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Quantum Physics Division

The Quantum Physics Division is the National Institute of Standards and Technology (NIST) component of JILA—the latter established in 1962 and located on the campus of the University of Colorado Boulder (CU). These two conjoined organizations together constitute a very unusual but extremely successful collaboration. In fiscal year 2022, the Quantum Physics Division funding was approximately $24.4 million, with about half of that funding from NIST and half from external sources. Important aspects of JILA funding include the JILA Physics Frontier Center, which has been continuously funded by the National Science Foundation (NSF) since 2006, as well as the q-SEnSE Institute (Quantum Systems through Entangled Science and Engineering), an NSF Quantum Leap Challenge Institute partnership of 12 research organizations launched in 2020 and directed by NIST and JILA Fellow Jun Ye.

JILA employs nine NIST-supported fellows, including the current JILA chair, out of a total of 29 JILA fellows. The JILA fellows act effectively as a faculty department at NIST and CU, collectively making decisions regarding research activities and faculty hiring to maintain the highly collaborative environment that has helped make it successful to date. The fellows try to guide JILA toward new frontiers in precision measurement and quantum, molecular, and biological physics, among other areas.

ASSESSMENT OF TECHNICAL PROGRAMS

JILA is clearly one of the crown jewels of NIST. It is a special place, absolutely world class, and needs to continue being a special place in the future. As one JILA fellow stated: “We are not here to come second.” Most, if not all, fellows are world-renowned scientists who work at the forefront of their respective research areas. The general technical program of JILA research is the development of fundamental measurement science, pioneering new technologies in the field of quantum physics and the training of early career researchers.

The central work of the Quantum Physics Division at JILA is in fundamental precision measurements in various areas of chemistry, physics, and biological physics. The measurements range from ultra-precise frequency measurements for time and frequency standards using quantum-enhanced techniques to fundamental measurements, such as of the electric dipole moment of the electron, and from the search for dark matter with high-Q resonators to precision measurements for biological and chemical processes.

The scientific expertise of the Quantum Physics Division ranges from quantum information science and exploring applications of quantum-enhanced sensing to quantum information processing and quantum simulations. In addition, there is expertise in the micro-fabrication of materials and electromechanical devices. Special knowledge and skills are available in atomic and molecular physics, especially on quantum many-body physics and controlling molecule formation and chemical reactions.

In the area of quantum information processing, the Quantum Physics Division has developed and demonstrated trapped alkaline-earth atoms in tweezer arrays, demonstrated record-breaking long coherence times, realized tweezer-programmable two-dimensional quantum walks, and demonstrated long-lived Bell states. There is theoretical expertise with quantum many-body physics (the group of Ana Maria Rey), which in collaboration with the Time and Frequency Division (Time and Frequency Division Group of John Bollinger) resulted in the demonstration of methods to harness and manipulate spin--

interactions mediated by phonons in Penning traps. The collaboration of the Ana Maria Rey and Jun Ye teams demonstrated Hamiltonian engineering of spin-orbit coupled fermions in an optical lattice clock and showed that such clocks provide superior quantum coherence with interactions that can be manipulated to realize quantum simulations of spin models.

Precision measurements are central to the joint work of many teams of the division. The close collaboration of the teams of Jun Ye (JILA), Andrew Ludlow (NIST), and David Hume (NIST) has resulted in groundbreaking achievements over the past 5 years. This resulted in frequency ratio measurements with an 18-digit accuracy using an optical clock network, the amazing resolution of the gravitational redshift across a millimeter-scale atomic sample, the demonstration of a tweezer-array-based atomic clock, and the setting of a new bound of the electron’s electric dipole moment. Precision measurements by Konrad Lehnert’s group with high-Q microwave resonators enabled the search for wave-like dark matter with detection at the quantum limit.

Atomic, molecular, and optical physics has always been at the heart of the Quantum Physics Division work at JILA, especially research concerned with cold atoms and molecules. The manipulation of atomic and molecular samples and the control of their interactions enable new studies of quantum many-body physics and the respective quantum control. Special highlights during the period of this assessment included the demonstration of methods to use long-range exchange interactions in an optical cavity to generate new phases of matter, which is useful for optical clocks; the demonstration of cavity quantum electrodynamics measurements of the strontium milli-Hertz clock transition; theoretical work on the dynamical generation of spin-squeezing in ultra-cold molecules; and the demonstration of Pauli-blocking in atom light scattering.

Nanoscience expertise in the Quantum Physics Division intersects quantum optics, superconducting quantum circuits, and nanomechanical devices in close collaboration with the scientists at NIST Boulder. Research highlights during the past 5 years include the conversion of photons from the microwave to the optical regime with the demonstration of superconducting qubit readout with an electro-optomechanical transducer, among others.

