An Assessment of the National Institute of Standards and Technology Physics Laboratory: Fiscal Year 2010 (2010)

The goal of the Atomic Physics Division is to investigate and exploit quantum behavior and interactions of atomic matter and radiation. The strategy for achieving the division’s mission is to develop and apply atomic-physics and condensed-matter research methods, particularly those making novel use of electromagnetic fields, to achieve fundamental advances in measurement science—including measurement at and beyond the standard quantum limit.

The Atomic Physics Division, located at NIST’s Gaithersburg, Maryland, campus, has 3 NIST fellows, 27 scientists/engineers, 1 technician, 74 NIST associates (the associates category includes contractors, NRC postdoctoral researchers, foreign guest researchers, and guest researchers/workers from universities and industry), and 5 administrative support staff, as of January 2010. Its FY 2009 budget was about $15.4 million, 86 percent of which was scientific and technical research services (STRS) internal funding.

The scope of the Atomic Physics Division includes the following four strategic elements.

1. To advance the understanding and applications of cold atomic matter, including the study of many-body quantum systems, exotic states of matter, atomic analogs of condensed-matter systems, metrology of and with cold atoms, and quantum information;

2. To advance measurement science at the atomic and nanometer scale, focusing on precision optical metrology, quantum optics of nanoscale systems, nanoscale devices at the quantum limit, and nano-optical systems;

3. To explore fundamental aspects of the quantum nature of light and its interaction with quantum matter and to develop applications relating to metrology and other areas of NIST’s mission, including measurement at and beyond the standard quantum limits; and

4. To measure, calculate, critically compile, and disseminate reference data on atomic structure and fundamental constants in support of basic research, commercial development, and national priorities.

The current effort in cold atomic matter focuses on the physics and applications of laser cooling and the electromagnetic trapping of neutral particles, the manipulation of ultracold atoms and Bose-Einstein condensates, and the creation of exotic states of matter through control of ultracold atoms. It includes both fundamental studies, such as the investigation of superfluidity, and applied studies, including quantum information processing and the engineering of synthetic charge along with synthetic electric and magnetic fields for neutral atoms.

The pioneering development of laser cooling and trapping techniques, much of which was done at NIST, allows exquisite control over the motion of atoms. Such control has been exploited to build more precise atomic clocks and other precision-measurement devices at NIST and elsewhere. These techniques also enable the study and manipulation of atoms and molecules under conditions in which their quantum behavior dominates. This research has revolutionized the field of matter-wave optics, given rise to the field of quantum simulation, and now allows the simulation of the behavior of charged particles using neutral atoms.

The effort in nanoscale and quantum metrology focuses on developing and exploiting precision metrology at the interface between atomic and nanoscale systems. Systems under study include quantum dots and wires, optical microcavities, the quantum optics of nanosystems, metallic nanoparticles, and those with nanoscale features induced on surfaces by highly charged ions. Such systems arise in advanced 193 nm and 157 nm lithography, plasma etching of semiconductor wafers, nanolasers, detectors, biomarkers and sensors, nanomaterials, quantum devices, and quantum information.

The research in this effort combines theory and experiment. Theory is used to extend the fundamental understanding of systems at the atomic-nanoscale interface as necessary to interpret experiments, to explore new applications in nanoscale and quantum technologies, and to motivate new and enhanced precision metrology. The researchers are developing the theoretical understanding needed to create nano-optics structures that will be needed in emerging quantum and nanoscale technologies.

The strategic element involving the quantum behavior of light and matter focuses on entangled states of light and analogous states of matter. These quantum features are studied in situations that range from the generation of quantum light in atomic vapors and condensed-matter systems, to the effect of quantum light on quantum degenerate atomic gases, to the behavior of mechanical oscillators at the quantum level.

The goals of this effort include the following: the evaluation of quantum light, atoms, and fabricated micromechanical systems for metrology beyond the standard quantum limits; the development of quantum information transfer between different

physical qubit platforms according to which ones are most appropriate for a given function; and the fundamental study of quantum phenomena, such as measurement and the quantum-classical interface.

