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Sample records for atomic clock application

  1. Compact, Continuous Beam Cold Atom Clock for Space Applications

    NASA Astrophysics Data System (ADS)

    Buell, Walter

    2000-06-01

    Highly stable atomic frequency standards are of increasing importance for a variety of space applications, ranging from communication to navigation and time transfer to tests of fundamental science. The requirements for an atomic clock vary significantly depending on the application, and for many space systems compactness and robust design are at a premium and stability dominates over absolute accuracy. We report on progress with our design for a compact Cs beam atomic clock suitable for space applications and featuring a cold atomic beam source based on a single beam, conical mirror MOT with a hole at the apex to produce a low velocity high flux atomic beam. This cold atomic beam is then used in a laser-pumped Ramsey clock, with the clock signal derived from either a microwave C-field or alternatively by Raman resonance between the Ramsey fields. The cold atom source produces a continuous beam, which relaxes requirements on the local oscillator as compared with pulsed sources. In order to reduce light shifts from the MOT light and improve signal-to-noise, the atomic beam is optically deflected and transversely cooled upon exiting the MOT's conical reflector. We estimate that the shot-noise-limited stability achievable with this physics package can be two to three orders of magnitude better than current cesium beam atomic clocks used in space applications. We present our latest experimental progress towards a working frequency standard.

  2. Compact atomic clocks and stabilised laser for space applications

    NASA Astrophysics Data System (ADS)

    Mileti, Gaetano; Affolderbach, Christoph; Matthey-de-l'Endroit, Renaud

    2016-07-01

    We present our developments towards next generation compact vapour-cell based atomic frequency standards using a tunable laser diode instead of a traditional discharge lamp. The realisation of two types of Rubidium clocks addressing specific applications is in progress: high performance frequency standards for demanding applications such as satellite navigation, and chip-scale atomic clocks, allowing further miniaturisation of the system. The stabilised laser source constitutes the main technological novelty of these new standards, allowing a more efficient preparation and interrogation of the atoms and hence an improvement of the clock performances. However, before this key component may be employed in a commercial and ultimately in a space-qualified instrument, further studies are necessary to demonstrate their suitability, in particular concerning their reliability and long-term operation. The talk will present our preliminary investigations on this subject. The stabilised laser diode technology developed for our atomic clocks has several other applications on ground and in space. We will conclude our talk by illustrating this for the example of a recently completed ESA project on a 1.6 microns wavelength reference for a future space-borne Lidar. This source is based on a Rubidium vapour cell providing the necessary stability and accuracy, while a second harmonic generator and a compact optical comb generated from an electro-optic modulator allow to transfer these properties from the Rubidium wavelength (780nm) to the desired spectral range.

  3. Atomic Clocks

    NASA Astrophysics Data System (ADS)

    Wynands, Robert

    Time is a strange thing. On the one hand it is arguably the most inaccessible physical phenomenon of all: both in that it is impossible to manipulate or modify—for all we know—and in that even after thousands of years mankind's philosophers still have not found a fully satisfying way to understand it. On the other hand, no other quantity can be measured with greater precision. Today's atomic clocks allow us to reproduce the length of the second as the SI unit of time with an uncertainty of a few parts in 1016—orders of magnitude better than any other quantity. In a sense, one can say [1

  4. Optical atomic clocks and metrology

    NASA Astrophysics Data System (ADS)

    Ludlow, Andrew

    2014-05-01

    The atomic clock has long demonstrated the capability to measure time or frequency with very high precision. Consequently, these clocks are used extensively in technological applications such as advanced synchronization or communication and navigation networks. Optical atomic clocks are next- generation timekeepers which reference narrowband optical transitions between suitable atomic states. Many optical time/frequency standards utilize state-of-the-art quantum control and precision measurement. Combined with the ultrahigh quality factors of the atomic resonances at their heart, optical atomic clocks have promised new levels of timekeeping precision, orders of magnitude higher than conventional atomic clocks based on microwave transitions. Such measurement capability enables and/or enhances many of the most exciting applications of these clocks, including the study of fundamental laws of physics through the measurement of time evolution. Here, I will highlight optical atomic clocks and their utility, as well as review recent advances in their development and performance. In particular, I will describe in detail the optical lattice clock and the realization of frequency measurement at the level of one part in 1018. To push the performance of these atomic timekeepers to such a level and beyond, several key advances are being explored worldwide. These will be discussed generally, with particular emphasis on our recent efforts at NIST in developing the optical lattice clock based on atomic ytterbium.

  5. Higher Pole Linear Traps for Atomic Clock Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    2000-01-01

    We investigate experimentally and theoretically higher pole linear ion traps for frequency standard use. We have built a 12-pole trap and have successfully loaded ions into it from a linear quadrupole trap. By solving the Boltzmann equation describing large ion clouds where space charge interactions are important, we show that clock frequency changes due to ion number fluctuations are much smaller in ion clocks based multipole traps than comparable clocks based on quadrupole linear traps.

  6. VCSELs for atomic clocks

    NASA Astrophysics Data System (ADS)

    Serkland, Darwin K.; Peake, Gregory M.; Geib, Kent M.; Lutwak, Robert; Garvey, R. Michael; Varghese, Mathew; Mescher, Mark

    2006-02-01

    The spectroscopic technique of coherent population trapping (CPT) enables an all-optical interrogation of the groundstate hyperfine splitting of cesium (or rubidium), compared to the optical-microwave double resonance technique conventionally employed in atomic frequency standards. All-optical interrogation enables the reduction of the size and power consumption of an atomic clock by two orders of magnitude, and vertical-cavity surface-emitting lasers (VCSELs) are preferred optical sources due to their low power consumption and circular output beam. Several research teams are currently using VCSELs for DARPA's chip-scale atomic clock (CSAC) program with the goal of producing an atomic clock having a volume < 1 cm^3, a power consumption < 30 mW, and an instability (Allan deviation) < 1x10^-11 during a 1-hour averaging interval. This paper describes the VCSEL requirements for CPT-based atomic clocks, which include single mode operation, single polarization operation, modulation bandwidth > 4 GHz, low power consumption (for the CSAC), narrow linewidth, and low relative intensity noise (RIN). A significant manufacturing challenge is to reproducibly obtain the required wavelength at the specified VCSEL operating temperature and drive current. Data are presented that show the advantage of operating at the D1 (rather than D2) resonance of the alkali atoms. Measurements of VCSEL linewidth will be discussed in particular, since atomic clock performance is especially sensitive to this parameter.

  7. Atomic and gravitational clocks

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Goldman, I.

    1982-01-01

    Atomic and gravitational clocks are governed by the laws of electrodynamics and gravity, respectively. While the strong equivalence principle (SEP) assumes that the two clocks have been synchronous at all times, recent planetary data seem to suggest a possible violation of the SEP. Past analysis of the implications of an SEP violation on different physical phenomena revealed no disagreement. However, these studies assumed that the two different clocks can be consistently constructed within the framework. The concept of scale invariance, and the physical meaning of different systems of units, are now reviewed and the construction of two clocks that do not remain synchronous - whose rates are related by a non-constant function beta sub a - is demonstrated. The cosmological character of beta sub a is also discussed.

  8. Optical atomic clocks

    NASA Astrophysics Data System (ADS)

    Poli, N.; Oates, C. W.; Gill, P.; Tino, G. M.

    2013-12-01

    In the last ten years extraordinary results in time and frequency metrology have been demonstrated. Frequency-stabilization techniques for continuous-wave lasers and femtosecond optical frequency combs have enabled a rapid development of frequency standards based on optical transitions in ultra-cold neutral atoms and trapped ions. As a result, today's best performing atomic clocks tick at an optical rate and allow scientists to perform high-resolution measurements with a precision approaching a few parts in 1018. This paper reviews the history and the state of the art in optical-clock research and addresses the implementation of optical clocks in a possible future redefinition of the SI second as well as in tests of fundamental physics.

  9. VLBI clock synchronization. [for atomic clock rate

    NASA Technical Reports Server (NTRS)

    Counselman, C. C., III; Shapiro, I. I.; Rogers, A. E. E.; Hinteregger, H. F.; Knight, C. A.; Whitney, A. R.; Clark, T. A.

    1977-01-01

    The potential accuracy of VLBI (very long baseline interferometry) for clock epoch and rate comparisons was demonstrated by results from long- and short-baseline experiments. It was found that atomic clocks at widely separated sites (several thousand kilometers apart) can be synchronized to within several nanoseconds from a few minutes of VLBI observations and to within one nanosecond from several hours of observations.

  10. Primary Atomic Clock Reference System

    NASA Technical Reports Server (NTRS)

    2001-01-01

    An artist's concept of the Primary Atomic Clock Reference System (PARCS) plarned to fly on the International Space Station (ISS). PARCS will make even more accurate atomic time available to everyone, from physicists testing Einstein's Theory of Relativity, to hikers using the Global Positioning System to find their way. In ground-based atomic clocks, lasers are used to cool and nearly stop atoms of cesium whose vibrations are used as the time base. The microgravity of space will allow the atoms to be suspended in the clock rather than circulated in an atomic fountain, as required on Earth. PARCS is being developed by the Jet Propulsion Laboratory with principal investigators at the National Institutes of Standards and Technology and the University of Colorado, Boulder. See also No. 0103191

  11. Primary Atomic Clock Reference System

    NASA Technical Reports Server (NTRS)

    2001-01-01

    An artist's concept of the Primary Atomic Clock Reference System (PARCS) plarned to fly on the International Space Station (ISS). PARCS will make even more accurate atomic time available to everyone, from physicists testing Einstein's Theory of Relativity, to hikers using the Global Positioning System to find their way. In ground-based atomic clocks, lasers are used to cool and nearly stop atoms of cesium whose vibrations are used as the time base. The microgravity of space will allow the atoms to be suspended in the clock rather than circulated in an atomic fountain, as required on Earth. PARCS is being developed by the Jet Propulsion Laboratory with principal investigators at the National Institutes of Standards and Technology and the University of Colorado, Boulder. See also No. 0100120.

  12. Stochastic models for atomic clocks

    NASA Technical Reports Server (NTRS)

    Barnes, J. A.; Jones, R. H.; Tryon, P. V.; Allan, D. W.

    1983-01-01

    For the atomic clocks used in the National Bureau of Standards Time Scales, an adequate model is the superposition of white FM, random walk FM, and linear frequency drift for times longer than about one minute. The model was tested on several clocks using maximum likelihood techniques for parameter estimation and the residuals were acceptably random. Conventional diagnostics indicate that additional model elements contribute no significant improvement to the model even at the expense of the added model complexity.

  13. Next Generation JPL Ultra-Stable Trapped Ion Atomic Clocks

    NASA Technical Reports Server (NTRS)

    Burt, Eric; Tucker, Blake; Larsen, Kameron; Hamell, Robert; Tjoelker, Robert

    2013-01-01

    Over the past decade, trapped ion atomic clock development at the Jet Propulsion Laboratory (JPL) has focused on two directions: 1) new atomic clock technology for space flight applications that require strict adherence to size, weight, and power requirements, and 2) ultra-stable atomic clocks, usually for terrestrial applications emphasizing ultimate performance. In this paper we present a new ultra-stable trapped ion clock designed, built, and tested in the second category. The first new standard, L10, will be delivered to the Naval Research Laboratory for use in characterizing DoD space clocks.

  14. Shielding of longitudinal magnetic fields with thin, closely, spaced concentric cylindrical shells with applications to atomic clocks

    NASA Technical Reports Server (NTRS)

    Wolf, S. A.; Gubser, D. U.; Cox, J. E.

    1978-01-01

    A general formula is given for the longitudinal shielding effectiveness of N closed concentric cylinders. The use of these equations is demonstrated by application to the design of magnetic shields for hydrogen maser atomic clocks. Examples of design tradeoffs such as size, weight, and material thickness are discussed. Experimental results on three sets of shields fabricated by three manufacturers are presented. Two of the sets were designed employing the techniques described. Agreement between the experimental results and the design calculations is then demonstrated.

  15. Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications

    PubMed Central

    Saeedi, K.; Szech, M.; Dluhy, P.; Salvail, J.Z.; Morse, K.J.; Riemann, H.; Abrosimov, N.V.; Nötzel, N.; Litvinenko, K.L.; Murdin, B.N.; Thewalt, M.L.W.

    2015-01-01

    The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched 28Si. PMID:25990870

  16. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications

    PubMed Central

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-01-01

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm. PMID:26365754

  17. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications.

