Traceable Coulomb Blockade Thermometry

TL;DR

This paper introduces a precise method for measuring cryogenic temperatures using Coulomb blockade thermometry, achieving sub-0.5% uncertainty with improved electrical measurement techniques and robust data analysis methods.

Contribution

It demonstrates two analysis techniques for Coulomb blockade thermometry and provides a comprehensive uncertainty analysis, enhancing traceable temperature measurements at cryogenic levels.

Findings

Uncertainty below 0.5% in 20 mK to 200 mK range

Both analysis methods yield consistent temperature estimates

Deviation from reference temperatures is less than 0.67%

Abstract

We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods are demonstrated: numerical fitting of the full conductance curve and measuring the height of the conductance dip. The complete uncertainty analysis shows that using either analysis method the relative combined standard uncertainty (k = 1) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 0.5 %. In this temperature range, both analysis methods produced temperature estimates that deviated from 0.39 % to 0.67 % from the reference temperatures provided by a superconducting reference point device calibrated against the Provisional Low Temperature Scale of 2000.