The aim of the strategic element on critically evaluated atomic data is to maintain an authoritative and publicly accessible source of atomic data and related fundamental constants. Two examples of databases maintained by this group are the Fundamental Constants database and the Atomic Spectra database, but there are many other similar databases that address specific areas of high impact. Some of the data in the NIST databases are compiled from the open scientific literature. NIST adds great value through the process of critical compilation. Other data are generated by experiments at NIST, such as measurements of highly charged ions with the NIST Electron Beam Ion Trap (EBIT), the development of standard spectral sources for calibration of the next generation of space- and ground-based telescopes, and the development of new measurement platforms for improved determination of fundamental constants. Theoretical calculations also address needs for atomic data and for the improvement of fundamental constants. Theoretical work includes atomic structure calculations, studies of fundamental constants, and kinetic modeling of highly charged ions and high-energy-density plasmas.

As stated above, the mission of the Atomic Physics Division is to investigate and exploit the quantum behavior and interaction of atomic matter and radiation. The division succeeds in reflecting this mission. Its major projects strike a healthy balance between fundamental studies that yield new knowledge which may lead to new technologies that are important to maintaining U.S. leadership economically and scientifically, and applied studies that target high-priority needs of industry, the energy community, and the space astronomy program. The work in the division also has important positive impact on issues relevant to national security.

The major accomplishments of the division since the previous assessment, in 2008, include both institutional progress and technological accomplishments. Examples of institutional progress include the following:

• The NIST Quantum Information Program, started in 2000, is a cross-laboratory effort in quantum information science. The scope of this program was further expanded in 2006 with the establishment of the Joint Quantum Institute, a partnership of NIST with the University of Maryland and the Laboratory for Physical Sciences of the National Security Agency to study coherent quantum phenomena and quantum information science. The JQI has had and will continue to have a profound and lasting positive effect on the research efforts of the division.

• NIST is taking a leadership role in the U.S. government in delineating the opportunities for quantum information science and technology to address

national priorities. This effort includes ultrasecure encryption, code breaking, database searching, weather forecasting, drug design, and the solution of many other challenging scientific and technological problems. The chief of the Atomic Physics Division also serves as the co-director of the JQI and as coordinator of the NIST Quantum Information Science Program, and currently also leads a federal initiative in quantum information science in the Office of Science and Technology Policy.

• The Atomic Spectroscopy Group, which received funds to enhance the Atomic Data Center, has received an increase in its level of base funding.

The technological accomplishments of the division are strongly aligned with the mission of the laboratory and are of high technical merit. Technological accomplishments in the division since the previous NRC assessment of the Physics Laboratory include the following:

• Theorists in the Atomic Physics Division provided critical theoretical support for experiments at JILA that produced for the first time a dense sample of ultracold, 330 nK ⁴⁰K⁸⁷Rb polar molecules in their ground state of electronic, rotational, and vibrational motion. This work, which is important because it could provide new phases of matter for quantum information and quantum control, provided an important part of a successful Multi-University Research Initiative proposal from JQI funded by the Air Force Office of Scientific Research.

• NIST scientists have developed a technique for generating entangled light by four-wave mixing in atomic vapors. It produces “twin beams” of light that are more closely correlated than for any classical sources. One particularly useful feature of this technique is that entangled light can easily be made in multiple spatial modes. That is, images with quantum correlations can be produced. Pixel by pixel, the light in these pairs of images is correlated at levels better than the shot noise for the photon numbers involved.

• NIST scientists have used an Electron Beam Ion Trap to produce and study highly charged ions of heavy elements that are relevant to the development of controlled fusion energy. Atoms of the heavy elements hafnium, tantalum, tungsten, and gold were stripped of 60 or more electrons and held in the EBIT while their radiative properties and atomic structure were studied. Experimental observations in combination with sophisticated plasma kinetic modeling uncovered combinations of soft-x-ray emission lines that are suitable for use by fusion scientists in analyzing the super-hot plasmas in fusion-energy devices.

Following is the panel’s assessment of the overall quality of the Atomic Physics Division (including opportunities for improvement) in terms of the three criteria as requested by the NIST Director (see Chapter 1).

The area of atom cooling and trapping was pioneered at NIST, leading to a Nobel Prize in 1997. This group also pioneered the confinement of cold atoms in optical lattices formed by the interaction of atoms with a standing wave of light. The trapped atoms are being explored as a possible route to quantum computation and for the quantum simulation of problems of interest in condensed matter. This work is among the best in its field.

The efforts on quantum metrology are addressing interesting issues with the potential for transformative advances. They are well integrated with other efforts in related areas around the world.

