The recent advances in ac waveform synthesis using quantized voltage pulses have enabled new methods for the measurement of absolute temperature. At the same time, the increased linearity and sampling rates of digital electronics have established frequency-domain processing as the preferred technique in Johnson noise thermometry (JNT). The spectral-ratio quantum-based JNT developed at NIST has achieved measurement uncertainties as low as 12 μK/K at 273 K and 40 μK/K for temperatures in the range 500 K to 700 K, with even lower uncertainties achievable in the near term. We describe the theory and experimental realization of the quantized voltage noise source (QVNS) and spectral JNT from the metrology standpoint as intrinsic temperature standards. The role of JNT in special point-of-use thermometry applications and future research directions are also discussed.
Proceedings Title: Measurement Science Conference 2011
Conference Dates: March 16-18, 2011
Conference Location: Pasadena, CA
Conference Title: Measurement Science Conference
Pub Type: Conferences
noise thermometry, Johnson noise, ac Josephson standard, intrinsic standards