We report on our progress in measuring the Boltzmann’s constant by Johnson noise thermometry (JNT) using an integrated quantum voltage noise source (IQVNS) that is fully implemented with superconducting integrated circuit technology. The IQVNS generates calculable pseudo white noise voltages to calibrate the JNT system. Thermal noise of a resistor placed at the temperature of the triple point of water was measured precisely by the IQVNS-based JNT. We accumulated more than 2000 data points to determine the Boltzmann’s constant. The experimentally obtained Boltzmann’s constant was    $k_{\mathrm {exp}} = 1.3806493 \times 10^{-23}$    J/K with a relative statistical uncertainty of    $8.6 \times 10^{-6}$   , which agreed well with the 2014 Committee on Data for Science and Technology value with a relative offset of    $+ 0.6\times 10^{-6}$   .
['Chiharu Urano', 'Takahiro Yamada', 'Masaaki Maezawa', 'Kazuaki Yamazawa', 'Nobu-hisa Kaneko']
Measuring the Boltzmann’s Constant Using Superconducting Integrated Circuit