There are three groups doing biological physics in the Quantum Physics Division: those run by Tom Perkins, Ralph Jimenez, and David Nesbitt. Nesbitt has recently begun a collaboration with Jun Ye to do ultra-sensitive detection of biomarker aerosols using femto-second frequency combs.

Tom Perkins has systematically been developing single-molecule force-extension curves using atomic force microscopy (AFM). Perkins uses commercial AFMs (Asylum) but specializes in the improvement of the AFM’s crucial cantilevers. The fundamental problem this project has addressed is optimizing the cantilevers for stable, accurate, and highly sensitive force measurements, while simultaneously decreasing the mechanical relaxation time from the standard 400 µsec to 2 µsec, allowing for much improved measurements of biomolecule conformational dynamics. This technology took extensive advantage of scanning electron microscopes and focused ion beam technologies on the CU campus.

A particularly exciting development has been including the optical excitation of bacteriorhodopsin molecules at the same time that the AFM is measuring the conformational rigidity of the bacteriorhodopsin at the µsec time scale. Because the light-activated dynamics of bacteriorhodopsin are critical to its function of charge-pumping across a membrane, this opens a new avenue of exploring functional protein dynamics.

Ralph Jimenez has engineered intrinsically fluorescent proteins to have enhanced photophysical properties, such as brightness, by using a combination of random and targeted mutagenesis, and the project has designed several novel microfluidic systems for screening libraries of mutants. A recent effort was to use entangled down-converted photons for two-photon excitation microscopy. The hope was that an entangled pair of photons would have enhanced two-photon excitation owing to the spatial correlations of the entangled pair. This has proved to be a challenging task.

David Nesbitt works in both the areas of photochemical dynamics and time-resolved biomolecule folding. The three-dimensional momentum distributions of photo-electrons (excited by the multi-photon plasmon excitation of complex metallic nanostructures) are measured using a technology called scanning photoelectron imaging microscopy. These photoelectrons can potentially be used for photo-driven

chemistry of absorbed molecules on the nanostructures in a directed manner. This effort appears to be rather isolated and could benefit from a direct engagement with time- and space-resolved studies of surface electric fields and surface plasmon polaritons, using related forms of photo-electron emission microscopy in other institutions in both the United States and Europe.

The more direct biological physics work is on the time-resolved folding dynamics of RNA molecules. The basic technology uses fluorescent resonant energy transfer with picosecond visible laser sources to measure the structural dynamics of RNA molecules, with the use of a pulsed near-infrared laser to create a transient “bath-tub,” which allows for the determination of the free energies of folding.

A very exciting recent collaboration, driven by the COVID-19 pandemic, is a collaboration between David Nesbitt and Jun Ye to analyze biomarkers in aerosols using a femtosecond frequency comb injected into a high-finesse optical cavity. The frequency comb consists of 25,000 discrete channels covering a range of 3–10 microns, with an effective path length of 10 km, providing enormous sensitivity. Preliminary results using breath samples from 173 CU people yielded an 83 percent “area under curve” true-positive versus false-positive rate, which is comparable to state-of-the-art polymerase chain reaction tests. Potentially this technology could be used for a large spectrum of human diseases.

Challenges and Opportunities in Biological Physics

Historically, the biological physics section has had sub-critical mass, but given the extraordinary strengths of the other groups in the division, there is no real room for biological physics to grow. There is a potential retirement coming up. The good news is the new collaborations growing between biological physics and the atomic, molecular, and optical parts of the division, which the panel strongly encourages. There is a growing interest in quantum aspects of biology; this may be an area for further collaborations.

ASSESSMENT OF SCIENTIFIC EXPERTISE

The JILA Quantum Physics Division group leaders are world class scientists. They carry out research at the frontiers of their fields and in many ways define those frontiers. Their achievements are evidenced by an extraordinary number of awards that they have received at the international, national, and NIST levels (4 of the 40 NIST fellows are members of the division). Particularly worth mentioning in the assessment period are Ana Maria Rey’s 2023 election to the National Academy of Sciences, the award to Jun Ye of both the 2020 Micius and the 2022 Breakthrough prizes, and the recognition of Adam Kaufmann with the 2023 New Horizon Prize in Fundamental Physics.

Challenges and Opportunities

The emerging quantum information industry is aggressively recruiting freshly minted PhD physicists and engineers and offering them extremely attractive starting salaries and incentives. This situation is likely to be exacerbated if this industry continues its exponential growth. Because typical postdoctoral salaries are not competitive with such offers this can be expected to result in significant recruitment challenges. Although the top-notch research being performed at JILA will certainly remain a significant attraction, it is important not to underestimate this issue and to be proactive in addressing it. The future will be grim if JILA and NIST lose all our best young people to industry at such an early stage.

Some of the graduate students reported a laboratory and group culture or environment in which psychological safety is an issue. Indeed, they reported not feeling safe asking scientific or research questions that they think might be too basic or might make them feel less smart. This concerns the panel deeply and is clearly a problem that needs to be addressed between PML and CU.