    PubMed

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-01-01

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm. PMID:26365754

  18. Laser light routing in an elongated micromachined vapor cell with diffraction gratings for atomic clock applications

    NASA Astrophysics Data System (ADS)

    Chutani, Ravinder; Maurice, Vincent; Passilly, Nicolas; Gorecki, Christophe; Boudot, Rodolphe; Abdel Hafiz, Moustafa; Abbé, Philippe; Galliou, Serge; Rauch, Jean-Yves; de Clercq, Emeric

    2015-09-01

    This paper reports on an original architecture of microfabricated alkali vapor cell designed for miniature atomic clocks. The cell combines diffraction gratings with anisotropically etched single-crystalline silicon sidewalls to route a normally-incident beam in a cavity oriented along the substrate plane. Gratings have been specifically designed to diffract circularly polarized light in the first order, the latter having an angle of diffraction matching the (111) sidewalls orientation. Then, the length of the cavity where light interacts with alkali atoms can be extended. We demonstrate that a longer cell allows to reduce the beam diameter, while preserving the clock performances. As the cavity depth and the beam diameter are reduced, collimation can be performed in a tighter space. This solution relaxes the constraints on the device packaging and is suitable for wafer-level assembly. Several cells have been fabricated and characterized in a clock setup using coherent population trapping spectroscopy. The measured signals exhibit null power linewidths down to 2.23 kHz and high transmission contrasts up to 17%. A high contrast-to-linewidth ratio is found at a linewidth of 4.17 kHz and a contrast of 5.2% in a 7-mm-long cell despite a beam diameter reduced to 600 μm.

  19. Orientation-Dependent Entanglement Lifetime in a Squeezed Atomic Clock

    SciTech Connect

    Leroux, Ian D.; Schleier-Smith, Monika H.; Vuletic, Vladan

    2010-06-25

    We study experimentally the application of a class of entangled states, squeezed spin states, to the improvement of atomic-clock precision. In the presence of anisotropic noise, the entanglement lifetime is strongly dependent on squeezing orientation. We measure the Allan deviation spectrum of a clock operated with a phase-squeezed input state. For averaging times up to 50 s the squeezed clock achieves a given precision 2.8(3) times faster than a clock operating at the standard quantum limit.

  20. Mitigating aliasing in atomic clocks

    NASA Astrophysics Data System (ADS)

    Uys, Hermann; Akhalwaya, Ismail; Sastrawan, Jarrah; Biercuk, Michael

    2015-05-01

    Passive atomic clocks periodically calibrate a classical local oscillator against an atomic quantum reference through feedback. The periodic nature of this correction leads to undesirable aliasing noise. The Dick Effect, is a special case of aliasing noise consisting of the down-conversion of clock noise at harmonics of the correction frequency to a frequency of zero. To combat the Dick effect and aliasing noise in general, we suggest an extension to the usual feedback protocol, in which we incorporate information from multiple past measurements into the correction after the most recent measurement, approximating a crude low pass anti-aliasing filter of the noise. An analytical frequency domain analysis of the approach is presented and supported by numerical time domain simulations.

  1. Atomic clocks for astrophysical measurements

    NASA Technical Reports Server (NTRS)

    Vessot, R. F. C.; Mattison, E. M.

    1982-01-01

    It is noted that recently developed atomic hydrogen masers have achieved stability well into the 10 to the -16th domain for averaging time intervals beyond 1000 sec and that further improvements are in prospect. These devices are highly adaptable for space use in very high precision measurements of angle through Very Long Baseline Interferometry (VLBI) and of range and range-rate through Doppler techniques. Space missions that will use these clocks for measuring the sun's gravity field distribution and for testing gravitation and relativity (a project that will include a search for pulsed low-frequency gravitational waves) are discussed. Estimates are made of system performance capability, and the accuracy capability of relativistic measurements is evaluated in terms of the results from the 1976 NASA/SAO spaceborne clock test of the Einstein Equivalence Principle.

  2. Improved spacecraft radio science using an on-board atomic clock: Application to gravitational wave searches

    SciTech Connect

    Tinto, Massimo; Dick, George J.; Prestage, John D.; Armstrong, J. W.

    2009-05-15

    Recent advances in space-qualified atomic clocks (low-mass, low power-consumption, frequency stability comparable to that of ground-based clocks) can enable interplanetary spacecraft radio science experiments at unprecedented Doppler sensitivities. The addition of an on-board digital receiver would allow the up- and down-link Doppler frequencies to be measured separately. Such separate, high-quality measurements allow optimal data combinations that suppress the currently leading noise sources: phase scintillation noise from the Earth's atmosphere and Doppler noise caused by mechanical vibrations of the ground antenna. Here we provide a general expression for the optimal combination of ground and on-board Doppler data and compute the sensitivity such a system would have to low-frequency gravitational waves (GWs). Assuming a plasma scintillation noise calibration comparable to that already demonstrated with the multilink CASSINI radio system, the space-clock/digital-receiver instrumentation enhancements would give GW strain sensitivity of 3.7x10{sup -14} Hz{sup -1/2} for randomly polarized, monochromatic GW signals isotropically distributed over the celestial sphere, over a two-decade ({approx}0.0001-0.01 Hz) region of the low-frequency band. This is about an order of magnitude better than currently achieved with traditional two-way coherent Doppler experiments. The utility of optimally combining simultaneous up- and down-link observations is not limited to GW searches. The Doppler tracking technique discussed here could be performed at minimal incremental cost to improve also other radio science experiments (i.e., tests of relativistic gravity, planetary and satellite gravity field measurements, atmospheric and ring occultations) on future interplanetary missions.

  3. Collisionally induced atomic clock shifts and correlations

    SciTech Connect

    Band, Y. B.; Osherov, I.

    2011-07-15

    We develop a formalism to incorporate exchange symmetry considerations into the calculation of collisional frequency shifts for atomic clocks using a density-matrix formalism. The formalism is developed for both fermionic and bosonic atomic clocks. Numerical results for a finite-temperature {sup 87}Sr {sup 1}S{sub 0} (F=9/2) atomic clock in a magic wavelength optical lattice are presented.

  4. Analysis of a magnetically trapped atom clock

    SciTech Connect

    Kadio, D.; Band, Y. B.

    2006-11-15

    We consider optimization of a rubidium atom clock that uses magnetically trapped Bose condensed atoms in a highly elongated trap, and determine the optimal conditions for minimum Allan variance of the clock using microwave Ramsey fringe spectroscopy. Elimination of magnetic field shifts and collisional shifts are considered. The effects of spin-dipolar relaxation are addressed in the optimization of the clock. We find that for the interstate interaction strength equal to or larger than the intrastate interaction strengths, a modulational instability results in phase separation and symmetry breaking of the two-component condensate composed of the ground and excited hyperfine clock levels, and this mechanism limits the clock accuracy.

  5. Hunting for topological dark matter with atomic clocks

    NASA Astrophysics Data System (ADS)

    Derevianko, A.; Pospelov, M.

    2014-12-01

    The cosmological applications of atomic clocks so far have been limited to searches for the uniform-in-time drift of fundamental constants. We point out that a transient-in-time change of fundamental constants can be induced by dark-matter objects that have large spatial extent, such as stable topological defects built from light non-Standard Model fields. Networks of correlated atomic clocks, some of them already in existence, such as the Global Positioning System, can be used as a powerful tool to search for topological defect dark matter, thus providing another important fundamental physics application for the ever-improving accuracy of atomic clocks. During the encounter with an extended dark-matter object, as it sweeps through the network, initially synchronized clocks will become desynchronized. Time discrepancies between spatially separated clocks are expected to exhibit a distinct signature, encoding the defect's space structure and its interaction strength with atoms.

  6. Compact, Highly Stable Ion Atomic Clock

    NASA Technical Reports Server (NTRS)

    Prestage, John

    2008-01-01

    A mercury-ion clock now at the breadboard stage of development (see figure) has a stability comparable to that of a hydrogen-maser clock: In tests, the clock exhibited an Allan deviation of between 2 x 10(exp -13) and 3 x 10(exp -13) at a measurement time of 1 second, averaging to about 10(exp -15) at 1 day. However, the clock occupies a volume of only about 2 liters . about a hundredth of the volume of a hydrogen-maser clock. The ion-handling parts of the apparatus are housed in a sealed vacuum tube, wherein only a getter pump is used to maintain the vacuum. Hence, this apparatus is a prototype of a generation of small, potentially portable high-precision clocks for diverse ground- and space-based navigation and radio science applications. Furthermore, this new ion-clock technology is about 100 times more stable and precise than the rubidium atomic clocks currently in use in the NAV STAR GPS Earth-orbiting satellites. In this clock, mercury ions are shuttled between a quadrupole and a 16-pole linear radio-frequency trap. In the quadrupole trap, the ions are tightly confined and optical state selection from a Hg-202 radio-frequency-discharge ultraviolet lamp is carried out. In the 16-pole trap, the ions are more loosely confined and atomic transitions resonant at frequency of about 40.507 GHz are interrogated by use of a microwave beam at that frequency. The trapping of ions effectively eliminates the frequency pulling caused by wall collisions inherent to gas-cell clocks. The shuttling of the ions between the two traps enables separation of the state-selection process from the clock microwave- resonance process, so that each of these processes can be optimized independently of the other. The basic ion-shuttling, two-trap scheme as described thus far is not new: it has been the basis of designs of prior larger clocks. The novelty of the present development lies in major redesigns of its physics package (the ion traps and the vacuum and optical subsystems) to effect

  7. Systematic Effects in Atomic Fountain Clocks

    NASA Astrophysics Data System (ADS)

    Gibble, Kurt

    2016-06-01

    We describe recent advances in the accuracies of atomic fountain clocks. New rigorous treatments of the previously large systematic uncertainties, distributed cavity phase, microwave lensing, and background gas collisions, enabled these advances. We also discuss background gas collisions of optical lattice and ion clocks and derive the smooth transition of the microwave lensing frequency shift to photon recoil shifts for large atomic wave packets.

  8. An atomic clock with 10(-18) instability.

    PubMed

    Hinkley, N; Sherman, J A; Phillips, N B; Schioppo, M; Lemke, N D; Beloy, K; Pizzocaro, M; Oates, C W; Ludlow, A D

    2013-09-13

    Atomic clocks have been instrumental in science and technology, leading to innovations such as global positioning, advanced communications, and tests of fundamental constant variation. Timekeeping precision at 1 part in 10(18) enables new timing applications in relativistic geodesy, enhanced Earth- and space-based navigation and telescopy, and new tests of physics beyond the standard model. Here, we describe the development and operation of two optical lattice clocks, both using spin-polarized, ultracold atomic ytterbium. A measurement comparing these systems demonstrates an unprecedented atomic clock instability of 1.6 × 10(-18) after only 7 hours of averaging. PMID:23970562

  9. Precise time dissemination via portable atomic clocks

    NASA Technical Reports Server (NTRS)

    Putkovich, K.

    1982-01-01

    The most precise operational method of time dissemination over long distances presently available to the Precise Time and Time Interval (PTTI) community of users is by means of portable atomic clocks. The Global Positioning System (GPS), the latest system showing promise of replacing portable clocks for global PTTI dissemination, was evaluated. Although GPS has the technical capability of providing superior world-wide dissemination, the question of present cost and future accessibility may require a continued reliance on portable clocks for a number of years. For these reasons a study of portable clock operations as they are carried out today was made. The portable clock system that was utilized by the U.S. Naval Observatory (NAVOBSY) in the global synchronization of clocks over the past 17 years is described and the concepts on which it is based are explained. Some of its capabilities and limitations are also discussed.

  10. Deep Space Atomic Clock Ticks Toward Success

    NASA Video Gallery

    Dr. Todd Ely, principal investigator for NASA's Deep Space Atomic Clock at the Jet Propulsion Laboratory in Pasadena, Calif., spotlights the paradigm-busting innovations now in development to revol...

  11. Atomic Clock Based On Linear Ion Trap

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Dick, G. John

    1992-01-01

    Highly stable atomic clock based on excitation and measurement of hyperfine transition in 199Hg+ ions confined in linear quadrupole trap by radio-frequency and static electric fields. Configuration increases stability of clock by enabling use of enough ions to obtain adequate signal while reducing non-thermal component of motion of ions in trapping field, reducing second-order Doppler shift of hyperfine transition. Features described in NPO-17758 "Linear Ion Trap for Atomic Clock." Frequency standard based on hyperfine transition described in NPO-17456, "Trapped-Mercury-Ion Frequency Standard."

  12. Tests of Lorentz invariance with atomic clocks

    NASA Astrophysics Data System (ADS)

    Mohan, Lakshmi

    Lorentz invariance has been the cornerstone of special relativity. Recent theories have been proposed which suggest violations of Lorentz invariance. Experiments have been conducted using clocks that place the strictest limits on these theories. The thesis focuses on the Mansouri and Sexl formulation and I calculate using this framework the Doppler effect, Compton effect, Maxwell's equations, Hydrogen energy levels and other effects. I conclude the thesis by suggesting a possible method of testing my results using atomic clocks.

  13. Ion-Atom Cold Collisions and Atomic Clocks

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Maleki, Lute; Tjoelker, Robert L.

