Improved electronic measurement of the Boltzmann constant by Johnson noise Thermometry

TL;DR

This paper presents an improved electronic Johnson noise thermometry method to measure the Boltzmann constant with high precision, providing an alternative to acoustic gas-thermometry and contributing to the redefinition of the kelvin.

Contribution

It introduces a highly accurate electronic measurement technique for the Boltzmann constant using Johnson noise thermometry, achieving a low uncertainty and offering a different physical principle from traditional methods.

Findings

Measured Boltzmann constant as 1.3806514(48) x 10^-23 J/K

Achieved a relative standard uncertainty of 3.5 x 10^-6

Demonstrated consistency with CODATA values

Abstract

The unit of thermodynamic temperature, the kelvin, will be redefined in 2018 by fixing the value of the Boltzmann constant, k. The present CODATA recommended value of k is determined predominantly by acoustic gas-thermometry results. To provide a value of k based on different physical principles, purely electronic measurements of k were performed by using a Johnson noise thermometer to compare the thermal noise power of a 200 Ohm sensing resistor immersed in a triple-point-of-water cell to the noise power of a quantum-accurate pseudo-random noise waveform of nominally equal noise power. Measurements integrated over a bandwidth of 550 kHz and a total integration time of 33 days gave a measured value of k = 1.3806514(48)x10^-23 J/K, for which the relative standard uncertainty is 3.5x10^-6 and the relative offset from the CODATA 2010 value is +1.9x10^-6.