. 53:9; ISSN RSINA
• Country of Publication: United States
• Language: English

Related Subjects

420201* -- Engineering-- Cryogenic Equipment & Devices
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DATA
ELECTRIC POTENTIAL
ELECTRONIC CIRCUITS
EQUIVALENT CIRCUITS
EXPERIMENTAL DATA
FILTERS
FLUCTUATIONS
FUNCTIONS
IN CORE INSTRUMENTS
INFORMATION
JOSEPHSON JUNCTIONS
JUNCTIONS
MEASURING INSTRUMENTS
NOISE THERMOMETERS
NUMERICAL DATA
PERFORMANCE
REACTOR INSTRUMENTATION
RESPONSE FUNCTIONS
SUPERCONDUCTING JUNCTIONS
TEMPERATURE MEASUREMENT
THERMOMETERS
VARIATIONS