Primary current-sensing noise thermometry in the millikelvin regime

Area of Science:

• Low-temperature physics
• Thermodynamics
• Metrology

Background:

• Low-temperature platforms below 1 K are critical for fundamental science and emerging technologies.
• Accurate thermodynamic temperature measurement is essential for the reliable operation of these platforms.
• Disseminating the kelvin unit at these low temperatures requires precise thermometry.

Purpose of the Study:

• To introduce a practical and user-friendly primary current-sensing noise thermometer (CSNT).
• To enable reliable and traceable thermometry in the sub-kelvin regime.
• To support the dissemination of the kelvin unit at ultra-low temperatures.

Main Methods:

• Design and optimization of a CSNT for the sub-kelvin temperature range.
• Addressing noise sources and thermalization for accurate measurements.
• Establishing the primary nature of the thermometer and quantifying uncertainty contributions.

Main Results:

• A relative uncertainty of 1.53% was achieved using standard laboratory instrumentation.
• Initial comparisons showed good agreement between the primary CSNT and a superconducting reference device (PLTS-2000).
• Measurements were conducted between 66 mK and 208 mK.

Conclusions:

• The developed CSNT provides a practical solution for primary thermometry below 1 K.
• The thermometer is suitable for reliable and traceable measurements in this critical temperature range.
• The results support the accurate dissemination of thermodynamic temperature at ultra-low temperatures.