The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Helen S. Margolis - One of the best experts on this subject based on the ideXlab platform.
-
Optical Frequency Standards and clocks.
Contemporary Physics, 2010Co-Authors: Helen S. MargolisAbstract:Optical Frequency Standards based on single trapped ions or ensembles of neutral atoms have recently demonstrated stability and accuracy superior to that of the current generation of microwave primary Frequency Standards, with significant potential for further improvements. When combined with femtosecond optical Frequency combs, these Standards can be operated as optical clocks generating a direct microwave output signal, raising the possibility of a future redefinition of the second. In this introductory review, the principles of operation, current state-of-the-art performance and applications of optical Frequency Standards and clocks are described and the further developments that are likely to occur over the next few years are considered.
-
Trapped Ion Optical Frequency Standards
Physica Scripta, 2004Co-Authors: Patrick Gill, Geoffrey P. Barwood, H. A. Klein, G. Huang, S. A. Webster, P.j. Blythe, K. Hosaka, S. N. Lea, Richard C. Thompson, Helen S. MargolisAbstract:Weak transitions in single cold trapped ions are highly reproducible as optical Frequency Standards on account of the high quality factors and stabilities achievable. In recent years, there has been a quickening pace in the development of these optical Frequency Standards, particularly due to the emergence of femtosecond laser combs for relating the optical Frequency directly to the Cs standard. This paper reports progress on optical Frequency Standards based on the quadrupole transition in a single cold ion of 88Sr+ and the octupole transition in a single cold ion of 171Yb+.
-
Trapped ion optical Frequency Standards
Measurement Science and Technology, 2003Co-Authors: Patrick Gill, Geoffrey P. Barwood, H. A. Klein, G. Huang, S. A. Webster, P.j. Blythe, K. Hosaka, S. N. Lea, Helen S. MargolisAbstract:Optical Frequency Standards based on narrow absorptions in laser-cooled single trapped ions have recently begun to demonstrate stabilities that are competitive with cold atom fountain microwave Standards. This paper presents a short review of the wider state-of-the-art development of these single cold trapped ion Frequency Standards, coupled with a more detailed account of recent results achieved at National Physical Laboratory in respect of single ion systems based on 88Sr+, 87Sr+ and 171Yb+. Narrow linewidth data for the optical clock quadrupole and octupole transitions respectively at 674 nm in 88Sr+ and 467 nm in 171Yb+, are presented, together with a discussion of current systematics and future projections. The potential for optical clock operation is outlined.
-
Trapped ion optical Frequency Standards and metrology
2003 Digest of LEOS Summer Topical Meeting (Cat. No.03TH8701), 1Co-Authors: Helen S. Margolis, H. A. Klein, G. Huang, P.j. Blythe, K. Hosaka, S. N. Lea, G. P. Barwood, P. Gill, S. A. WebsterAbstract:Forbidden transitions in single laser-cooled trapped ions provide highly stable and accurate references for optical Frequency Standards. This paper describes work on strontium and ytterbium ion optical Frequency Standards currently under development at NPL.
Wayne M. Itano - One of the best experts on this subject based on the ideXlab platform.
-
Primary Atomic Frequency Standards at NIST.
Journal of research of the National Institute of Standards and Technology, 2001Co-Authors: D.b. Sullivan, James C. Bergquist, Thomas E. Parker, Steven R. Jefferts, John J. Bollinger, R. E. Drullinger, Wayne M. Itano, W.d. Lee, D. M. Meekhof, Fred L. WallsAbstract:The development of atomic Frequency Standards at NIST is discussed and three of the key Frequency-standard technologies of the current era are described. For each of these technologies, the most recent NIST implementation of the particular type of standard is described in greater detail. The best relative standard uncertainty achieved to date for a NIST Frequency standard is 1.5×10(-15). The uncertainties of the most recent NIST Standards are displayed relative to the uncertainties of atomic Frequency Standards of several other countries.
-
Optical Frequency Standards and measurements
IEEE Journal of Quantum Electronics, 2001Co-Authors: Leo W. Hollberg, Scott A Diddams, E. A. Curtis, Christopher W. Oates, Eugene Ivanov, Thomas Udem, Hugh Robinson, J.c. Bergquist, Robert J. Rafac, Wayne M. ItanoAbstract:We describe the performance characteristics and Frequency measurements of two high-accuracy high-stability laser-cooled atomic Frequency Standards. One is a 657-nm (456-THz) reference using magneto-optically trapped Ca atoms, and the other is a 282-nm (1064-THz) reference based on a single Hg/sup +/ ion confined in an RF-Paul trap. A femtosecond mode-locked laser combined with a nonlinear microstructure fiber produces a broad and stable comb of optical modes that is used to measure the frequencies of the reference lasers locked to the atomic Standards. The measurement system is referenced to the primary Frequency standard NIST F-1, a Cs atomic fountain clock. Both optical Standards demonstrate exceptional short-term instability (/spl ap/5/spl times/10/sup -15/ at 1 s), as well as excellent reproducibility over time. In light of our expectations for the future of optical Frequency Standards, we consider the present performance of the femtosecond optical Frequency comb, along with its limitations and future requirements.
