The electronic fluctuations in voltage and current that exist in a normal conductor are a fundamental measure of thermodynamic temperature. Many challenging metrology and electronic design problems must be solved in order to fully exploit Johnson noise as a primary thermometer with high accuracy. Opportunities exist for experimental investigations in Johnson Noise Thermometry (JNT) with advanced quantum-based voltage synthesis techniques. JNT can be implemented as both an absolute method and a temperature scaling technique relative to the current international temperature scale ITS 90. The established uncertainty benchmark for absolute JNT is 12 ppm at the triple point of water (273.15 K), with more recent measurements achieving statistical uncertainties of 3 ppm. For temperatures in the range 505 K to 933 K, the current benchmarks for relative JNT are 26 ppm to 35 ppm. Results in this temperature range are already directly impacting our knowledge of the platinum reference function that is the basis for all international temperature dissemination between 13.8 K and 1234 K

The NIST JNT research efforts are a collaboration between the Quantum Electromagnetics Division in Boulder, CO and the Sensor Science Division in Gaithersburg, MD. In Boulder, opportunities in JNT system research include ultra-low noise system design, SFQ electronics, electromagnetic interference (EMI) rejection/correction methods, and digital signal processing and network modeling. Other research topics are High-Tc superconductive Josephson junction array waveform synthesizers and compact cryogenic design for the development of practical primary standards. Research that emphasizes and augments state-of-the-art techniques in these areas is most needed. Further JNT research opportunities are available in Gaithersburg, MD and are described under a separate posting listed for NRC advisor Tew, Weston L.

 

key words

Digital signal processing; Electronic design; Johnson noise; Network analysis; Cryogenic design; Noise correlation; Noise thermometry; Single flux quantum devices; Waveform synthesis;

Citizenship:  Open to U.S. citizens

Level:  Open to Postdoctoral applicants