BUDGET, FACILITIES, EQUIPMENT, AND HUMAN RESOURCES

Budget

The funding required to carry out the division’s current tasks is provided in almost equal parts by NIST appropriations ($12.6 million, 52 percent) and third-party non-NIST funding ($11.8 million, 48 percent). Of the non-NIST finding, 88 percent is from government sources: NSF ($3.03 million), the Department of Defense ($4.25 million), the Department of Energy ($2.84 million), and the National Aeronautics and Space Administration ($105,000), and 6 percent each is from academic and industry sources. Thanks to the division’s remarkable strength in attracting external support evidenced by these numbers, its total operational funding appears to be currently adequate.

However, the continuing excellence of JILA is seriously endangered by a combination of aging and lacking facilities and infrastructure. These problems are a critical issue, and there is an urgent need to improve and expand the laboratory facilities. The Quantum Physics Division leadership indicated that an additional $200 million in capital funds for facility upgrades—both new construction and renovation—would barely bring the facilities up to the standards of international peer institution.

Technical Support

Shop technicians are the secret weapon of JILA. Their technical support is highly appreciated by students and scholars alike. However, the panel heard during its visit that there are constant challenges to keep funding the technical support staff and facilities at a level that makes their use viable for the principal investigators (PIs)—if the base funding provided for the shops is not sufficient, then the user fees are too high to be affordable. This decision is one of choosing between funding additional research activities or maintaining the support capability given all available funding. Right now, JILA is at the threshold of a challenge in the matter of maintaining shops.

Laboratory Space and Conditions

Aside from the budgetary challenges to maintain the technical infrastructure, the panel has identified a major problem for the ongoing future work of JILA. In fact, visiting the site and talking to the PIs revealed that the continuing excellence of JILA is seriously endangered by a combination of aging and lacking infrastructure. The panel was left with the impression that the successful future of the Quantum Physics Division at JILA is at best extremely close to—or, more likely, already past—the tipping point where the facility issues are able to be deferred while the institution continues being successful, because the ongoing work hinges critically on the availability of up-to-date infrastructure combined with modern and sufficient laboratory space.

Laboratory space is indeed an existential problem: most JILA buildings are more than 50 years old, and deferred maintenance in the $20 million range is significantly affecting daily work and resulting in periodic damage to equipment. In addition, presentations by division leadership indicated to the panel that an additional $200 million in capital funds for facility upgrades would barely bring the facilities up to peer institution standards (this estimate considers both new construction and renovation of current facilities). Given the competitive environment at the highest level in the fields of research represented by the Quantum Physics Division, this limitation places severe constraints on the organization. It is the opinion of the panel that the ability of the institution to hire the most qualified candidates for faculty positions has already been affected by substandard facilities and that this impact will only get worse, severely limiting the ability of the group to hire in anticipation of growth and future retirements. As the panel learned, JILA facilities upgrades and expansions are not captured in the NIST master plan, but JILA is in the CU master plan. As a consequence, NIST cannot simply address JILA’s problems on its own but

must rely on CU to do so in cooperation. Since problems have obviously arisen that have not been addressed, this could seriously endanger JILA’s capabilities in the future.

A lack of space, failing infrastructure (water leaking into the laboratories, failing air conditioners, etc.), and sub-standard safety conditions have already had a negative impact on research. This is a liability for the ongoing work and a serious danger for the future of the Quantum Physics Division and JILA. In particular, the recruitment of competitive PIs is being strongly hampered, especially because all space expansion ideas are unfunded plans, which are at present not even considered by CU nor by NIST. Therefore, in the current situation it is already impossible to compete with the best places to attract top people. This needs to be addressed very soon when considering the need to make new hires in view of the years of service of the PIs. The panel considers this situation to be an existential issue for JILA and its continuation as a center of excellence at the forefront of science. The panel has heard that several people indeed may be thinking of leaving because of the current situation.

General Working Conditions and Safety Issues

The limited space available in the laboratories presents a serious problem for the general working conditions in the laboratories and has a negative impact on safety issues, ranging from laser safety to the safe handling and storage of chemicals.

Safety culture and compliance issues are particularly challenging at JILA owing to differences in university and NIST safety requirements. The most obvious result of these inconsistencies is that safety conditions in laboratories are far from ideal. Because Colorado is not an Occupational Safety and Health Administration (OSHA) state, the university mandates compliance with state regulations. However, NIST, being a federal institution, is required to comply with OSHA regulations. This difference, together with vastly different safety cultures within the organizations, has resulted in substandard safety conditions regarding laser, electrical, chemical, cryogenic, laboratory egress, and general working conditions.