    1997-01-01

    Collisions between ultracold neutral atoms have for some time been the subject of investigation, initially with hydrogen and more recently with laser cooled alkali atoms. Advances in laser cooling and trapping of neutral atoms in a Magneto-Optic Trap (MOT) have made cold atoms available as the starting point for many laser cooled atomic physics investigations. The most spectacularly successful of these, the observation of Bose-Einstein Condensation (BEC) in a dilute ultra-cold spin polarized atomic vapor, has accelerated the study of cold collisions. Experimental and theoretical studies of BEC and the long range interaction between cold alkali atoms is at the boundary of atomic and low temperature physics. Such studies have been difficult and would not have been possible without the development and advancement of laser cooling and trapping of neutral atoms. By contrast, ion-atom interactions at low temperature, also very difficult to study prior to modern day laser cooling, have remained largely unexplored. But now, many laboratories worldwide have almost routine access to cold neutral atoms. The combined technologies of ion trapping, together with laser cooling of neutrals has made these studies experimentally feasible and several very important, novel applications might come out of such investigations . This paper is an investigation of ion-atom interactions in the cold and ultra-cold temperature regime. Some of the collisional ion-atom interactions present at room temperature are very much reduced in the low temperature regime. Reaction rates for charge transfer between unlike atoms, A + B(+) approaches A(+) + B, are expected to fall rapidly with temperature, approximately as T(sup 5/2). Thus, cold mixtures of atoms and ions are expected to coexist for very long times, unlike room temperature mixtures of the same ion-atom combination. Thus, it seems feasible to cool ions via collisions with laser cooled atoms. Many of the conventional collisional interactions

  14. Sagnac Interferometry with a Single Atomic Clock.

    PubMed

    Stevenson, R; Hush, M R; Bishop, T; Lesanovsky, I; Fernholz, T

    2015-10-16

    The Sagnac effect enables interferometric measurements of rotation with high precision. Using matter waves instead of light promises resolution enhancement by orders of magnitude that scales with particle mass. So far, the paradigm for matter wave Sagnac interferometry relies on de Broglie waves and thus on free propagation of atoms either in free fall or within waveguides. However, the Sagnac effect can be expressed as a proper time difference experienced by two observers moving in opposite directions along closed paths and has indeed been measured with atomic clocks flown around Earth. Inspired by this, we investigate an interferometer comprised of a single atomic clock. The Sagnac effect manifests as a phase shift between trapped atoms in different internal states after transportation along closed paths in opposite directions, without any free propagation. With analytic models, we quantify limitations of the scheme arising from atomic dynamics and finite temperature. Furthermore, we suggest an implementation with previously demonstrated technology. PMID:26550871

  15. Sagnac Interferometry with a Single Atomic Clock

    NASA Astrophysics Data System (ADS)

    Stevenson, R.; Hush, M. R.; Bishop, T.; Lesanovsky, I.; Fernholz, T.

    2015-10-01

    The Sagnac effect enables interferometric measurements of rotation with high precision. Using matter waves instead of light promises resolution enhancement by orders of magnitude that scales with particle mass. So far, the paradigm for matter wave Sagnac interferometry relies on de Broglie waves and thus on free propagation of atoms either in free fall or within waveguides. However, the Sagnac effect can be expressed as a proper time difference experienced by two observers moving in opposite directions along closed paths and has indeed been measured with atomic clocks flown around Earth. Inspired by this, we investigate an interferometer comprised of a single atomic clock. The Sagnac effect manifests as a phase shift between trapped atoms in different internal states after transportation along closed paths in opposite directions, without any free propagation. With analytic models, we quantify limitations of the scheme arising from atomic dynamics and finite temperature. Furthermore, we suggest an implementation with previously demonstrated technology.

  16. The Deep Space Atomic Clock Mission

    NASA Technical Reports Server (NTRS)

    Ely, Todd A.; Koch, Timothy; Kuang, Da; Lee, Karen; Murphy, David; Prestage, John; Tjoelker, Robert; Seubert, Jill

    2012-01-01

    The Deep Space Atomic Clock (DSAC) mission will demonstrate the space flight performance of a small, low-mass, high-stability mercury-ion atomic clock with long term stability and accuracy on par with that of the Deep Space Network. The timing stability introduced by DSAC allows for a 1-Way radiometric tracking paradigm for deep space navigation, with benefits including increased tracking via utilization of the DSN's Multiple Spacecraft Per Aperture (MSPA) capability and full ground station-spacecraft view periods, more accurate radio occultation signals, decreased single-frequency measurement noise, and the possibility for fully autonomous on-board navigation. Specific examples of navigation and radio science benefits to deep space missions are highlighted through simulations of Mars orbiter and Europa flyby missions. Additionally, this paper provides an overview of the mercury-ion trap technology behind DSAC, details of and options for the upcoming 2015/2016 space demonstration, and expected on-orbit clock performance.

  17. Mapping Out Atom-Wall Interaction with Atomic Clocks

    SciTech Connect

    Derevianko, A.; Obreshkov, B.; Dzuba, V. A.

    2009-09-25

    We explore the feasibility of probing atom-wall interaction with atomic clocks based on atoms trapped in engineered optical lattices. Optical lattice is normal to the wall. By monitoring the wall-induced clock shift at individual wells of the lattice, one would measure the dependence of the atom-wall interaction on the atom-wall separation. We find that the induced clock shifts are large and observable at already experimentally demonstrated levels of accuracy. We show that this scheme may uniquely probe the long-range atom-wall interaction in all three qualitatively distinct regimes of the interaction: van der Waals (image-charge interaction), Casimir-Polder (QED vacuum fluctuations), and Lifshitz (thermal-bath fluctuations) regimes.

  18. Blackbody radiation shifts in optical atomic clocks.

    PubMed

    Safronova, Marianna; Kozlov, Mikhail; Clark, Charles

    2012-03-01

    A review of recent theoretical calculations of blackbody radiation (BBR) shifts in optical atomic clocks is presented. We summarize previous results for monovalent ions that were obtained by a relativistic all-order single-double method, where all single and double excitations of the Dirac- Fock wave function are included to all orders of perturbation theory. A recently developed method for accurate calculations of BBR shifts in divalent atoms is then presented. This approach combines the relativistic all-order method and the configuration interaction method, which provides for accurate treatment of correlation corrections in atoms with two valence electrons. Calculations of the BBR shifts in B+, Al+, and In+ have enabled us to reduce the present fractional uncertainties in the frequencies of their clock transitions as measured at room temperature: to 4 × 10-19 for Al+ and 10-18 for B+ and In+. These uncertainties approach recent estimates of the limits of precision of currently proposed optical atomic clocks. We discuss directions of future theoretical developments for reducing clock uncertainties resulting from blackbody radiation shifts. PMID:22481777

  19. Compact microwave cavity for hydrogen atomic clock

    NASA Technical Reports Server (NTRS)

    Zhang, Dejun; Zhang, Yan; Fu, Yigen; Zhang, Yanjun

    1992-01-01

    A summary is presented that introduces the compact microwave cavity used in the hydrogen atomic clock. Special emphasis is placed on derivation of theoretical calculating equations of main parameters of the microwave cavity. A brief description is given of several methods for discriminating the oscillating modes. Experimental data and respective calculated values are also presented.

  20. Efficient atomic clocks operated with several atomic ensembles.

    PubMed

    Borregaard, J; Sørensen, A S

    2013-08-30

    Atomic clocks are typically operated by locking a local oscillator (LO) to a single atomic ensemble. In this Letter, we propose a scheme where the LO is locked to several atomic ensembles instead of one. This results in an exponential improvement compared to the conventional method and provides a stability of the clock scaling as (αN)(-m/2) with N being the number of atoms in each of the m ensembles and α a constant depending on the protocol being used to lock the LO. PMID:24033017

  1. Zero-dead-time operation of interleaved atomic clocks.

    PubMed

    Biedermann, G W; Takase, K; Wu, X; Deslauriers, L; Roy, S; Kasevich, M A

    2013-10-25

    We demonstrate a zero-dead-time operation of atomic clocks. This clock reduces sensitivity to local oscillator noise, integrating as nearly 1/τ whereas a clock with dead time integrates as 1/τ(1/2) under identical conditions. We contend that a similar scheme may be applied to improve the stability of optical clocks. PMID:24206471

  2. Relativistic general-order coupled-cluster method for high-precision calculations: Application to the Al{sup +} atomic clock

    SciTech Connect

    Kallay, Mihaly; Nataraj, H. S.; Sahoo, B. K.; Das, B. P.; Visscher, Lucas

    2011-03-15

    We report the implementation of a general-order relativistic coupled-cluster method for performing high-precision calculations of atomic and molecular properties. As a first application, the black-body radiation shift of the Al{sup +} clock has been estimated precisely. The computed shift relative to the frequency of the 3s{sup 2} {sup 1}S{sub 0}{sup e}{yields}3s3p {sup 3}P{sub 0}{sup o} clock transition given by (-3.66{+-}0.60)x10{sup -18} calls for an improvement over the recent measurement with a reported result of (-9{+-}3)x10{sup -18}[Phys. Rev. Lett. 104, 070802 (2010)].

  3. Laser Cooled Atomic Clocks in Space

    NASA Technical Reports Server (NTRS)

    Thompson, R. J.; Kohel, J.; Klipstein, W. M.; Seidel, D. J.; Maleki, L.

    2000-01-01

    The goals of the Glovebox Laser-cooled Atomic Clock Experiment (GLACE) are: (1) first utilization of tunable, frequency-stabilized lasers in space, (2) demonstrate laser cooling and trapping in microgravity, (3) demonstrate longest 'perturbation-free' interaction time for a precision measurement on neutral atoms, (4) Resolve Ramsey fringes 2-10 times narrower than achievable on Earth. The approach taken is: the use of COTS components, and the utilization of prototype hardware from LCAP flight definition experiments. The launch date is scheduled for Oct. 2002. The Microgravity Science Glovebox (MSG) specifications are reviewed, and a picture of the MSG is shown.

  4. Atomic clock using coherent population trapping in a cesium cell: frequency stability and limitations

    NASA Astrophysics Data System (ADS)

    Mejri, Sinda; Tricot, Francois; Danet, Jean-Marie; Yun, Peter; De Clercq, Emeric; Guerandel, Stephane

    2016-06-01

    Toward the next generation of compact devices, atomic clocks based on coherent population trapping (CPT) offer a very interesting alternative. We present a review of our studies on the short and mid term stability of a compact high performance atomic clock based on CPT in view of portable applications.

  5. Atomic clock augmentation for receivers using the Global Positioning System

    NASA Astrophysics Data System (ADS)

    Kline, Paul Andrew

    For receivers using the Global Positioning System (GPS), it is standard procedure to treat the receiver clock bias from GPS time as an unknown. This requires four range measurements to the satellites in order to solve for three dimensional position and clock offset. If the receiver clock could be synchronized with GPS time, the extra range measurement would not be necessary. To achieve this synchronization, a stable frequency reference must be incorporated into the GPS user set. This concept is known as clock aiding or clock augmentation of GPS receivers. Clock augmentation increases the availability of the navigation function because only three GPS satellites are required. Also, it is shown that clock augmentation improves vertical accuracy by reducing the vertical dilution of precision (VDOP), which is a unitless multiplier that translates range measurement error into vertical position error. This improvement in vertical accuracy is particularly beneficial for applications involving final approach and landing of aircraft using GPS, because GPS typically provides better horizontal accuracy than vertical accuracy. The benefits of atomic clock augmentation are limited by factors that cause a loss of synchronization either between the receiver and GPS time, or between ground station and airborne receivers processing GPS data in differential mode (DGPS). Among the error sources that cause a clock offset are antenna rotation, hardware drifts due to temperature variations, and relativistic effects for GPS receivers on moving platforms. Antenna rotation and temperature effects are addressed and supported by experimental data. It is shown that two particular relativity terms thought to be missing from GPS receiver algorithms are not evident in data collected during a flight test experiment. Upon addressing the error sources, the dissertation concludes with analysis of DGPS data collected during a flight test at the Federal Aviation Administration (FAA) Tech Center in

  6. VCSEL polarization control for chip-scale atomic clocks.

    SciTech Connect

    Geib, Kent Martin; Peake, Gregory Merwin; Wendt, Joel Robert; Serkland, Darwin Keith; Keeler, Gordon Arthur

    2007-01-01

    Sandia National Laboratories and Mytek, LLC have collaborated to develop a monolithically-integrated vertical-cavity surface-emitting laser (VCSEL) assembly with controllable polarization states suitable for use in chip-scale atomic clocks. During the course of this work, a robust technique to provide polarization control was modeled and demonstrated. The technique uses deeply-etched surface gratings oriented at several different rotational angles to provide VCSEL polarization stability. A rigorous coupled-wave analysis (RCWA) model was used to optimize the design for high polarization selectivity and fabrication tolerance. The new approach to VCSEL polarization control may be useful in a number of defense and commercial applications, including chip-scale atomic clocks and other low-power atomic sensors.

  7. The Saga of Light-Matter Interaction and Magneto-optical Effects Applications to Atomic Magnetometry, Laser-cooled Atoms, Atomic Clocks, Geomagnetism, and Plant Bio-magnetism

    NASA Astrophysics Data System (ADS)

    Corsini, Eric P.

    The quest to expand the limited sensorial domain, in particular to bridge the inability to gauge magnetic fields near and far, has driven the fabrication of remedial tools. The interaction of ferromagnetic material with a magnetic field had been the only available technique to gauge that field for several millennium. The advent of electricity and associated classical phenomena captured in the four Maxwell equations, were a step forward. In the early 1900s, the model of quantum mechanics provided a two-way leap forward. One came from the newly understood interaction of light and matter, and more specifically the three-way coupling of photons, atoms' angular momenta, and magnetic field, which are the foundations of atomic magnetometry. The other came from magnetically sensitive quantum effects in a fabricated energy-ladder form of matter cooled to a temperature below that of the energy steps; these quantum effects gave rise to the superconducting quantum interference device (SQUID). Research using atomic magnetometers and SQUIDs has resulted in thousands of publications, text books, and conferences. The current status in each field is well described in Refs. [48,49,38,42] and all references therein. In this work we develop and investigate techniques and applications pertaining to atomic magnetometry. [Full text: eric.corsini gmail.com].

