Dr. Holloway of NIST

One of the keys to developing new science and technologies is to have sound metrology tools and techniques. Fundamental to all electromagnetic measurements is having accurately calibrated probes, antennas, and power meters in order to measure either electric (E) fields or power. A stated goal of international metrology organizations, including the National Institute of Standards and Technology (NIST), is to make all measurements directly traceable to the International System of Units (SI). The world of measurement science is changing rapidly with the SI redefinition that occurred in November of 2018. As a result of the shift towards fundamental physical constants, the role of primary standards must change. NIST is investigating two fundamentally new direct SI traceable approaches: atom-based and mass-based (i.e., Planck’s constant and the kilogram), both of which will be traceable to Planck’s constant in the redefined SI. Traceability through Planck’s constant will exploit the quantum states of Rydberg (excited) atoms and traceability to the kilogram will make use of RF radiation pressure measurements.
The new atom-based new approach utilizes Rydberg atoms and will lead to a self-calibrated, SI traceable, E-field measurement, and has the capability to perform measurements on a fine spatial resolution in both the far- and near-fields. The atom-based approach is very broadband allowing for measurement from 10 MHz to 1 THz with one probe head. This approach can measure field levels from 1 micro-V/m (and possibly lower) to 100’s kV/m (and possibly higher). The atom-based approach has led to a fundamental new method for traceable RF power measurements. This new power measurement method can lead to the development of an in-situ calibrated sources as well. Finally, the atom-based approach has also led to many other applications: atom-based receivers/antennas, atom-based recording device of musical instruments, RF cameras, and many more applications.
The mass-base (through radiation-pressure) approach will allow power to be traceable of the kilogram and will allow for in situ measurements. This radiation-pressure technique could potentially allow electromagnetic power measurements and calibrations from 1mW to 1MW (and higher) regardless of frequency (from UV to RF) with one traceability chain. Significant progress has recently been made in the development of these novel approaches over the past few years and in this talk I will summary the work to date.

Biography:

Christopher L. Holloway (S'86-M'92-SM'04-F’10) is a Fellow of the IEEE and received the B.S. degree from the University of Tennessee at Chattanooga, and the M.S. and Ph.D. degrees from the University of Colorado at Boulder, both in electrical engineering. During 1992 he was a Research Scientist with Electro Magnetic Applications, Inc., in Lakewood, Co. His responsibilities included theoretical analysis and finite-difference time-domain modeling of various electromagnetic problems. From the fall of 1992 to 1994 he was with the National Center for Atmospheric Research (NCAR) in Boulder, Co. While at NCAR his duties included wave propagation modeling, signal processing studies, and radar systems design. From 1994 to 2000 he was with the Institute for Telecommunication Sciences (ITS) at the U.S. Department of Commerce in Boulder, Co., where he was involved in wave propagation studies. Since 2000 he has been with the National Institute of Standards and Technology (NIST), Boulder, CO, where he works on electromagnetic theory, quantum optics, and atom-based metrology. He is also on the Graduate Faculty at the University of Colorado at Boulder.
He holds U.S. Patents on electromagnetic absorbing materials, radar systems and antennas for atmospheric radars, on volume measurements devices, and on various atom-based devices for both field and power measurements. He has an h-index of 48 with over 280 technical articles including: 132 refereed journal articles, 123 conference papers, 102 conference presentations without publications, 4 book chapters, and 31 technical reports. These publications cover a large array of topics including, theoretical and applied electromagnetics, remote sensing, measurement techniques, materials, atom-based metrology, and recording guitars with atoms.

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