A specific example provides some insight into the complexities and severity of these issues of laboratory safety. The panel was made aware of inconsistencies in laser safety training between students and postdocs in JILA laboratories. While this was alarming, given International Electrotechnical Commission standard Class 3R/3B/4 lasers² in the laboratories the panel visited, the panel felt it was important to understand whether this was an inconsistency between laboratories or whether the issue was indicative of more systemic problems. Upon further investigation, the panel became aware of NIST’s ongoing efforts to improve laser safety on the JILA campus and how these efforts have resulted in safety improvements but also contribute to inconsistent training across JILA. Discussions between NIST and CU after a laser safety incident at JILA in 2021 led to the recent signing of a memorandum of understanding which documented the intention of the university to bring JILA up to American National Standards Institute (ANSI) laser safety standards. The first step in this process has been the establishment of a campus laser safety officer. The panel was both surprised to hear that the campus never had a laser safety officer—especially given the high fraction of laboratories within JILA containing International Electrotechnical Commission standard Class 3R/3B/4 lasers—and heartened that NIST and the university had emphasized this first step toward compliance with relevant safety standards. Lacking a laser safety officer has led to a patchwork approach to instituting adequate training across JILA laboratories, wherein NIST safety managers are conducting training sessions for students, postdocs, and faculty; furthermore, compliance tracking is clearly not yet where it needs to be. Again, it is clear that the intention by both organizations is to improve safety conditions, but the panel is concerned that there are no established timelines to reach compliance with the agreed-upon standards, nor are safety standards agreed upon across all areas. Furthermore, it is clear from discussions with NIST safety personnel that the intention is to use the safety memorandum to expand safety efforts into other areas; again, the panel’s concern is that there is no timeline set for implementation, nor even full agreement on the areas where conditions need to

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² See IEC 60825-1 Ed. 3.0 b:2014, https://webstore.iec.ch/publication/3587, last accessed January 17, 2024.

improve. Lastly, the facility issues mentioned elsewhere place severe constraints on the ability of the organizations to achieve safe conditions.

Recommendation 4-1: The National Institute of Standards and Technology’s Office of Facilities and Property Management and appropriate University of Colorado leadership should work together to solve the serious JILA space, infrastructure, and safety problems. The two organizations need to understand what is at risk and the urgency of the issue. A special task force with representatives of all stakeholders may be useful in putting focus on this problem and finding a timely solution.

Recommendation 4-2: The Physical Measurement Laboratory and the University of Colorado Boulder should jointly establish a clear and aggressive timeline to reach American National Standards Institute laser safety standards. The panel also recommends expanding the existing memorandum of understanding to establish acceptable standards and timelines for achieving improved and adequate safety compliance in those areas.

Diversity

A lack of diversity was noted by students and postdocs in nearly every measure of diversity, including gender, race, and identity. There were few indications of measures to improve diversity, and such measures are highly likely to be affected by the individual positions of the 29 JILA Fellows. The panel is concerned that a lack of attention to improving these conditions will affect JILA’s ability to bring in and, especially, retain highly qualified candidates and ensure that the teams are able to perform the highest-quality research.

EFFECTIVENESS OF DISSEMINATION EFFORTS

The division’s results are distributed in the very best journals, with extremely high impact factors. Between 2018 and now the division’s researchers have published more than 300 refereed papers and accumulated more than 60,000 citations, for an average h-index of 57.

Because of its involvement with UC, JILA is extremely well-posed to do public outreach. In fact, David Nesbitt is the “Chief Wizard and Program Director” of the extremely successful CU Wizards Program (https://www.colorado.edu/cuwizards). Each year, about 10 to 12 professors from different disciplines put on the wizard’s hat to present shows to students.

Stakeholder Needs

Quantum physics and the mysteries of state entanglement used to be the realm of the physicists and the more esoteric and advanced aspects of technology. However, in the past 5–10 years the panel has seen a remarkable growth in interest in quantum computing and quantum security at an international and highly competitive level. Historically the stakeholders of the Quantum Physics Division and JILA effort have been the community of fundamental scientists. All of this is changing at warp speed as fundamental quantum physics begins to invade all aspects of not only high technology but daily life.

A very surprising aspect of the growing interest in esoteric quantum physics from outside the field is the development of biomarker sensing using femtosecond frequency combs. This promises to lead to the inclusion of the medical community—and indeed of the general public as well as additional stakeholders—among those invested in quantum entanglement and other aspects of quantum physics.

Owing to the unique charter of JILA among NIST laboratories, a fundamental responsibility of Quantum Physics Division and JILA is to provide essential support to a broad spectrum of stakeholders through the recruiting and training of the next generation of top students and postdoctoral researchers in

quantum physics and quantum information science, broadly understood. Our textbooks and courses will need to be dramatically revised to accommodate this explosive change in quantum physics, and thus higher education will also be a stakeholder of Quantum Physics Division and JILA.