  8. Intense, Narrow Atomic-Clock Resonances

    NASA Astrophysics Data System (ADS)

    Jau, Y.-Y.; Post, A. B.; Kuzma, N. N.; Braun, A. M.; Romalis, M. V.; Happer, W.

    2004-03-01

    We present experimental and theoretical results showing that magnetic resonance transitions from the “end” sublevels of maximum or minimum spin in alkali-metal vapors are a promising alternative to the conventional 0-0 transition for small-size gas-cell atomic clocks. For these “end resonances,” collisional spin-exchange broadening, which often dominates the linewidth of the 0-0 resonance, decreases with increasing spin polarization and vanishes for 100% polarization. The end resonances also have much stronger signals than the 0-0 resonance, and are readily detectable in cells with high buffer-gas pressure.

  9. The dynamic Allan Variance IV: characterization of atomic clock anomalies.

    PubMed

    Galleani, Lorenzo; Tavella, Patrizia

    2015-05-01

    The number of applications where precise clocks play a key role is steadily increasing, satellite navigation being the main example. Precise clock anomalies are hence critical events, and their characterization is a fundamental problem. When an anomaly occurs, the clock stability changes with time, and this variation can be characterized with the dynamic Allan variance (DAVAR). We obtain the DAVAR for a series of common clock anomalies, namely, a sinusoidal term, a phase jump, a frequency jump, and a sudden change in the clock noise variance. These anomalies are particularly common in space clocks. Our analytic results clarify how the clock stability changes during these anomalies. PMID:25965674

  10. The chip-scale atomic clock : prototype evaluation.

    SciTech Connect

    Mescher, Mark; Varghese, Mathew; Lutwak, Robert; Serkland, Darwin Keith; Tepolt, Gary; Geib, Kent Martin; Leblanc, John; Peake, Gregory Merwin; Rashid, Ahmed

    2007-12-01

    The authors have developed a chip-scale atomic clock (CSAC) for applications requiring atomic timing accuracy in portable battery-powered applications. At PTTI/FCS 2005, they reported on the demonstration of a prototype CSAC, with an overall size of 10 cm{sup 3}, power consumption > 150 mW, and short-term stability sy(t) < 1 x 10-9t-1/2. Since that report, they have completed the development of the CSAC, including provision for autonomous lock acquisition and a calibrated output at 10.0 MHz, in addition to modifications to the physics package and system architecture to improve performance and manufacturability.

  11. Development of a compact cold-atom atomic clock based on coherent population trapping

    NASA Astrophysics Data System (ADS)

    Blanshan, Eric M.

    Field-grade atomic clocks capable of primary standard performance in compact physics packages would be of significant value in a variety of applications ranging from network synchronization and secure communications to GPS hold-over and inertial navigation. A cold-atom coherent population trapping (CACPT) clock featuring laser-cooled atoms and pulsed Ramsey interrogation is a strong candidate for this technology if the principal frequency shifts can be controlled and the performance degradation associated with miniaturization can be overcome. In this thesis, research focused on the development of this type of compact atomic clock is presented. To address the low atom numbers obtained in small cold-atom sources, experiments were performed in which an atomic beam was decelerated with bichromatic stimulated laser forces and loaded into a mm-scale magneto-optical trap, increasing the atom number by a factor of 12.5. A CACPT clock using the high-contrast lin||lin optical interrogation technique was developed and achieved a stability of 7 x 10-13 after one hour of integration. Doppler shifts in the clock are explained using a simple kinematic model and canceled by interrogating the atoms with a counter-propagating CPT configuration. Finally, a thorough characterization of the AC-stark effect in lin||lin CPT was performed. Observed shifts are explained in terms of contributions from coherent CPT-generating couplings and population transfer effects caused by optical pumping from incoherent light. Measurements are compared with existing and new theoretical treatments, and a laser configuration is identified that reduces clock drift from light shifts to less than 10-14 for the current system.

  12. A (201)Hg+ Comagnetometer for (199)Hg+ Trapped Ion Space Atomic Clocks

    NASA Technical Reports Server (NTRS)

    Burt, Eric A.; Taghavi, Shervin; Tjoelker, Robert L.

    2011-01-01

    A method has been developed for unambiguously measuring the exact magnetic field experienced by trapped mercury ions contained within an atomic clock intended for space applications. In general, atomic clocks are insensitive to external perturbations that would change the frequency at which the clocks operate. On a space platform, these perturbative effects can be much larger than they would be on the ground, especially in dealing with the magnetic field environment. The solution is to use a different isotope of mercury held within the same trap as the clock isotope. The magnetic field can be very accurately measured with a magnetic-field-sensitive atomic transition in the added isotope. Further, this measurement can be made simultaneously with normal clock operation, thereby not degrading clock performance. Instead of using a conventional magnetometer to measure ambient fields, which would necessarily be placed some distance away from the clock atoms, first order field-sensitive atomic transition frequency changes in the atoms themselves determine the variations in the magnetic field. As a result, all ambiguity over the exact field value experienced by the atoms is removed. Atoms used in atomic clocks always have an atomic transition (often referred to as the clock transition) that is sensitive to magnetic fields only in second order, and usually have one or more transitions that are first-order field sensitive. For operating parameters used in the (199)Hg(+) clock, the latter can be five orders of magnitude or more sensitive to field fluctuations than the clock transition, thereby providing an unambiguous probe of the magnetic field strength.

  13. The Sr optical lattice clock at JILA: A new record in atomic clock performance

    NASA Astrophysics Data System (ADS)

    Nicholson, Travis; Bloom, Benjamin; Williams, Jason; Campbell, Sara; Bishof, Michael; Zhang, Xibo; Zhang, Wei; Bromley, Sarah; Hutson, Ross; McNally, Rees; Ye, Jun

    2014-05-01

    The exquisite control exhibited over quantum states of individual particles has revolutionized the field of precision measurement, as exemplified by highly accurate atomic clocks. Optical clocks have been the most accurate frequency standards for the better part of a decade, surpassing even the cesium microwave fountains upon which the SI second is based. Two classes of optical clocks have outperformed cesium: single-ion clocks and optical lattice clocks. Historically ion clocks have always been more accurate, and the precision of ion clocks and lattice clocks has been comparable. For years it has been unclear if lattice clocks can overcome key systematics and become more accurate than ion clocks. In this presentation I report the first lattice clock that has surpassed ion clocks in both precision and accuracy. These measurements represent a tenfold improvement in precision and a factor of 20 improvement in accuracy over the previous best lattice clock results. This work paves the way for a better realization of SI units, the development of more sophisticated quantum sensors, and precision tests of the fundamental laws of nature.

  14. Stable 85Rb micro vapour cells: fabrication based on anodic bonding and application in chip-scale atomic clocks

    NASA Astrophysics Data System (ADS)

    Su, Juan; Deng, Ke; Guo, Deng-Zhu; Wang, Zhong; Chen, Jing; Zhang, Geng-Min; Chen, Xu-Zong

    2010-11-01

    We describe the microfabrication of 85Rb vapour cells using a glass-silicon anodic bonding technique and in situ chemical reaction between rubidium chloride and barium azide to produce Rb. Under controlled conditions, the pure metallic Rb drops and buffer gases were obtained in the cells with a few mm3 internal volumes during the cell sealing process. At an ambient temperature of 90 °C the optical absorption resonance of 85Rb D1 transition with proper broadening and the corresponding coherent population trapping (CPT) resonance, with a signal contrast of 1.5% and linewidth of about 1.7 kHz, have been detected. The sealing quality and the stability of the cells have also been demonstrated experimentally by using the helium leaking detection and the after-9-month optoelectronics measurement which shows a similar CPT signal as its original status. In addition, the physics package of chip-scale atomic clock (CSAC) based on the cell was realized. The measured frequency stability of the physics package can reach to 2.1 × 10-10 at one second when the cell was heated to 100 °C which proved that the cell has the quality to be used in portable and battery-operated devices.

  15. Using Clocks and Atomic Interferometry for Gravity Field Observations

    NASA Astrophysics Data System (ADS)

    Müller, Jürgen

    2016-07-01

    New technology developed in the frame of fundamental physics may lead to enhanced capabilities for geodetic applications such as refined observations of the Earth's gravity field. Here, we will present new sensor measurement concepts that apply atomic interferometry for gravimetry and clock measurements for observing potential values. In the first case, gravity anomalies can be determined by observing free-falling atoms (quantum gravimetry). In the second case, highly precise optical clocks can be used to measure differences of the gravity potential over long distances (relativistic geodesy). Principally, also inter-satellite ranging between test masses in space with nanometer accuracy belongs to these novel developments. We will show, how the new measurement concepts are connected to classical geodetic concepts, e.g. geopotential numbers and clock readings. We will illustrate the application of these new methods and their benefit for geodesy, where local and global mass variations can be observed with unforeseen accuracy and resolution, mass variations that reflect processes in the Earth system. We will present a few examples where geodesy will potentially benefit from these developments. Thus, the novel technologies might be applied for defining and realizing height systems in a new way, but also for fast local gravimetric surveys and exploration.

  16. Suppressing Loss of Ions in an Atomic Clock

    NASA Technical Reports Server (NTRS)

    Prestage, John; Chung, Sang

    2010-01-01

    An improvement has been made in the design of a compact, highly stable mercury- ion clock to suppress a loss of ions as they are transferred between the quadrupole and higher multipole ion traps. Such clocks are being developed for use aboard spacecraft for navigation and planetary radio science. The modification is also applicable to ion clocks operating on Earth: indeed, the success of the modification has been demonstrated in construction and operation of a terrestrial breadboard prototype of the compact, highly stable mercury-ion clock. Selected aspects of the breadboard prototype at different stages of development were described in previous NASA Tech Briefs articles. The following background information is reviewed from previous articles: In this clock as in some prior ion clocks, mercury ions are shuttled between two ion traps, one a 16- pole linear radio-frequency trap, while the other is a quadrupole radio-frequency trap. In the quadrupole trap, ions are tightly confined and optical state selection from a 202Hg lamp is carried out. In the 16-pole trap, the ions are more loosely confined and atomic transitions are interrogated by use of a microwave beam at approximately 40.507 GHz. The trapping of ions effectively eliminates the frequency pulling that would otherwise be caused by collisions between clock atoms and the wall of a gas cell. The shuttling of the ions between the two traps enables separation of the state-selection process from the clock microwave-resonance process, so that each of these processes can be optimized independently of the other. This is similar to the operation of an atomic beam clock, except that with ions the beam can be halted and reversed as ions are shuttled back and forth between the two traps. When the two traps are driven at the same radio frequency, the strength of confinement can be reduced near the junction between the two traps, depending upon the relative phase of the RF voltage used to operate each of the two traps, and

  17. Noise suppression in coherent population-trapping atomic clock by differential magneto-optic rotation detection.

    PubMed

    Tan, Bozhong; Tian, Yuan; Lin, Huifang; Chen, Jiehua; Gu, Sihong

    2015-08-15

    We propose and investigate a scheme for differential detection of the magneto-optic rotation (MOR) effect, where a linearly polarized bichromatic laser field is coherent population-trapping (CPT)-resonant with alkali atoms, and discuss the application of this effect to CPT-based atomic clocks. The results of our study indicate that laser noise in a vertical cavity surface-emitting laser-based CPT atomic clock can be effectively suppressed by the proposed scheme. The proposed scheme promises to realize a packaged MOR-CPT atomic clock that has significantly better frequency stability coupled with similar power consumption, volume, and cost when compared with currently available packaged CPT atomic clocks. PMID:26274639

  18. Parcs:. a Laser-Cooled Atomic Clock in Space

    NASA Astrophysics Data System (ADS)

    Heavner, T. P.; Hollberg, L. W.; Jefferts, S. R.; Robinson, H. G.; Sullivan, D. B.; Walls, F. L.; Ashby, N.; Klipstein, W. M.; Maleki, L.; Seidel, D. J.; Thompson, R. J.; Wu, S.; Young, L.; Mattison, E. M.; Vessot, R. F. C.; Demarchi, A.

    2002-04-01

    This paper describes progress toward the development of a Primary Atomic Reference Clock in Space (PARCS) and reviews the scientific and technical objectives of the PARCS mission. PARCS is a collaborative effort involving the National Institute of Standards and Technology (NIST), the University of Colorado, the Jet Propulsion Laboratory (JPL), the Harvard Smithsonian Center for Astrophysics (SAO) and the Politecnico di Torino. Space systems for this experiment include a laser-cooled cesium atomic clock and a GPS frequency-comparison and orbit determination system, along with a hydrogen maser that serves as both a local oscillator for the cesium clock and a reference against which certain tests of gravitational theory can be made. In the microgravity environment of the International Space Station (ISS), cesium atoms can be launched more slowly through the clock's microwave cavity, thus significantly reducing a number of troubling effects (including several critical systematic effects), so clock performance can be substantially improved beyond that achieved on earth.

