Development Of A Quantum Voltage Calibrated Johnson Noise Thermometer

Temperature is one of the seven fundamental physical quantities in theInternational System of Units. Accurate measurement of the thermodynamictemperature measured is the basic of the definition of the international temperaturescale. Johnson noise thermometry infers the thermodynamic temperature by mesuringthe fluctuating voltage generated from the Brown motion of electrons in a resistor. Inthis paper, a quantum voltage calibrated Johnson noise thermometer isdeveloped to measure the thermodynamic temperature accurately. We describe themain points of the system and temperature measurement in detail as follows:1. Single tone sine wave with amplitude of1μV and frequency of100kHz, andcomb-like quantum voltage pseudo noise are synthesized by the quantum voltagearbitrary waveform synthesis technique.2. The software of data acquisition and data processing is completed withLabVIEW.3. The nonlinearity of the preamplifier in the system is measured with two-tonewaveforms synthesized by the quantum voltage pseudo noise source.4. The thermodynamic temperature of triple point of water was measured withthe accomplished system. The measurement achieved a relative offset of0.510^-6from the value of ITS-90and a relative statistical uncertainty of23μK/K forintegration period of10hours.