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The Physical Measurement Laboratory’s Responses to the Recommendations of the 2018 Assessment Report
Five years ago, in 2018, this report’s predecessor report, An Assessment of Four Divisions of the Physical Measurement Laboratory at the National Institute of Standards and Technology: Fiscal Year 2018 (NASEM 2018; hereafter “FY 2018 Assessment”) offered four key recommendations to the National Institute of Standards and Technology (NIST) regarding the operation of the Physical Measurement Laboratory (PML) and, in particular, the four PML divisions that have been reviewed again in this report: the Applied Physics Division, the Quantum Physics Division, the Quantum Electromagnetics Division, and the Time and Frequency Division. Two of the recommendations were aimed generally at all four of the PML divisions in the review, while the other two were intended for specific divisions. The 2018 report also offered some observations about what might act to improve specific divisions that did not rise to the level of recommendations.
In preparation for visits from the committee working on this current report, NIST staff provided descriptions of how NIST and PML had responded to the recommendations in the 2018 report. The responses are reproduced below (unedited, without citations)—organized into responses to the two general recommendations and then responses to recommendations and observations relating to each of the four divisions.
GENERAL RECOMMENDATIONS
Repair and Revitalization of NIST Facilities. The FY 2024 budget request includes an increase of $48.6 million to support infrastructure improvements and enhancement of research spaces, ensuring that NIST can support a leading-edge research and development program that advances U.S. innovation in quantum information science, biotechnology, artificial intelligence, advanced manufacturing, cybersecurity, privacy, 5G and 6G telecommunications, and other critical programs.
Gaithersburg Central Utility Plant (CUP) Modernization. The FY 2024 budget request includes an increase of $50.0 million to provide for the full modernization of the CUP to replace all existing infrastructure and older equipment with new state-of-the-art sustainable systems.
Multiple Heating, Ventilation, and Air Conditioning] System Replacements. The FY 2024 budget request includes an increase of $30.0 million to ensure air handling units and related heating, ventilation, and air conditioning distribution systems in most buildings across the Gaithersburg, Maryland, campus provide clean, temperature-controlled air at proper ventilation rates.
FY 2018 Assessment:
Recommendation 2: The Physical Measurement Laboratory (PML) should maintain awareness of changes in patent and intellectual property procedures to encourage and more efficiently enable the movement of PML discoveries into commercial space.
NIST response:
All NIST staff, including PML staff, are required to disclose their inventions to management and to our Technology Partnership Office (TPO). TPO assesses the invention for commercial potential and—for PML inventions—recommends to the PML Director, Jim Kushmerick, whether a patent should be sought. PML management works closely with TPO to reach equitable decisions on patenting promising inventions.
APPLIED PHYSICS DIVISION
FY 2018 Assessment:
Recommendation 3: Physical Measurement Laboratory (PML) should study the costs and benefits of acquiring a clinical-class magnetic resonance imaging machine that would assist in phantom design and enable testing onsite.
NIST response:
At this stage, the procurement and maintenance costs of a regular clinical magnetic resonance imager was deemed inappropriate given NIST’s limited capabilities to perform extensive animal and/or human research, which would leave such a machine under-utilized. Instead NIST has established close collaborations with CU Boulder and Anschutz Medical Campuses, both of which provide NIST with more cost-effective access to clinical systems. We also maintain collaborations with researchers at the NIH, where we perform animal-based research on both clinical MRI scanners as well as higher field systems, and with MGH/Harvard Medical School where human studies are performed on a home-built low-field scanner. Additionally, NIST has procured a less expensive low-field Hyperfine clinical system with which we are able to conduct limited in-house phantom and human studies.
QUANTUM ELECTROMAGNETICS DIVISION
FY 2018 Assessment:
The QED would benefit from increased guidance on the value to NIST of patent activity vis-à-vis journal publications and other metrics. (See Recommendation 2 above.) The environmental controls in
the laboratory space need to be improved. The aging facilities have problems with the building envelope, such as the observed roof leaks. (See Recommendation 1 above.)
NIST response:
See responses to Recommendations 1 and 2.
TIME AND FREQUENCY DIVISION
FY 2018 Assessment:
The problem of transmitting time signals and comparing frequency standards in this new regime of precision poses a serious scientific and technical challenge for the TFD. Comparisons in the same laboratory are relatively straightforward, but the problem of comparisons at large distances remains to be solved.
Recommendation 4: Physical Measurement Laboratory (PML) should continue its work to develop methods for distributing time over long distances at the newly attainable levels of precision.
NIST response:
The TFD is pursuing two main methods to compare frequency standards at the precision offered by optical clocks: through two-way frequency-comb based comparisons (over free space and optical fibers) and through the development of a transportable ytterbium optical lattice clock.
For the comb-based optical time transfer measurements, TFD has collaborated with JILA and the Fiber Sources and Applications Group in NIST’s Communications Technology Laboratory to perform the most accurate frequency ratio measurements made to date (Nature, 2021). These measurements used fiber-optic based frequency transfer. The teams also performed an optical clock comparison through turbulent air (Physical Review Research, 2020), showing that they can perform comparisons below the 10–18 level.
The NIST portable Yb lattice clock has been under development since 2018 and became operational in 2022. Deployment of the portable Yb clock at the US Naval Observatory (USNO) in Washington DC in March of 2023 was the system’s first remote frequency comparison. The portable Yb clock was measured against a USNO Rb atomic fountain (one of their most stable systems) over several days, with a focus on characterization of the frequency stability and phase noise between the two systems. The measurements are consistent a frequency stability of 1 × 10-15 at 10,000 seconds, limited by the Rb fountain. This work will be presented at the [joint conference of the European Frequency and Time Forum & the IEEE International Frequency Control Symposium] in May. After the uncertainty budget is evaluated and published, planned future experiments include using the portable system with optical time transfer over free space to measure the gravitational redshift between Boulder and the summits of Flagstaff Mountain and Mount Evans. The system will also be used to validate the performance of frequency standards that are being developed at other institutes through the [Defense Advanced Research Projects Agency] A-Phi and ROCk’N programs.
Finally, the portable clock will eventually be deployed internationally for optical clock frequency ratio measurements at other NMIs.
QUANTUM PHYSICS DIVISION
FY 2018 Assessment:
QPD/JILA has strong overlapping interests with other PML divisions, such as the TFD. Because QPD/JILA is housed in a CU facility and not at NIST Boulder, there is little trickle down to QPD/JILA of technical improvements in TFD.
NIST response:
The short distance (2 miles) between JILA and the NIST campus has an impact on scientific interactions, with JILA’s position on the CU campus enabling a different set of interactions for its researchers. However, since the previous review, the large BACON Collaboration has operated a network of three optical atomic clocks in Boulder, consisting of a TFD aluminum-ion clock (Hume), a TFD ytterbium lattice clock (Ludlow), and a QPD strontium lattice clock (Ye), and a TFD optical network (Fortier). In addition, there are now highly productive QIS collaborations between the TFD ion storage group (Bollinger and Slichter) and the QPD Rey and QPD Kaufman groups, and between the TFD Atomic Devices and Instrumentation Group (Kitching) and the QPD Thompson group. The QPD is also collaborating on numerous projects with other NIST divisions. Finally, these efforts are all two-way collaborations between groups with different expertise and styles, but of similar overall quality, that bring added value to all researchers.
REFERENCE
NASEM (National Academies of Sciences, Engineering, and Medicine). 2018. An Assessment of Four Divisions of the Physical Measurement Laboratory at the National Institute of Standards and Technology: Fiscal Year 2018. Washington, DC: The National Academies Press. https://doi.org/10.17226/25281.