  19. Detection of atomic clock frequency jumps with the Kalman filter.

    PubMed

    Galleani, Lorenzo; Tavella, Patrizia

    2012-03-01

    Frequency jumps are common anomalies in atomic clocks aboard navigation system satellites. These anomalous behaviors must be detected quickly and accurately to minimize the impact on user positioning. We develop a detector for frequency jumps based on the Kalman filter. Numerical simulations show that the detector is fast, with high probability of detection and low probability of false alarms. It also has a low computational cost because it takes advantage of the recursive nature of the Kalman filter. Therefore, it can be used in applications in which little computational power is available, such as aboard navigation system satellites. PMID:22481785

  20. ac Stark shift of the Cs microwave atomic clock transitions

    NASA Astrophysics Data System (ADS)

    Rosenbusch, P.; Ghezali, S.; Dzuba, V. A.; Flambaum, V. V.; Beloy, K.; Derevianko, A.

    2009-01-01

    We analyze the ac Stark shift of the Cs microwave atomic clock transition theoretically and experimentally. Theoretical and experimental data are in good agreement with each other. Results indicate the absence of a magic wavelength at which there would be no differential shift of the clock states having zero projections of the total angular momentum.

  1. Limitations on long-term stability and accuracy in atomic clocks

    NASA Technical Reports Server (NTRS)

    Wineland, D. J.

    1979-01-01

    The limits to accuracy and long term stability in present atomic clocks are examined. Recent proposals for new frequency standards are discussed along with the advantages and disadvantages of frequency standards based on such ideas as laser transitions, single atoms, and atom cooling. The applicability of some of these new techniques to existing standards is examined.

  2. Apparatus for fermion atomic clock, atom interferometry and quantum pumping experiments

    NASA Astrophysics Data System (ADS)

    Ivory, M. K.; Ziltz, A.; Field, J.; Aubin, S.

    2010-03-01

    We present the current state of an apparatus designed to create and manipulate ultracold bosonic and fermionic Rb and K isotopes for a fermion atomic clock, atom interferometry, microwave trapping, and quantum pumping experiments. Quantum pumping is a phenomenon which can precisely control bias-less flow of single electrons in a circuit. Using ultracold atoms on atom chips, we can test theoretical predictions which have not yet been verified due to experimental difficulties in solid state systems. The apparatus design consists of a magneto-optical trap, magnetic transport system, atom chip, and optical dipole trap. We have demonstrated basic laser cooling and trapping and are working towards transport of the collected atoms to the atom chip for cooling to quantum degeneracy. Once quantum degeneracy is achieved at the chip, micro-magnetic reservoirs of ultracold atoms connected by a 1D ``wire'' create a circuit for various quantum pumping schemes. These schemes are also more broadly applicable to atomtronics experiments.

  3. Quantum Atomic Clock Synchronization: An Entangled Concept of Nonlocal Simultaneity

    NASA Technical Reports Server (NTRS)

    Abrams, D.; Dowling, J.; Williams, C.; Jozsa, R.

    2000-01-01

    We demonstrate that two spatially separated parties (Alice and Bob) can utilize shared prior quantum entanglement, as well as a classical information channel, to establish a synchronized pair of atomic clocks.

  4. High-stability compact atomic clock based on isotropic laser cooling

    SciTech Connect

    Esnault, Francois-Xavier; Holleville, David; Rossetto, Nicolas; Guerandel, Stephane; Dimarcq, Noel

    2010-09-15

    We present a compact cold-atom clock configuration where isotropic laser cooling, microwave interrogation, and clock signal detection are successively performed inside a spherical microwave cavity. For ground operation, a typical Ramsey fringe width of 20 Hz has been demonstrated, limited by the atom cloud's free fall in the cavity. The isotropic cooling light's disordered properties provide a large and stable number of cold atoms, leading to a high signal-to-noise ratio limited by atomic shot noise. A relative frequency stability of 2.2x10{sup -13{tau}-1/2} has been achieved, averaged down to 4x10{sup -15} after 5x10{sup 3} s of integration. Development of such a high-performance compact clock is of major relevance for on-board applications, such as satellite-positioning systems. As a cesium clock, it opens the door to a new generation of compact primary standards and timekeeping devices.

  5. Micromagic Clock: Microwave Clock Based on Atoms in an Engineered Optical Lattice

    SciTech Connect

    Beloy, K.; Derevianko, A.; Dzuba, V. A.; Flambaum, V. V.

    2009-03-27

    We propose a new class of atomic microwave clocks based on the hyperfine transitions in the ground state of aluminum or gallium atoms trapped in optical lattices. For such elements magic wavelengths exist at which both levels of the hyperfine doublet are shifted at the same rate by the lattice laser field, canceling its effect on the clock transition. A similar mechanism for the magic wavelengths may work in microwave hyperfine transitions in other atoms which have the fine-structure multiplets in the ground state.

  6. Atomic Clocks and Variations of the FIne Structure Constant

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

    1995-01-01

    We describe a new test for possible variations of the fine structure constant alpha by comparisons of rates between clocks based on hyperfine transitions in alkali atoms with different atomic number Z. H-maser, Cs, and Hg(+) clocks have a different dependence on alpha via relativistic contributions of order (Z-alpha)(sup 2). Recent H-maser vs Hg(+) clock comparison data improve laboratory limits on a time variation by 100-fold to give dot-alpha less than or equal to 3.7 x 10(exp -14)/yr. Future laser cooled clocks (Be(+), Rb, Cs, Hg(+), etc.), when compared, will yield the most sensitive of all tests for dot-alpha/alpha.

  7. Atomic clock based on transient coherent population trapping

    SciTech Connect

    Guo Tao; Deng Ke; Chen Xuzong; Wang Zhong

    2009-04-13

    We proposed a scheme to implement coherent population trapping (CPT) atomic clock based on the transient CPT phenomenon. We proved that the transient transmitted laser power in a typical {lambda} system near CPT resonance features as a damping oscillation. Also, the oscillating frequency is exactly equal to the frequency detuning from the atomic hyperfine splitting. Therefore, we can directly measure the frequency detuning and then compensated to the output frequency of microwave oscillator to get the standard frequency. By this method, we can further simplify the structure of CPT atomic clock, and make it easier to be digitized and miniaturized.

  8. Three-photon-absorption resonance for all-optical atomic clocks

    SciTech Connect

    Zibrov, Sergei; Novikova, Irina; Phillips, David F.; Taichenachev, Aleksei V.; Yudin, Valeriy I.; Walsworth, Ronald L.; Zibrov, Alexander S.

    2005-07-15

    We report an experimental study of an all-optical three-photon-absorption resonance (known as an 'N resonance') and discuss its potential application as an alternative to atomic clocks based on coherent population trapping. We present measurements of the N-resonance contrast, width and light shift for the D{sub 1} line of {sup 87}Rb with varying buffer gases, and find good agreement with an analytical model of this resonance. The results suggest that N resonances are promising for atomic clock applications.

  9. Remote atomic clock synchronization via satellites and optical fibers

    NASA Astrophysics Data System (ADS)

    Piester, D.; Rost, M.; Fujieda, M.; Feldmann, T.; Bauch, A.

    2011-07-01

    In the global network of institutions engaged with the realization of International Atomic Time (TAI), atomic clocks and time scales are compared by means of the Global Positioning System (GPS) and by employing telecommunication satellites for two-way satellite time and frequency transfer (TWSTFT). The frequencies of the state-of-the-art primary caesium fountain clocks can be compared at the level of 10-15 (relative, 1 day averaging) and time scales can be synchronized with an uncertainty of one nanosecond. Future improvements of worldwide clock comparisons will require also an improvement of the local signal distribution systems. For example, the future ACES (atomic clock ensemble in space) mission shall demonstrate remote time scale comparisons at the uncertainty level of 100 ps. To ensure that the ACES ground instrument will be synchronized to the local time scale at the Physikalisch-Technische Bundesanstalt (PTB) without a significant uncertainty contribution, we have developed a means for calibrated clock comparisons through optical fibers. An uncertainty below 40 ps over a distance of 2 km has been demonstrated on the campus of PTB. This technology is thus in general a promising candidate for synchronization of enhanced time transfer equipment with the local realizations of Coordinated Universal Time UTC. Based on these experiments we estimate the uncertainty level for calibrated time transfer through optical fibers over longer distances. These findings are compared with the current status and developments of satellite based time transfer systems, with a focus on the calibration techniques for operational systems.

  10. Applications of Clocks to Space Navigation & "Planetary GPS"

    NASA Technical Reports Server (NTRS)

    Lichten, Stephen M.

    2004-01-01

    The ability to fly atomic clocks on GPS satellites has profoundly defined the capabilities and limitations of GPS in near-Earth applications. It is likely that future infrastructure for Lunar and Mars applications will be constrained by financial factors. The development of a low cost, small, high performance space clock -- or ultrahigh performance space clocks -- could revolutionize and drive the entire approach to GPS-like systems at the Moon (or Mars), and possibly even change the future of GPS at Earth. Many system trade studies are required. The performance of future GPS-like tracking systems at the Moon or Mars will depend critically on clock performance, availability of inertial sensors, and constellation coverage. Example: present-day GPS carry 10(exp -13) clocks and require several updates per day. With 10(exp -15) clocks, a constellation at Mars could operate autonomously with updates just once per month. Use of GPS tracking at the Moon should be evaluated in a technical study.

  11. Quantum Network of Atom Clocks: A Possible Implementation with Neutral Atoms.

    PubMed

    Kómár, P; Topcu, T; Kessler, E M; Derevianko, A; Vuletić, V; Ye, J; Lukin, M D

    2016-08-01

    We propose a protocol for creating a fully entangled Greenberger-Horne-Zeilinger-type state of neutral atoms in spatially separated optical atomic clocks. In our scheme, local operations make use of the strong dipole-dipole interaction between Rydberg excitations, which give rise to fast and reliable quantum operations involving all atoms in the ensemble. The necessary entanglement between distant ensembles is mediated by single-photon quantum channels and collectively enhanced light-matter couplings. These techniques can be used to create the recently proposed quantum clock network based on neutral atom optical clocks. We specifically analyze a possible realization of this scheme using neutral Yb ensembles. PMID:27541452

  12. Quantum Network of Atom Clocks: A Possible Implementation with Neutral Atoms

    NASA Astrophysics Data System (ADS)

    Kómár, P.; Topcu, T.; Kessler, E. M.; Derevianko, A.; Vuletić, V.; Ye, J.; Lukin, M. D.

    2016-08-01

    We propose a protocol for creating a fully entangled Greenberger-Horne-Zeilinger-type state of neutral atoms in spatially separated optical atomic clocks. In our scheme, local operations make use of the strong dipole-dipole interaction between Rydberg excitations, which give rise to fast and reliable quantum operations involving all atoms in the ensemble. The necessary entanglement between distant ensembles is mediated by single-photon quantum channels and collectively enhanced light-matter couplings. These techniques can be used to create the recently proposed quantum clock network based on neutral atom optical clocks. We specifically analyze a possible realization of this scheme using neutral Yb ensembles.

  13. Accurate Optical Lattice Clock with {sup 87}Sr Atoms

    SciTech Connect

    Le Targat, Rodolphe; Baillard, Xavier; Fouche, Mathilde; Brusch, Anders; Tcherbakoff, Olivier; Rovera, Giovanni D.; Lemonde, Pierre

    2006-09-29

    We report a frequency measurement of the {sup 1}S{sub 0}-{sup 3}P{sub 0} transition of {sup 87}Sr atoms in an optical lattice clock. The frequency is determined to be 429 228 004 229 879(5) Hz with a fractional uncertainty that is comparable to state-of-the-art optical clocks with neutral atoms in free fall. The two previous measurements of this transition were found to disagree by about 2x10{sup -13}, i.e., almost 4 times the combined error bar and 4 to 5 orders of magnitude larger than the claimed ultimate accuracy of this new type of clocks. Our measurement is in agreement with one of these two values and essentially resolves this discrepancy.

  14. Heisenberg-limited atom clocks based on entangled qubits.

    PubMed

    Kessler, E M; Kómár, P; Bishof, M; Jiang, L; Sørensen, A S; Ye, J; Lukin, M D

    2014-05-16

    We present a quantum-enhanced atomic clock protocol based on groups of sequentially larger Greenberger-Horne-Zeilinger (GHZ) states that achieves the best clock stability allowed by quantum theory up to a logarithmic correction. Importantly the protocol is designed to work under realistic conditions where the drift of the phase of the laser interrogating the atoms is the main source of decoherence. The simultaneous interrogation of the laser phase with a cascade of GHZ states realizes an incoherent version of the phase estimation algorithm that enables Heisenberg-limited operation while extending the coherent interrogation time beyond the laser noise limit. We compare and merge the new protocol with existing state of the art interrogation schemes, and identify the precise conditions under which entanglement provides an advantage for clock stabilization: it allows a significant gain in the stability for short averaging time. PMID:24877919

  15. Magnetic shielding of the cold atom space clock PHARAO

    NASA Astrophysics Data System (ADS)

    Moric, Igor; Laurent, Philippe; Chatard, Philippe; de Graeve, Charles-Marie; Thomin, Stephane; Christophe, Vincent; Grosjean, Olivier

    2014-09-01

    The space clock PHARAO is an atomic clock based on laser cooled cesium atoms. In order to attenuate magnetic field fluctuation in orbit, PHARAO clock uses three concentric Mumetal magnetic shields combined with several coils to improve the field homogeneity. We have characterized the attenuation and magnetic field homogeneity of the shields used to build the flight model. The average value of attenuation inside the three shields is around 18,000 when the external field is similar to the orbit field (30 μT) and the field homogeneity is lower than 10 nT. These values have not changed after vibrations and thermal tests for the space qualification. Permeability variation of the shields as a function of the intercepted flux has been analyzed.

