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TitleJohnson noise thermometry measurements using a quantized voltage noise source for calibration
Publication TypeJournal Article
Year of Publication2003
AuthorsNam, S.W., Benz S.P., Dresselhaus P.D., Tew W.L., White D.R., and Martinis J.M.
JournalIEEE Transactions on Instrumentation and Measurement
Pagination550 - 554
Date Published2003
ISSN00189456 (ISSN)
KeywordsCalibration, Digital to analog conversion, Electric frequency control, Electric potential, Johnson noise thermometry, Josephson array, Josephson junction devices, Microwave devices, Signal noise measurement, Temperature measurement
AbstractWe describe a new approach to Johnson noise thermometry (JNT) that exploits recent advances in Josephson voltage standards and digital signal processing techniques. Currently, high-precision thermometry using Johnson noise is limited by the nonideal performance of electronic measurement systems. By using the perfectly quantized voltage pulses from a series array of Josephson junctions, any arbitrary broadband waveform can be synthesized and used as a calculable noise source for calibrating the cross-correlation electronics used in JNT systems. With our prototype JNT system, we have found agreement to two parts in 10 3 with a 1σ uncertainty of 1 × 10 -3 between the voltage noise of a 100-Ω resistor in a triple-point Ga cell (T 90 = 302.916 K) and a pseudo-noise waveform with the same average power that is synthesized by a quantized voltage noise source. We estimate the temperature of the resistor to be 302.5 K ± 0.3 K (1σ uncertainty based on the uncertainty from the cross-correlation). With better characterization of our JNT system, we expect to achieve relative accuracies of parts in 10 5 for arbitrary temperatures in the range between 270 and 1000 K.

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