The mission of the Time and Frequency Division is to develop the highest-accuracy time and frequency measurements in support of commerce, research, and the general public.
The NIST 3-year plan (FY 2009-FY 2011) includes the following elements directly applicable to the mission of the Time and Frequency Division:11
Develop an all-optical clock for more precise time and frequency measurement;
Develop quantum logic clocks capable of providing improved time and frequency for the next generation of the Global Positioning System (GPS) and for tests of fundamental physics theories;
Improve environmental conditions within NIST’s Boulder, Colorado, research laboratories to enable production of the extremely accurate data needed by industry and academia and to support further progress in measurements related to high-frequency electronics, advanced materials characterized at the atomic level, subcellular forces, timing accuracy, and other areas; and
Make precision frequency measurements above 100 GHz (100 billion cycles per second), which are required for advanced commercial electronics, military systems, and homeland security.
The Time and Frequency Division is responsible for the realization and dissemination of the SI unit of time in the United States. The division provides a broad range of advanced measurement services and performs research and development for the future generations of time and frequency standards. In addition, the division is a key U.S. resource advancing quantum information processing.
This division has one of the most complete ranges of time and frequency research and metrology tools that can be combined for unique research and metrology. The division operates the following:
The most accurate primary standard (NIST-F1), the NIST time scale;
Femtosecond laser frequency comb systems to mediate the comparison across
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Time and Frequency Division DESCRIPTION OF THE DIVISION Mission The mission of the Time and Frequency Division is to develop the highest- accuracy time and frequency measurements in support of commerce, research, and the general public. Scope The NIST 3-year plan (FY 2009-FY 2011) includes the following elements directly applicable to the mission of the Time and Frequency Division:11 • Develop an all-optical clock for more precise time and frequency measurement; • Develop quantum logic clocks capable of providing improved time and frequency for the next generation of the Global Positioning System (GPS) and for tests of fundamental physics theories; • Improve environmental conditions within NIST’s Boulder, Colorado, research laboratories to enable production of the extremely accurate data needed by industry and academia and to support further progress in measurements related to high-frequency electronics, advanced materials characterized at the atomic level, subcellular forces, timing accuracy, and other areas; and • Make precision frequency measurements above 100 GHz (100 billion cycles per second), which are required for advanced commercial electronics, military systems, and homeland security. Projects The Time and Frequency Division is responsible for the realization and dissemination of the SI unit of time in the United States. The division provides a broad range of advanced measurement services and performs research and development for the future generations of time and frequency standards. In addition, the division is a key U.S. resource advancing quantum information processing. This division has one of the most complete ranges of time and frequency research and metrology tools that can be combined for unique research and metrology. The division operates the following: • The most accurate primary standard (NIST-F1), the NIST time scale; • Femtosecond laser frequency comb systems to mediate the comparison across 11 National Institute of Standards and Technology, 2008, Three-year Programmatic Plan for the National Institute of Standards and Technology, U.S. Department of Commerce: Fiscal Years 2009-2011, Gaithersburg, Maryland: National Institute of Standards and Technology. 51
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a factor-of-100,000 frequency range; • The narrowest linewidth laser for precision frequency measurement; • The unique mercury ion and logic clocks; and • The best capability for the phase noise measurement of microwave and millimeter-wave sources. This range of assets and experiments leads to unique scientific by-products, such as improvements by a factor of 10 in setting limits on the possible time variations in fundamental constants, and the most accurate tests of special and general relativity. NIST provides an array of services to a very broad user community in the United States: the NIST Internet Time Service is used more than 2.5 billion times every day; NIST radio station WWVB is widely used to synchronize commercial timekeeping devices to NIST time; the NIST Automated Computer Time Service helps industry meet Securities and Exchange Commission requirements to synchronize the time-stamping of hundreds of billions of dollars of electronic financial transactions to NIST time. The following international projects are noted as excellent examples of building goodwill for the United States: • The NIST-led project of developing an international network of common- view GPS receivers will enable time and frequency comparisons throughout the Inter-American Metrology System (SIM), which covers North, South, and Central America. Eventually, continuous comparisons will be enabled between the United States, Canada, Mexico, Argentina, Brazil, Costa Rica, Jamaica, Panama, Uruguay, and perhaps several other SIM member nations (already operational for the countries identified). This project was funded by the Department of State. • The NIST-developed Satellite Time Service for the North African and Middle Eastern region in a joint venture with the National Institute of Standards of Egypt. This project is sponsored by the U.S.