  16. The Deep Space Atomic Clock: Ushering in a New Paradigm for Radio Navigation and Science

    NASA Technical Reports Server (NTRS)

    Ely, Todd; Seubert, Jill; Prestage, John; Tjoelker, Robert

    2013-01-01

    The Deep Space Atomic Clock (DSAC) mission will demonstrate the on-orbit performance of a high-accuracy, high-stability miniaturized mercury ion atomic clock during a year-long experiment in Low Earth Orbit. DSAC's timing error requirement provides the frequency stability necessary to perform deep space navigation based solely on one-way radiometric tracking data. Compared to a two-way tracking paradigm, DSAC-enabled one-way tracking will benefit navigation and radio science by increasing the quantity and quality of tracking data. Additionally, DSAC also enables fully-autonomous onboard navigation useful for time-sensitive situations. The technology behind the mercury ion atomic clock and a DSAC mission overview are presented. Example deep space applications of DSAC, including navigation of a Mars orbiter and Europa flyby gravity science, highlight the benefits of DSAC-enabled one-way Doppler tracking.

  17. Development of a strontium optical lattice clock for space applications

    NASA Astrophysics Data System (ADS)

    Singh, Yeshpal

    2016-07-01

    With timekeeping being of paramount importance for modern life, much research and major scientific advances have been undertaken in the field of frequency metrology, particularly over the last few years. New Nobel-prize winning technologies have enabled a new era of atomic clocks; namely the optical clock. These have been shown to perform significantly better than the best microwave clocks reaching an inaccuracy of 1.6x10-18 [1]. With such results being found in large lab based apparatus, the focus now has shifted to portability - to enable the accuracy of various ground based clocks to be measured, and compact autonomous performance - to enable such technologies to be tested in space. This could lead to a master clock in space, improving not only the accuracy of technologies on which modern life has come to require such as GPS and communication networks. But also more fundamentally, this could lead to the redefinition of the second and tests of fundamental physics including applications in the fields of ground based and satellite geodesy, metrology, positioning, navigation, transport and logistics etc. Within the European collaboration, Space Optical Clocks (SOC2) [2-3] consisting of various institutes and industry partners across Europe we have tried to tackle this problem of miniaturisation whilst maintaining stability, accuracy (5x10-17) and robustness whilst keeping power consumption to a minimum - necessary for space applications. We will present the most recent results of the Sr optical clock in SOC2 and also the novel compact design features, new methods employed and outlook. References [1] B. J. Bloom, T. L. Nicholson, J. R. Williams, S. L. Campbell, M. Bishof, X. Zhang, W. Zhang, S. L. Bromley, and J. Ye, "An optical lattice clock with accuracy and stability at the 10-18 level," Nature 506, 71-75 (2014). [2] S. Schiller et al. "Towards Neutral-atom Space Optical Clocks (SOC2): Development of high-performance transportable and breadboard optical clocks and

  18. Atomic Clock Based on Opto-Electronic Oscillator

    NASA Technical Reports Server (NTRS)

    Maleki, Lute; Yu, Nan

    2005-01-01

    A proposed highly accurate clock or oscillator would be based on the concept of an opto-electronic oscillator (OEO) stabilized to an atomic transition. Opto-electronic oscillators, which have been described in a number of prior NASA Tech Briefs articles, generate signals at frequencies in the gigahertz range characterized by high spectral purity but not by longterm stability or accuracy. On the other hand, the signals generated by previously developed atomic clocks are characterized by long-term stability and accuracy but not by spectral purity. The proposed atomic clock would provide high spectral purity plus long-term stability and accuracy a combination of characteristics needed to realize advanced developments in communications and navigation. In addition, it should be possible to miniaturize the proposed atomic clock. When a laser beam is modulated by a microwave signal and applied to a photodetector, the electrical output of the photodetector includes a component at the microwave frequency. In atomic clocks of a type known as Raman clocks or coherent-population-trapping (CPT) clocks, microwave outputs are obtained from laser beams modulated, in each case, to create two sidebands that differ in frequency by the amount of a hyperfine transition in the ground state of atoms of an element in vapor form in a cell. The combination of these sidebands produces a transparency in the population of a higher electronic level that can be reached from either of the two ground-state hyperfine levels by absorption of a photon. The beam is transmitted through the vapor to a photodetector. The components of light scattered or transmitted by the atoms in the two hyperfine levels mix in the photodetector and thereby give rise to a signal at the hyperfine- transition frequency. The proposed atomic clock would include an OEO and a rubidium- or cesium- vapor cell operating in the CPT/Raman regime (see figure). In the OEO portion of this atomic clock, as in a typical prior OEO, a

  19. Optical lattice clock with atoms confined in a shallow trap

    SciTech Connect

    Lemonde, Pierre; Wolf, Peter

    2005-09-15

    We study the trap depth requirement for the realization of an optical clock using atoms confined in a lattice. We show that site-to-site tunneling leads to a residual sensitivity to the atom dynamics hence requiring large depths [(50-100)E{sub r} for Sr] to avoid any frequency shift or line broadening of the atomic transition at the 10{sup -17}-10{sup -18} level. Such large depths and the corresponding laser power may, however, lead to difficulties (e.g., higher-order light shifts, two-photon ionization, technical difficulties) and therefore one would like to operate the clock in much shallower traps. To circumvent this problem we propose the use of an accelerated lattice. Acceleration lifts the degeneracy between adjacents potential wells which strongly inhibits tunneling. We show that using the Earth's gravity, much shallower traps (down to 5E{sub r} for Sr) can be used for the same accuracy goal.

  20. Searching for Dark Matter with Atomic Clocks and Laser Interferometry

    NASA Astrophysics Data System (ADS)

    Stadnik, Yevgeny; Flambaum, Victor

    2016-05-01

    We propose new schemes for the direct detection of low-mass bosonic dark matter, which forms a coherently oscillating classical field and resides in the observed galactic dark matter haloes, using atomic clock, atomic spectroscopy and laser interferometry measurements in the laboratory. We have recently shown that such dark matter can produce both a `slow' cosmological evolution and oscillating variations in the fundamental constants. Using recent atomic dysprosium spectroscopy measurements in, we have derived limits on the quadratic interactions of scalar dark matter with ordinary matter that improve on existing constraints by up to 15 orders of magnitude. We have also proposed the use of laser and maser interferometry as novel high-precision platforms to search for dark matter, with effects due to the variation of the electromagnetic fine-structure constant on alterations in the accumulated phase enhanced by up to 14 orders of magnitude. Other possibilities include the use of highly-charged ions, molecules and nuclear clocks.

  1. A high-overtone bulk acoustic wave resonator-oscillator-based 4.596 GHz frequency source: Application to a coherent population trapping Cs vapor cell atomic clock

    SciTech Connect

    Daugey, Thomas; Friedt, Jean-Michel; Martin, Gilles; Boudot, Rodolphe

    2015-11-15

    This article reports on the design and characterization of a high-overtone bulk acoustic wave resonator (HBAR)-oscillator-based 4.596 GHz frequency source. A 2.298 GHz signal, generated by an oscillator constructed around a thermally controlled two-port aluminum nitride-sapphire HBAR resonator with a Q-factor of 24 000 at 68 °C, is frequency multiplied by 2–4.596 GHz, half of the Cs atom clock frequency. The temperature coefficient of frequency of the HBAR is measured to be −23 ppm/ °C at 2.298 GHz. The measured phase noise of the 4.596 GHz source is −105 dB rad{sup 2}/Hz at 1 kHz offset and −150 dB rad{sup 2}/Hz at 100 kHz offset. The 4.596 GHz output signal is used as a local oscillator in a laboratory-prototype Cs microcell-based coherent population trapping atomic clock. The signal is stabilized onto the atomic transition frequency by tuning finely a voltage-controlled phase shifter implemented in the 2.298 GHz HBAR-oscillator loop, preventing the need for a high-power-consuming direct digital synthesis. The short-term fractional frequency stability of the free-running oscillator is 1.8 × 10{sup −9} at one second integration time. In locked regime, the latter is improved in a preliminary proof-of-concept experiment at the level of 6.6 × 10{sup −11} τ{sup −1/2} up to a few seconds and found to be limited by the signal-to-noise ratio of the detected CPT resonance.

  2. Portable compact cold atoms clock topology

    NASA Astrophysics Data System (ADS)

    Pechoneri, R. D.; Müller, S. T.; Bueno, C.; Bagnato, V. S.; Magalhães, D. V.

    2016-07-01

    The compact frequency standard under development at USP Sao Carlos is a cold atoms system that works with a distributed hardware system principle and temporal configuration of the interrogation method of the atomic sample, in which the different operation steps happen in one place: inside the microwave cavity. This type of operation allows us to design a standard much more compact than a conventional one, where different interactions occur in the same region of the apparatus. In this sense, it is necessary to redefine all the instrumentation associated with the experiment. This work gives an overview of the topology we are adopting for the new system.

  3. Resolved Atomic Interaction Sidebands in an Optical Clock Transition

    SciTech Connect

    Bishof, M.; Lin, Y.; Swallows, M. D.; Ye, J.; Rey, A. M.; Gorshkov, A. V.

    2011-06-24

    We report the observation of resolved atomic interaction sidebands (ISB) in the {sup 87}Sr optical clock transition when atoms at microkelvin temperatures are confined in a two-dimensional optical lattice. The ISB are a manifestation of the strong interactions that occur between atoms confined in a quasi-one-dimensional geometry and disappear when the confinement is relaxed along one dimension. The emergence of ISB is linked to the recently observed suppression of collisional frequency shifts. At the current temperatures, the ISB can be resolved but are broad. At lower temperatures, ISB are predicted to be substantially narrower and useful spectroscopic tools in strongly interacting alkaline-earth gases.

  4. Clock Technology Development in the Laser Cooling and Atomic Physics (LCAP) Program

    NASA Technical Reports Server (NTRS)

    Seidel, Dave; Thompson, R. J.; Klipstein, W. M.; Kohel, J.; Maleki, L.

    2000-01-01

    This paper presents the Laser Cooling and Atomic Physics (LCAP) program. It focuses on clock technology development. The topics include: 1) Overview of LCAP Flight Projects; 2) Space Clock 101; 3) Physics with Clocks in microgravity; 4) Space Clock Challenges; 5) LCAP Timeline; 6) International Space Station (ISS) Science Platforms; 7) ISS Express Rack; 8) Space Qualification of Components; 9) Laser Configuration; 10) Clock Rate Comparisons: GPS Carrier Phase Frequency Transfer; and 11) ISS Model Views. This paper is presented in viewgraph form.

  5. A new trapped ion atomic clock based on 201Hg+.

    PubMed

    Burt, Eric A; Taghavi-Larigani, Shervin; Tjoelker, Robert L

    2010-03-01

    High-resolution spectroscopy has been performed on the ground-state hyperfine transitions in trapped (201)Hg+ ions as part of a program to investigate the viability of (201)Hg+ for clock applications. Part of the spectroscopy work was directed at magnetic-field-sensitive hyperfine lines with delta m(F) = 0, which allow accurate Doppler-free measurement of the magnetic field experienced by the trapped ions. Although it is possible to measure Doppler-free magnetic-field-sensitive transitions in the commonly used clock isotope, (199)Hg+, it is more difficult. In this paper, we discuss how this (199)Hg+ feature may be exploited to produce a more stable clock or one requiring less magnetic shielding in environments with magnetic field fluctuations far in excess of what is normally found in the laboratory. We have also determined that in discharge-lamp-based trapped mercury ion clocks, the optical pumping time for (201)Hg+ is about 3 times shorter than that of (199)Hg+ This can be used to reduce dead time in the interrogation cycle for these types of clocks, thereby reducing the impact of local oscillator noise aliasing effects. PMID:20211781

  6. Atomic clock transitions in silicon-based spin qubits.

    PubMed

    Wolfowicz, Gary; Tyryshkin, Alexei M; George, Richard E; Riemann, Helge; Abrosimov, Nikolai V; Becker, Peter; Pohl, Hans-Joachim; Thewalt, Mike L W; Lyon, Stephen A; Morton, John J L

    2013-08-01

    A major challenge in using spins in the solid state for quantum technologies is protecting them from sources of decoherence. This is particularly important in nanodevices where the proximity of material interfaces, and their associated defects, can play a limiting role. Spin decoherence can be addressed to varying degrees by improving material purity or isotopic composition, for example, or active error correction methods such as dynamic decoupling (or even combinations of the two). However, a powerful method applied to trapped ions in the context of atomic clocks is the use of particular spin transitions that are inherently robust to external perturbations. Here, we show that such 'clock transitions' can be observed for electron spins in the solid state, in particular using bismuth donors in silicon. This leads to dramatic enhancements in the electron spin coherence time, exceeding seconds. We find that electron spin qubits based on clock transitions become less sensitive to the local magnetic environment, including the presence of (29)Si nuclear spins as found in natural silicon. We expect the use of such clock transitions will be of additional significance for donor spins in nanodevices, mitigating the effects of magnetic or electric field noise arising from nearby interfaces and gates. PMID:23793304

  7. Time scale algorithms for an inhomogeneous group of atomic clocks

    NASA Technical Reports Server (NTRS)

    Jacques, C.; Boulanger, J.-S.; Douglas, R. J.; Morris, D.; Cundy, S.; Lam, H. F.