The work on entangling photons in quantum dots is among the best in the world. It is potentially extremely important for quantum communication and information applications.

The atomic data evaluated and compiled by the Atomic Spectroscopy Data Center provide a definitive and accessible source of atomic spectral data for applications in areas including astronomy and fusion research. The effort could be improved even further by integrating state-of-the-art information technology advances into the effort.

The Atomic Physics Division has had one staff member depart and has made two promising hires of permanent staff over the past 2 years. One-third of the permanent scientific staff was new to the division over the course of the past decade. The total number of permanent staff has been constant in recent years even though the level of funding increased during that time; this is because of the inflation, not included in the division’s base budget, that increased the cost to support each investigator. An increasingly important problem is that salaries at NIST are becoming more and more uncompetitive with those paid by major research universities, particularly for senior scientists.

The JQI has had an extremely positive impact on the number of graduate students and postdoctoral researchers contributing to the scientific efforts of the division. The JQI effort effectively leverages the expertise of the Atomic Physics Division staff, exposing

young physicists to the important missions of the laboratory as aligned with national priorities and increasing the overall impact of the division.

One concern is that hiring qualified non-U.S. citizen scientists who have green cards is extremely difficult, slow, and time-consuming. To remain competitive on a global scale, it is critically important for the division to be able to hire the most highly qualified scientists.

The status of equipment, facilities, and ancillary support and resources in the division is good overall, but some of the buildings housing experiments in the division are in need of renovation. Laboratory management is aware of infrastructure needs and is working hard to address them.

The current equipment of the division is state of the art. The older general-purpose laboratories do have problems, particularly in the areas of humidity control (which leads to serious condensation problems), temperature control, and air quality. The other facilities are excellent and are well maintained. The Advanced Measurement Laboratory building provides state-of-the-art facilities for the Cold Atomic Matter activity and for parts of the Nanoscale and Quantum Metrology activity. These activities receive significant outside funding—a recognition of the importance of the research to outside funding agencies. This laboratory is maintained and used at a high level. The Joint Quantum Institute is constructing a new building on the campus of the University of Maryland at College Park that will provide new laboratory space for this group.

The Atomic Physics Division is doing an excellent job of achieving its objectives. The high impact of its work is demonstrated on multiple fronts, including the large number of highly prestigious awards given to investigators in the division and the large number of articles published in high-impact journals.⁵ In addition, the use of the Atomic Spectroscopy Data Center continues to increase, with more than 45,000 hits per month over the past year. The impact of this division is also seen in the formal training provided by division staff for the 27 postdoctoral fellows (of which 23 are associated with the JQI) and the 19 graduate students (18 are associated with the JQI). The number of

postdoctoral fellows and students has increased significantly owing to the new partnership with the JQI. This training of future scientists in the mission-oriented work aligned with national priorities is a particularly valuable contribution. Every effort should be made to support the factors that encourage such training, particularly financial support for the new Joint Quantum Institute.

The Cold Atomic Matter team continues to make world-leading breakthroughs. One recent example is the generation of a synthetic vector potential for cold atoms.⁶ This work is important because it enables the cold atom system to be used to simulate the behavior of charged particles in the presence of a strong magnetic field, potentially enabling a new level of understanding of the properties of complex materials.

The Nanoscale and Quantum Metrology team’s use of highly ionized atoms to control properties of tunnel junctions is novel. The work on the complementary metal oxide semiconductor-compatible process for silicon devices for low-noise applications is potentially extremely important.

The team working on Quantum Behavior of Light and Matter has made important breakthroughs. These include the demonstration of entanglement between photons from different sources and entanglement of nanomechanical and optical degrees of freedom.

The NIST work in the area of Critically Evaluated Atomic Data sets the standard for the world. The critically evaluated data from the scientific literature and targeted original investigations that are combined and made available to the public provide a definitive standard in this area.

The technical merit of all of the groups in the Atomic Physics Division continues at a very high level, driving the current state of the art in the relevant research areas. The Joint Quantum Institute is a major success and a powerful addition to the research enterprise at NIST. The remarkable advances in quantum information, quantum measurement, and quantum control are potentially revolutionary for science, technology,

and national security. One concern is that hiring qualified non-U.S. citizen scientists who have green cards is extremely difficult, slow, and time-consuming.