-Egypt Joint Board on Scientific and Technological Cooperation. Staffing The division has done an excellent job of anticipating staffing needs by supporting students and postdoctoral researchers to participate in its projects. This approach provides a pool of trained talent, from which a large number of researchers continue employment at NIST. The work in this division is highly specialized, because time and frequency is a niche technology. Thus, specially trained staff are required to carry out the needed research. This need is generally met by a competent staff and a large contingent of visiting researchers, students, and postdoctoral fellows. The latter group typically is a major pool for the future staffing of the division. There has been notable improvement in the ability of the division to use guest scientists. A highly effective program in Boulder enables both foreign and domestic scientists to work at NIST Boulder on contract through a new scientific services company. Programs through several universities in Colorado enable collaborative work by foreign and domestic scientists with the division. 52
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Major Equipment, Facilities, Ancillary Support, and Resources The division has developed dedicated laboratories that support the National Time Standard (F1), the Next-Generation Standard (F2), the ion trapping laboratory, which has the special facility to achieve low-line-width lasers, and the phase metrology laboratory. The division is pursuing an East Coast-based low-frequency broadcast facility to augment the continuously broadcast standard time and frequency coverage of the continental United States. Several potential sites of decommissioned radio stations on the East Coast have been identified as possible sites for a second NIST low-frequency broadcast station, but no decision has been made on the most likely location. The cost of adapting such an existing facility for this project would be on the order of $9 million, compared with a new facility cost of $80 million. This is an excellent example of the intelligent use of a surplus facility to solve an important need at tremendous cost savings (equal to that of the new construction at Boulder). ASSESSMENT OF THE DIVISION The division programs focus on four principal thrusts: • The realization of national and international time and frequency standards with the greatest accuracy and precision; • The dissemination of time and frequency through a wide variety of measurement services directed to customers at all levels, from industrial and research customers with the most stringent needs to the general public with less exacting needs; • Research on future time and frequency standards and dissemination methods; and • Quantum computing with trapped ions, which evolved directly from research on new atomic clocks and which has become a major NIST-wide focus area. The division has established itself as a leader in these areas, providing a level of organizational performance (e.g., through demonstrated frequency accuracy and stability, scope and quantity of time-dissemination services, publication of scientific results) that exceeds that of any scientific laboratory in its field. The overall quality of the division’s work is very high (as demonstrated, for example, by the realization of a logic clock, the realization of the lowest uncertainty in a primary clock, and the demonstrated ability to disseminate time over the Internet on the widest basis); its staff is very talented and its technical approaches are effective. The division’s accomplishments, in the context of the criteria requested by the Director of NIST in his charge to the panel, are of high quality and directly relevant. The division’s inability to repair and maintain the facility in a timely manner and to an acceptable standard is a significant concern. This facility shortcoming creates gross inefficiencies and has the potential, through staff dissatisfaction and resulting attrition, to erode the present excellence. 53
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Technical Merit Relative to State of the Art With respect to NIST’s realization of the SI second, the division’s primary frequency standards have the best accuracy in the world, with a fractional frequency uncertainty of 4 × 10-16, and its time scale is one of the two best in terms of accuracy and stability as reflected by the NIST time scale contributions to the international time scale. In the area of measurement services, the division excels in a number of areas. Its remote time and frequency calibrations are the best with respect to accuracy and usability. NIST’s network time services are outstanding as well. For example, its Internet Time Service is the most heavily used network time protocol service in the world, logging 2.5 billion hits per day. The NIST radio stations also enjoy heavy use, and their accuracy and stability are the best. In addition, NIST’s time measurement and analysis service offers real-time, 15 ns uncertainty. With funding from the Department of State, NIST has expanded to SIM-time scale coordination in North, Central, and South America, generating international goodwill. In the area of phase noise metrology, NIST has unique capabilities, and its metrology is the leading edge. It is extending capability to 800 GHz, a capability that does not exist today. This extension is driven by advancing civilian and Department of Defense technology requirements. The division excels in several research and