    1993-01-01

    Through the past 17 years, the time scale requirements at the National Research Council (NRC) have been met by the unsteered output of its primary laboratory cesium clocks, supplemented by hydrogen masers when short-term stability better than 2 x 10(exp -12)tau(sup -1/2) has been required. NRC now operates three primary laboratory cesium clocks, three hydrogen masers, and two commercial cesium clocks. NRC has been using ensemble averages for internal purposes for the past several years, and has a realtime algorithm operating on the outputs of its high-resolution (2 x 10(exp -13) s at 1 s) phase comparators. The slow frequency drift of the hydrogen masers has presented difficulties in incorporating their short-term stability into the ensemble average, while retaining the long-term stability of the laboratory cesium frequency standards. We report on this work on algorithms for an inhomogeneous ensemble of atomic clocks, and on our initial work on time scale algorithms that could incorporate frequency calibrations at NRC from the next generation of Zacharias fountain cesium frequency standards having frequency accuracies that might surpass 10(exp -15), or from single-trapped-ion frequency standards (Ba+, Sr+,...) with even higher potential accuracies. The requirements for redundancy in all the elements (including the algorithms) of an inhomogeneous ensemble that would give a robust real-time output of the algorithms are presented and discussed.

  8. Generating and probing entangled states for optical atomic clocks

    NASA Astrophysics Data System (ADS)

    Braverman, Boris; Kawasaki, Akio; Vuletic, Vladan

    2016-05-01

    The precision of quantum measurements is inherently limited by projection noise caused by the measurement process itself. Spin squeezing and more complex forms of entanglement have been proposed as ways of surpassing this limitation. In our system, a high-finesse asymmetric micromirror-based optical cavity can mediate the atom-atom interaction necessary for generating entanglement in an 171 Yb optical lattice clock. I will discuss approaches for creating, characterizing, and optimally utilizing these nonclassical states for precision measurement, as well as recent progress toward their realization. This research is supported by DARPA QuASAR, NSF, and NSERC.

  9. Stability of a trapped-atom clock on a chip

    NASA Astrophysics Data System (ADS)

    Szmuk, R.; Dugrain, V.; Maineult, W.; Reichel, J.; Rosenbusch, P.

    2015-07-01

    We present a compact atomic clock interrogating ultracold 87Rb magnetically trapped on an atom chip. Very long coherence times sustained by spin self-rephasing allow us to interrogate the atomic transition with 85% contrast at 5-s Ramsey time. The clock exhibits a fractional frequency stability of 5.8 ×10-13 at 1 s and is likely to integrate into the 10-15 range in less than a day. A detailed analysis of seven noise sources explains the measured frequency stability. Fluctuations in the atom temperature (0.4 nK shot-to-shot) and in the offset magnetic field (5 ×10-6 relative fluctuations shot-to-shot) are the main noise sources together with the local oscillator, which is degraded by the 30% duty cycle. The analysis suggests technical improvements to be implemented in a future second generation setup . The results demonstrate the remarkable degree of technical control that can be reached in an atom chip experiment.

  10. High accuracy measurement of optical atomic clock polarizability

    NASA Astrophysics Data System (ADS)

    Sherman, Jeff; Lemke, Nathan; Hinkley, Nathan; Pizzocaro, Marco; Fox, Richard; Ludlow, Andrew; Oates, Chris

    2012-06-01

    The differential static polarizability of ytterbium optical clock states αclock≡α(^3 0) - α(^1 0) is known theoretically to ˜10%. We report an experimental value of this polarizability, αclock= 36.2612(7) kHz (kV/cm)-2 at 20 parts-per-million (ppm) accuracy [1]. Ultracold ^171Yb atoms held in an optical lattice at the ac-Stark balancing ``magic'' wavelength (759 nm) are surrounded by rigidly spaced transparent conductive planar electrodes. An ultrastable laser (578 nm) is locked to the ^1 0<->^3 0 transition in an interleaved fashion for three electrode conditions: voltage applied, reversed, and grounded. These integrated error signals yield the quadratic Stark shift and a measure of stray fields. The electrode spacing is measured interferometrically in situ. The applied electric field at the site of the atoms deviates at the few ppm level from an infinite-planar model. When last evaluated, the ytterbium optical clock frequency uncertainty was dominated by that of the blackbody Stark shift. We show how this measurement reduces this uncertainty contribution an order of magnitude to a fractional level of 3x10-17.[4pt] [1] J.A. Sherman et al., arXiv:1112.2766 (2011).

  11. 3.4 GHz composite thin film bulk acoustic wave resonator for miniaturized atomic clocks

    SciTech Connect

    Artieda, Alvaro; Muralt, Paul

    2011-06-27

    Triple layer SiO{sub 2}/AlN/SiO{sub 2} composite thin film bulk acoustic wave resonators (TFBARs) were studied for applications in atomic clocks. The TFBAR's were tuned to 3.4 GHz, corresponding to half the hyperfine splitting of the ground state of rubidium {sup 87}Rb atoms. The quality factor (Q) was equal to 2300 and the temperature coefficient of the resonance frequency f{sub r} amounted to 1.5 ppm/K. A figure of merit Qf{sub r} of {approx} 0.8 x 10{sup 13} Hz and a thickness mode coupling factor of 1% were reached. Such figures are ideal for frequency sources in an oscillator circuit that tracks the optical signal in atomic clocks.

  12. Individual Optical Addressing of Atomic Clock Qubits With Stark Shifts

    NASA Astrophysics Data System (ADS)

    Lee, Aaron; Smith, Jacob; Richerme, Phillip; Neyenhuis, Brian; Hess, Paul; Zhang, Jiehang; Monroe, Chris

    2016-05-01

    In recent years, trapped ions have proven to be a versatile quantum information platform, enabled by their long lifetimes and high gate fidelities. Some of the most promising trapped ion systems take advantage of groundstate hyperfine ``clock'' qubits, which are insensitive to background fields to first order. This same insensitivity also makes σz manipulations of the qubit impractical, eliminating whole classes of operations. We prove there exists a fourth-order light shift, or four-photon Stark shift, of the clock states derived from two coherent laser beams whose beatnote is close to the qubit splitting. Using a mode-locked source generates a large light shift with only modest laser powers, making it a practical σz operation on a clock qubit. We experimentally verify and measure the four-photon Stark shift and demonstrate its use to coherently individually address qubits in a chain of 10 Yb 171 ions with low crosstalk. We use this individual addressing to prepare arbitrary product states with high fidelity and also to apply independent σz terms transverse to an Ising Hamiltonian. This work is supported by the ARO Atomic Physics Program, the AFOSR MURI on Quantum Measurement and Verification, and the NSF Physics Frontier Center at JQI.

  13. Compact atomic clock prototype based on coherent population trapping

    NASA Astrophysics Data System (ADS)

    Danet, Jean-Marie; Kozlova, Olga; Yun, Peter; Guérande, Stéphane; de Clercq, Emeric

    2014-08-01

    Toward the next generations of compact atomic clocks, clocks based on coherent population trapping (CPT) offer a very interesting alternative. Thanks to CPT, a quantum interfering process, this technology has made a decisive step in the miniaturization direction. Fractional frequency stability of 1.5x10-10 at 1 s has been demonstrated in commercial devices of a few cm3. The laboratory prototype presented here intends to explore what could be the ultimate stability of a CPT based device. To do so, an original double-Λ optical scheme and a pulsed interrogation have been implemented in order to get a good compromise between contrast and linewidth. A study of two main sources of noise, the relative intensity and the local oscillator (LO) noise, has been performed. By designing simple solutions, it led to a new fractional frequency limitation lower than 4x10-13 at 1 s integration. Such a performance proves that such a technology could rival with classical ones as double resonance clocks.

  14. Magnetic blackbody shift of hyperfine transitions for atomic clocks

    SciTech Connect

    Berengut, J. C.; Flambaum, V. V.; King-Lacroix, J.

    2009-12-15

    We derive an expression for the magnetic blackbody shift of hyperfine transitions such as the cesium primary reference transition which defines the second. The shift is found to be a complicated function of temperature, and has a T{sup 2} dependence only in the high-temperature limit. We also calculate the shift of ground-state p{sub 1/2} hyperfine transitions which have been proposed as new atomic clock transitions. In this case interaction with the p{sub 3/2} fine-structure multiplet may be the dominant effect.

  15. Al-free active region laser diodes at 894 nm for compact Cesium atomic clocks

    NASA Astrophysics Data System (ADS)

    Von Bandel, N.; Bébé Manga Lobé, J.; Garcia, M.; Larrue, A.; Robert, Y.; Vinet, E.; Lecomte, M.; Drisse, O.; Parillaud, O.; Krakowski, M.

    2015-03-01

    Time-frequency applications are in need of high accuracy and high stability clocks. Compact industrial Cesium atomic clocks optically pumped is a promising area that could satisfy these demands. However, the stability of these clocks relies, among others, on the performances of laser diodes that are used for atomic pumping. This issue has led the III-V Lab to commit to the European Euripides-LAMA project that aims to provide competitive compact optical Cesium clocks for earth applications. This work will provide key experience for further space technology qualification. We are in charge of the design, fabrication and reliability of Distributed-Feedback diodes (DFB) at 894nm (D1 line of Cesium) and 852nm (D2 line). The use of D1 line for pumping will provide simplified clock architecture compared to D2 line pumping thanks to simpler atomic transitions and larger spectral separation between lines in the 894nm case. Also, D1 line pumping overcomes the issue of unpumped "dark states" that occur with D2 line. The modules should provide narrow linewidth (<1MHz), very good reliability in time and, crucially, be insensitive to optical feedback. The development of the 894nm wavelength is grounded on our previous results for 852nm DFB. Thus, we show our first results from Al-free active region with InGaAsP quantum well broad-area lasers (100μm width, with lengths ranging from 2mm to 4mm), for further DFB operation at 894nm. We obtained low internal losses below 2cm-1, the external differential efficiency is 0.49W/A with uncoated facets and a low threshold current density of 190A/cm², for 2mm lasers at 20°C.

  16. New Techniques to Test Spin-Gravity Coupling with Atomic Clock

    NASA Technical Reports Server (NTRS)

    Maleki, L.

    2000-01-01

    Recent advances in laser technology have produced the opportunity to realize more stable and accurate atomic clocks, by laser excitation, manipulation and cooling of atoms. In this paper we will describe a new scheme based on the use of lasers with atomic clocks to increase the sensitivity of experimental search for a spin-gravity coupling.

  17. Microwave interrogation cavity for the rubidium space cold atom clock

    NASA Astrophysics Data System (ADS)

    Wei, Ren; Yuan-Ci, Gao; Tang, Li; De-Sheng, Lü; Liang, Liu

    2016-06-01

    The performance of space cold atom clocks (SCACs) should be improved thanks to the microgravity environment in space. The microwave interrogation cavity is a key element in a SCAC. In this paper, we develop a microwave interrogation cavity especially for the rubidium SCAC. The interrogation cavity has two microwave interaction zones with a single feed-in source, which is located at the center of the cavity for symmetric coupling excitation and to ensure that the two interaction zones are in phase. The interrogation cavity has a measured resonance frequency of 6.835056471 GHz with a loaded quality factor of nearly 4200, which shows good agreement with simulation results. We measure the Rabi frequency of the clock transition of the rubidium atom in each microwave interaction zone, and subsequently demonstrate that the distributions of the magnetic field in the two interaction zones are the same and meet all requirements of the rubidium SCAC. Project supported by the National Natural Science Foundation of China (Grant No. 11034008), the Fund from the Ministry of Science and Technology of China (Grant No. 2013YQ09094304), and the Youth Innovation Promotion Association, Chinese Academy of Sciences.

  18. Collisional shifts in optical-lattice atom clocks

    SciTech Connect

    Band, Y. B.; Vardi, A.

    2006-09-15

    We theoretically study the effects of elastic collisions on the determination of frequency standards via Ramsey-fringe spectroscopy in optical-lattice atom clocks. Interparticle interactions of bosonic atoms in multiply occupied lattice sites can cause a linear frequency shift, as well as generate asymmetric Ramsey-fringe patterns and reduce fringe visibility due to interparticle entanglement. We propose a method of reducing these collisional effects in an optical lattice by introducing a phase difference of {pi} between the Ramsey driving fields in adjacent sites. This configuration suppresses site-to-site hopping due to interference of two tunneling pathways, without degrading fringe visibility. Consequently, the probability of double occupancy is reduced, leading to cancellation of collisional shifts.