-
Atomic ion Frequency Standards
Proceedings of the IEEE, 1991Co-Authors: Wayne M. ItanoAbstract:The history and status of trapped-ion Frequency Standards are reviewed. In a trapped-ion Frequency standard, the Frequency of an oscillator is servoed to a resonance which corresponds to a transition between two energy levels of an atomic ion. The ions are suspended in space by a combination of electric and magnetic fields. In a conventional rubidium cell, the atoms are surrounded by a buffer gas having a pressure of about 10/sup 3/ Pa (approximately 10 torr). In an ion trap, the ions are held either in a vacuum or in a low-pressure buffer gas (less than 10/sup -3/ Pa). In an atomic beam, the atoms also move through a vacuum, without collisions. However, the time available for interaction with the electromagnetic field is limited to their flight time through the apparatus, usually about 10 ms or less. Trapped ions can be observed for much longer periods. Consequently clocks based on ions trapped in electromagnetic fields portend orders-of-magnitude improvement in the development of new Frequency Standards. Prospects for future Standards are discussed. >
Amar C. Vutha - One of the best experts on this subject based on the ideXlab platform.
-
Optical Frequency Standards for gravitational wave detection using satellite Doppler velocimetry
New Journal of Physics, 2015Co-Authors: Amar C. VuthaAbstract:Gravitational waves (GWs) imprint apparent Doppler shifts on the Frequency of photons propagating between an emitter and detector of light. This forms the basis of a method to detect GWs using Doppler velocimetry between pairs of satellites. Operating in the micro-hertz to milli-hertz gravitational Frequency band, this method could lead to the direct detection of GWs. The crucial component in such detectors is the Frequency standard on board the emitting and receiving satellites. Recent developments in atomic Frequency Standards have led to devices that are approaching the sensitivity required to detect GWs from astrophysically interesting sources. The sensitivity of satellites equipped with optical Frequency Standards for Doppler velocimetry is examined, and a design for a robust, space-capable optical Frequency standard is presented.
-
optical Frequency Standards for gravitational wave detection using satellite doppler velocimetry
arXiv: Atomic Physics, 2015Co-Authors: Amar C. VuthaAbstract:Gravitational waves imprint apparent Doppler shifts on the Frequency of photons propagating between an emitter and detector of light. This forms the basis of a method to detect gravitational waves using Doppler velocimetry between pairs of satellites. Such detectors, operating in the milli-hertz gravitational Frequency band, could lead to the direct detection of gravitational waves. The crucial component in such a detector is the Frequency standard on board the emitting and receiving satellites. We point out that recent developments in atomic Frequency Standards have led to devices that are approaching the sensitivity required to detect gravitational waves from astrophysically interesting sources. The sensitivity of satellites equipped with optical Frequency Standards for Doppler velocimetry is examined, and a design for a robust, space-capable optical Frequency standard is presented.
S. N. Lea - One of the best experts on this subject based on the ideXlab platform.
-
limits to time variation of fundamental constants from comparisons of atomic Frequency Standards
European Physical Journal-special Topics, 2008Co-Authors: S. N. LeaAbstract:Comparisons between Frequency Standards based on optical and microwave transitionsin atoms and ions currently provide the most stringent laboratory limitson present-day local variation of the fundamental constants.This paper discusses the sensitivity of these Frequency Standards to variation ofthe electromagnetic and strong interactions, summarises the constraints onvariation of these interactions which can be obtained from currently-available data, and discusses the magnitude of improvements in these limits which is anticipated fromexperiments currently underway.
-
limits to time variation of fundamental constants from comparisons of atomic Frequency Standards
Reports on Progress in Physics, 2007Co-Authors: S. N. LeaAbstract:Time variation of the fundamental constants is one manifestation of the violation of Einstein's Equivalence Principle required by theories uniting gravitation with the strong and electroweak interactions.The rapid progress in the development of atomic Frequency Standards based on optical transitions is leading to ever more stringent constraints on time variation of the fine structure constant, α, which is the coupling constant of the electromagnetic interaction, and to quantities such as nuclear g-factors and mass ratios, which depend on the strong interaction. Absolute Frequency measurements of these optical Frequency Standards currently place a limit on present-day time variation of the fine structure constant of (−4 ± 4) parts in 1016 per year. There are good prospects for an improvement of two orders of magnitude in this limit by means of direct Frequency comparisons between optical Frequency Standards.