development activities: • For single-ion optical frequency standards, its mercury-ion standard is at the forefront, with a fractional frequency uncertainty of 1.6 × 10-17. • Its aluminum-ion logic clock is the second best, with a fractional frequency uncertainty of 2.4 × 10-17. • In the area of cold neutral atomic optical standards, calcium has excellent short-term stability and ytterbium lattice is among the best standards. The division’s research includes studies of these optical standards toward providing important high-stability reference clocks for intercomparison of the lowest-uncertainty clocks. • NIST’s femtosecond laser frequency combs have the most precise intercomparisons (1 × 10-19), and NIST has the top-performing octave-plus spanning combs. • In addition, NIST has demonstrated numerous firsts for chip-scale atomic sensors, including a chip-scale atomic clock and a chip magnetometer. In the area of quantum information processing: • NIST has the sole technology to demonstrate all seven DiVincenzo criteria for scalable quantum computing. • NIST has demonstrated the first of each of the following: single-atom quantum logic gate, deterministic entanglement, robust error correction, quantum teleportation of massive particles, and quantum Fourier transforms. 54
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Adequacy of Infrastructure The infrastructure and facilities of the Time and Frequency Division have shown improvement since 2005. A central HVAC facility is being installed to provide improved environmental controls within the existing buildings. A power-conditioning unit is being installed to improve the reliability and quality of the alternating current power to the laboratories onsite. The room in which the new time standard (F2) is being assembled is a significant improvement over what housed the current F1 in 2005. A new laboratory building to support the entire NIST Boulder facility has been funded, and construction bids have been solicited. There remains, however, the problem of the inability to repair and maintain the facility in a timely manner and to an acceptable standard. This matter affects employee efficiency and morale. The division’s staff and management have noted that an increasingly unhealthy fraction of the time and energy of scientists is consumed with various administrative burdens related to information technology security, procurement, physical security, repeated inventories, required training on obscure administrative issues, and many other distractions. NIST should examine ways to comply with the governing laws, regulations, and mandates while minimizing the distraction of the scientists from their mission and fundamental enterprise and maintaining productivity and morale. Achievement of Objectives and Impact The stated objectives of the Time and Frequency Division are as follows: Realize the SI second and UTC(NIST)12 with the greatest possible accuracy • and precision as the basis of all division measurement services; • Provide time and frequency measurement services addressing a broad range of needs, from the most demanding industry and research customers to the general public, based on UTC(NIST); • Perform research and development for the future generations of time and frequency standards, measurement services, and distribution systems; and • Perform research on quantum information processing, in support of NIST- wide goals and to improve time and frequency standards. The division shows a high level of achievement of these objectives, as demonstrated by the following: • The best realization in the world of the SI second; • Web clock supporting 2.5 billion hits per day; • Widely used radio station transmissions and time measurement and analysis services, extended to the international community; • Unique phase noise measurement capability, extending to 800 GHz; • Research in ion and cold atomic clocks with unprecedented precision and 12 UTC(NIST) is Coordinated Universal Time. 55
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stability; • Research in laser frequency combs; and • Research in the chip-scale atomic sensor. CONCLUSIONS The technical work of the Time and Frequency Division is excellent and serves as a model for other laboratories in the field. The physical facilities in which this work is performed have received modest improvements over the past 3 years, but these facilities need further improvement. Initiatives to construct a new laboratory, appropriate for the work and technology of the division, are laudable; this construction should be completed as planned. In the meantime, NIST should ensure that projects to repair and improve electric power and other utilities at the NIST Boulder site are effectively prioritized and completed on time and to specification. The impacts of increasing administrative burdens, poor facilities, and other distractions are severe enough that highly productive and skilled scientists within the division are looking for opportunities outside NIST. The success of the division depends on the ability of the organization to attract and retain the best scientists; such individuals want to work in an environment where administrative issues, IT security, facilities, and other issues are sufficiently minimal distractions so as not to hinder their research and creativity. Repeated reports from staff have indicated that in recent years NIST has become substantially more encumbered by these burdens and distractions. Such reports introduce the significant concern that the long-term scientific leadership and productivity of the division will be compromised by the inability to attract and retain the best scientists, who will seek opportunities where they are not overly encumbered by such administrative issues. 56