NIST researchers have developed a new “noise thermometry” system that measures temperature using the random motion of electrons, potentially leading to a redefinition of the Kelvin temperature scale. The system, which is five times more precise than previous noise thermometry methods, could help update the 54-year-old definition of the Kelvin unit by determining Boltzmann’s constant with greater accuracy.
The NIST Johnson noise thermometry (JNT) system uses a unique quantum voltage source to measure electrical noise in resistors, which is directly proportional to temperature. This electrical approach to temperature measurement is simpler and more compact than traditional methods, and could be used as a primary measurement standard in national metrology labs.
The system’s most significant application may be in determining Boltzmann’s constant, a key value used in scientific calculations to relate energy to temperature in particles. The international metrology community is expected to fix the value of this constant in the coming years, which would then be used to redefine the Kelvin as part of an effort to link all units to fundamental constants.
While the current Kelvin is defined using the triple-point temperature of water, the JNT system could provide a more stable and reproducible approach to temperature measurement by relying on electrical noise rather than physical objects or substances. However, the system’s slow speed (about one month to achieve the necessary precision) may limit its immediate applications.
Keywords: Quantum, Measurement, Temperature, Kelvin, Boltzmann