-
Trapped Ion Optical Frequency Standards
Physica Scripta, 2004Co-Authors: Patrick Gill, Geoffrey P. Barwood, H. A. Klein, G. Huang, S. A. Webster, P.j. Blythe, K. Hosaka, S. N. Lea, Richard C. Thompson, Helen S. MargolisAbstract:Weak transitions in single cold trapped ions are highly reproducible as optical Frequency Standards on account of the high quality factors and stabilities achievable. In recent years, there has been a quickening pace in the development of these optical Frequency Standards, particularly due to the emergence of femtosecond laser combs for relating the optical Frequency directly to the Cs standard. This paper reports progress on optical Frequency Standards based on the quadrupole transition in a single cold ion of 88Sr+ and the octupole transition in a single cold ion of 171Yb+.
-
Trapped ion optical Frequency Standards
Measurement Science and Technology, 2003Co-Authors: Patrick Gill, Geoffrey P. Barwood, H. A. Klein, G. Huang, S. A. Webster, P.j. Blythe, K. Hosaka, S. N. Lea, Helen S. MargolisAbstract:Optical Frequency Standards based on narrow absorptions in laser-cooled single trapped ions have recently begun to demonstrate stabilities that are competitive with cold atom fountain microwave Standards. This paper presents a short review of the wider state-of-the-art development of these single cold trapped ion Frequency Standards, coupled with a more detailed account of recent results achieved at National Physical Laboratory in respect of single ion systems based on 88Sr+, 87Sr+ and 171Yb+. Narrow linewidth data for the optical clock quadrupole and octupole transitions respectively at 674 nm in 88Sr+ and 467 nm in 171Yb+, are presented, together with a discussion of current systematics and future projections. The potential for optical clock operation is outlined.
-
Trapped ion optical Frequency Standards and metrology
2003 Digest of LEOS Summer Topical Meeting (Cat. No.03TH8701), 1Co-Authors: Helen S. Margolis, H. A. Klein, G. Huang, P.j. Blythe, K. Hosaka, S. N. Lea, G. P. Barwood, P. Gill, S. A. WebsterAbstract:Forbidden transitions in single laser-cooled trapped ions provide highly stable and accurate references for optical Frequency Standards. This paper describes work on strontium and ytterbium ion optical Frequency Standards currently under development at NPL.
Patrick Gill - One of the best experts on this subject based on the ideXlab platform.
-
Optical Frequency Standards
Metrologia, 2005Co-Authors: Patrick GillAbstract:The evolution of atomic Frequency Standards since Essen's atomic clock fifty years ago has been considerable both in respect of microwave and optical Standards. In particular, the development of trapping and laser cooling techniques for both atoms and ions has played a major role. This paper reviews the status of the development of single cold trapped ion and cold trapped atom optical Frequency Standards. Recent results show comb measurements of trapped ion optical Frequency Standards with accuracies close to Cs fountain limited operation. The factors affecting future stability and reproducibility are discussed. The opportunities for future Standards capable of approaching reproducibility at the 10?18 level are outlined, together with the likely limitations arising.
-
Trapped Ion Optical Frequency Standards
Physica Scripta, 2004Co-Authors: Patrick Gill, Geoffrey P. Barwood, H. A. Klein, G. Huang, S. A. Webster, P.j. Blythe, K. Hosaka, S. N. Lea, Richard C. Thompson, Helen S. MargolisAbstract:Weak transitions in single cold trapped ions are highly reproducible as optical Frequency Standards on account of the high quality factors and stabilities achievable. In recent years, there has been a quickening pace in the development of these optical Frequency Standards, particularly due to the emergence of femtosecond laser combs for relating the optical Frequency directly to the Cs standard. This paper reports progress on optical Frequency Standards based on the quadrupole transition in a single cold ion of 88Sr+ and the octupole transition in a single cold ion of 171Yb+.
-
Trapped ion optical Frequency Standards
Measurement Science and Technology, 2003Co-Authors: Patrick Gill, Geoffrey P. Barwood, H. A. Klein, G. Huang, S. A. Webster, P.j. Blythe, K. Hosaka, S. N. Lea, Helen S. MargolisAbstract:Optical Frequency Standards based on narrow absorptions in laser-cooled single trapped ions have recently begun to demonstrate stabilities that are competitive with cold atom fountain microwave Standards. This paper presents a short review of the wider state-of-the-art development of these single cold trapped ion Frequency Standards, coupled with a more detailed account of recent results achieved at National Physical Laboratory in respect of single ion systems based on 88Sr+, 87Sr+ and 171Yb+. Narrow linewidth data for the optical clock quadrupole and octupole transitions respectively at 674 nm in 88Sr+ and 467 nm in 171Yb+, are presented, together with a discussion of current systematics and future projections. The potential for optical clock operation is outlined.
-
Development of acetylene-stabilized diode laser Frequency Standards
The 15th Annual Meeting of the IEEE Lasers and Electro-Optics Society, 1Co-Authors: C.s. Edwards, Geoffrey P. Barwood, Patrick Gill, W. R. C. RowleyAbstract:Two semiconductor laser Frequency Standards for 1.55 /spl mu/m telecommunications applications have been developed, based on Doppler-free /sup 13/C/sub 2/H/sub 2/ spectra. Preliminary results on Frequency stability, reproducibility and systematic effects will be presented.