  19. Advancing Navigation, Timing, and Science with the Deep Space Atomic Clock

    NASA Technical Reports Server (NTRS)

    Ely, Todd A.; Seubert, Jill; Bell, Julia

    2014-01-01

    NASA's Deep Space Atomic Clock mission is developing a small, highly stable mercury ion atomic clock with an Allan deviation of at most 1e-14 at one day, and with current estimates near 3e-15. This stability enables one-way radiometric tracking data with accuracy equivalent to and, in certain conditions, better than current two-way deep space tracking data; allowing a shift to a more efficient and flexible one-way deep space navigation architecture. DSAC-enabled one-way tracking will benefit navigation and radio science by increasing the quantity and quality of tracking data. Additionally, DSAC would be a key component to fully-autonomous onboard radio navigation useful for time-sensitive situations. Potential deep space applications of DSAC are presented, including orbit determination of a Mars orbiter and gravity science on a Europa flyby mission.

  20. In situ dissolution or deposition of Ytterbium (Yb) metal in microhotplate wells for a miniaturized atomic clock.

    PubMed

    Manginell, Ronald P; Moorman, Matthew W; Anderson, John M; Burns, George R; Achyuthan, Komandoor E; Wheeler, David R; Schwindt, Peter D D

    2012-10-22

    Current atomic clocks are burdened by size, weight, power and portability limitations to satisfy a broad range of potential applications. One critical need in the fabrication of a miniaturized atomic clock is small, low-power metallic sources. Exploiting the relatively high vapor pressure of ytterbium (Yb) and its dissolution in anhydrous ammonia, we report two independent techniques for depositing Yb inside a well micromachined into a microhotplate. Subsequent in situ evaporation of Yb from the microhotplate well serves as a low-power metallic source suitable for atomic clocks. The deposition and evaporation of Yb were confirmed using a variety of physicochemical techniques including quartz crystal microbalance, scanning electron microscopy, energy dispersive X-ray spectroscopy, and laser fluorescence. We also describe the fabrication of the microhotplate device, an integral component of our Yb-based miniature atomic clock. The Yb deposition/evaporation on a microhotplate well is thus useful as a low power Yb source during the fabrication of a miniaturized atomic clock, and this technique could be used for other applications requiring a vapor of a metal that has a moderate vapor pressure. PMID:23187228

  1. Coherent-population-trapping resonances with linearly polarized light for all-optical miniature atomic clocks

    SciTech Connect

    Zibrov, Sergei A.; Velichansky, Vladimir L.; Novikova, Irina; Phillips, David F.; Walsworth, Ronald L.; Zibrov, Alexander S.; Taichenachev, Alexey V.; Yudin, Valery I.

    2010-01-15

    We present a joint theoretical and experimental characterization of the coherent population trapping (CPT) resonance excited on the D{sub 1} line of {sup 87}Rb atoms by bichromatic linearly polarized laser light. We observe high-contrast transmission resonances (up to approx =25%), which makes this excitation scheme promising for miniature all-optical atomic clock applications. We also demonstrate cancellation of the first-order light shift by proper choice of the frequencies and relative intensities of the two laser-field components. Our theoretical predictions are in good agreement with the experimental results.

  2. Recent improvements on the atomic fountain clock at SIOM

    NASA Astrophysics Data System (ADS)

    Du, Yuan-Bo; Wei, Rong; Dong, Ri-Chang; Zou, Fan; Wang, Yu-Zhu

    2015-07-01

    We report the recent advance in our rubidium atomic fountain clock (AFC). The parameters of the Ramsey cavity are optimized by balancing the coupling from the two ports. The temperature control system of the Ramsey interaction region is renovated, and the resonant temperature of the Ramsey cavity is regulated to be slightly above the room temperature. The quality of magnetic environment in the Ramsey interaction region is also improved. A new digital-to-analog converter (DAC) circuit that controls the local oscillator is adopted to decrease the noise of the oven-controlled crystal oscillator output. As a result, the short-term fractional frequency stability of 2.7 × 10-13τ-1/2 and the long-term fractional frequency stability of 1.6 × 10-15 at the average time of 32800 s are achieved. Project supported by the National Natural Science Foundation of China (Grant Nos. 61275204 and 91336105).

  3. Improved Tracking of an Atomic-Clock Resonance Transition

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang K.; Tu, Meirong

    2010-01-01

    An improved method of making an electronic oscillator track the frequency of an atomic-clock resonance transition is based on fitting a theoretical nonlinear curve to measurements at three oscillator frequencies within the operational frequency band of the transition (in other words, at three points within the resonance peak). In the measurement process, the frequency of a microwave oscillator is repeatedly set at various offsets from the nominal resonance frequency, the oscillator signal is applied in a square pulse of the oscillator signal having a suitable duration (typically, of the order of a second), and, for each pulse at each frequency offset, fluorescence photons of the transition in question are counted. As described below, the counts are used to determine a new nominal resonance frequency. Thereafter, offsets are determined with respect to the new resonance frequency. The process as described thus far is repeated so as to repeatedly adjust the oscillator to track the most recent estimate of the nominal resonance frequency.

  4. Precision Excited State Lifetime Measurements for Atomic Parity Violation and Atomic Clocks

    NASA Astrophysics Data System (ADS)

    Sell, Jerry; Patterson, Brian; Gearba, Alina; Snell, Jeremy; Knize, Randy

    2016-05-01

    Measurements of excited state atomic lifetimes provide a valuable test of atomic theory, allowing comparisons between experimental and theoretical transition dipole matrix elements. Such tests are important in Rb and Cs, where atomic parity violating experiments have been performed or proposed, and where atomic structure calculations are required to properly interpret the parity violating effect. In optical lattice clocks, precision lifetime measurements can aid in reducing the uncertainty of frequency shifts due to the surrounding blackbody radiation field. We will present our technique for precisely measuring excited state lifetimes which employs mode-locked ultrafast lasers interacting with two counter-propagating atomic beams. This method allows the timing in the experiment to be based on the inherent timing stability of mode-locked lasers, while counter-propagating atomic beams provides cancellation of systematic errors due to atomic motion to first order. Our current progress measuring Rb excited state lifetimes will be presented along with future planned measurements in Yb.

  5. Science Goals of the Primary Atomic Reference Clock in Space (PARCS) Experiment

    NASA Technical Reports Server (NTRS)

    Ashby, N.

    2003-01-01

    The PARCS (Primary Atomic Reference Clock in Space) experiment will use a laser-cooled Cesium atomic clock operating in the microgravity environment aboard the International Space Station (ISS) to provide both advanced tests of gravitational theory and to demonstrate a new cold-atom clock technology for space. PARCS is a joint project of the National Institute of Standards and Technology (NIST), NASA's Jet Propulsion Laboratory (JPL), and the University of Colorado (CU). This paper concentrates on the scientific goals of the PARCS mission. The microgravity space environment allows laser-cooled Cs atoms to have Ramsey times in excess of those feasible on Earth, resulting in improved clock performance. Clock stabilities of 5x10(exp -14) at one second, and accuracies better than 10(exp -16) are projected.

  6. A review of atomic clock technology, the performance capability of present spaceborne and terrestrial atomic clocks, and a look toward the future

    NASA Technical Reports Server (NTRS)

    Vessot, Robert F. C.

    1989-01-01

    Clocks have played a strong role in the development of general relativity. The concept of the proper clock is presently best realized by atomic clocks, whose development as precision instruments has evolved very rapidly in the last decades. To put a historical prospective on this progress since the year AD 1000, the time stability of various clocks expressed in terms of seconds of time error over one day of operation is shown. This stability of operation must not be confused with accuracy. Stability refers to the constancy of a clock operation as compared to that of some other clocks that serve as time references. Accuracy, on the other hand, is the ability to reproduce a previously defined frequency. The issues are outlined that must be considered when accuracy and stability of clocks and oscillators are studied. In general, the most widely used resonances result from the hyperfine interaction of the nuclear magnetic dipole moment and that of the outermost electron, which is characteristic of hydrogen and the alkali atoms. During the past decade hyperfine resonances of ions have also been used. The principal reason for both the accuracy and the stability of atomic clocks is the ability of obtaining very narrow hyperfine transition resonances by isolating the atom in some way so that only the applied stimulating microwave magnetic field is a significant source of perturbation. It is also important to make resonance transitions among hyperfine magnetic sublevels where separation is independent, at least to first order, of the magnetic field. In the case of ions stored in traps operating at high magnetic fields, one selects the trapping field to be consistent with a field-independent transition of the trapped atoms.

  7. Three-dimensional optical lattice clock with bosonic {sup 88}Sr atoms

    SciTech Connect

    Akatsuka, Tomoya; Takamoto, Masao; Katori, Hidetoshi

    2010-02-15

    We present detailed analyses of our recent experiment on the three-dimensional (3D) optical lattice clock with bosonic {sup 88}Sr atoms in which the collisional frequency shift was suppressed by applying a single-occupancy lattice. Frequency shifts in magnetically induced spectroscopy on the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition ({lambda}=698 nm) of {sup 88}Sr were experimentally investigated by referencing a one-dimensional (1D) lattice clock based on spin-polarized {sup 87}Sr atoms. We discuss that the clock stability is limited by the current laser stability as well as the experimental sequence of the clock operation, which may be improved to {sigma}{sub y}({tau})=2x10{sup -16}/{radical}({tau}) by optimizing the cycle time of the clock operation.

  8. Cold-Atom Clocks on Earth and in Space

    NASA Astrophysics Data System (ADS)

    Lemonde, Pierre; Laurent, Philippe; Santarelli, Giorgio; Abgrall, Michel; Sortais, Yvan; Bize, Sebastien; Nicolas, Christophe; Zhang, Shougang; Clairon, Andre; Dimarcq, Noel; Petit, Pierre; Mann, Antony G.; Luiten, Andre N.; Chang, Sheng; Salomon, Christophe

    We present recent progress on microwave clocks that make use of laser-cooled atoms. With an ultra-stable cryogenic sapphire oscillator as interrogation oscillator, a cesium fountain operates at the quantum projection noise limit. With 6 x10^5 detected atoms, the relative frequency stability is 4 x10^-14 &1/2circ, where τ is the integration time in seconds. This stability is comparable to that of hydrogen masers. At τ=2 x10^4s, the measured stability reaches 6 x10^-16. A 87Rb fountain has also been constructed and the 87Rb ground-state hyperfine energy has been compared to the Cs primary standard with a relative accuracy of 2.5 x10^-15. The 87Rb collisional shift is found to be at least 30 times below that of cesium. We also describe a transportable cesium fountain, which will be used for frequency comparisons with an accuracy of 10-15 or below. Finally, we present the details of a space mission for a cesium standard which has been selected by the European Space Agency (ESA) to fly on the International Space Station in 2003.

  9. Enhancing coherence in molecular spin qubits via atomic clock transitions.

    PubMed

    Shiddiq, Muhandis; Komijani, Dorsa; Duan, Yan; Gaita-Ariño, Alejandro; Coronado, Eugenio; Hill, Stephen

    2016-03-17

    Quantum computing is an emerging area within the information sciences revolving around the concept of quantum bits (qubits). A major obstacle is the extreme fragility of these qubits due to interactions with their environment that destroy their quantumness. This phenomenon, known as decoherence, is of fundamental interest. There are many competing candidates for qubits, including superconducting circuits, quantum optical cavities, ultracold atoms and spin qubits, and each has its strengths and weaknesses. When dealing with spin qubits, the strongest source of decoherence is the magnetic dipolar interaction. To minimize it, spins are typically diluted in a diamagnetic matrix. For example, this dilution can be taken to the extreme of a single phosphorus atom in silicon, whereas in molecular matrices a typical ratio is one magnetic molecule per 10,000 matrix molecules. However, there is a fundamental contradiction between reducing decoherence by dilution and allowing quantum operations via the interaction between spin qubits. To resolve this contradiction, the design and engineering of quantum hardware can benefit from a 'bottom-up' approach whereby the electronic structure of magnetic molecules is chemically tailored to give the desired physical behaviour. Here we present a way of enhancing coherence in solid-state molecular spin qubits without resorting to extreme dilution. It is based on the design of molecular structures with crystal field ground states possessing large tunnelling gaps that give rise to optimal operating points, or atomic clock transitions, at which the quantum spin dynamics become protected against dipolar decoherence. This approach is illustrated with a holmium molecular nanomagnet in which long coherence times (up to 8.4 microseconds at 5 kelvin) are obtained at unusually high concentrations. This finding opens new avenues for quantum computing based on molecular spin qubits. PMID:26983539

  10. Enhancing coherence in molecular spin qubits via atomic clock transitions

    NASA Astrophysics Data System (ADS)

    Shiddiq, Muhandis; Komijani, Dorsa; Duan, Yan; Gaita-Ariño, Alejandro; Coronado, Eugenio; Hill, Stephen

    2016-03-01

    Quantum computing is an emerging area within the information sciences revolving around the concept of quantum bits (qubits). A major obstacle is the extreme fragility of these qubits due to interactions with their environment that destroy their quantumness. This phenomenon, known as decoherence, is of fundamental interest. There are many competing candidates for qubits, including superconducting circuits, quantum optical cavities, ultracold atoms and spin qubits, and each has its strengths and weaknesses. When dealing with spin qubits, the strongest source of decoherence is the magnetic dipolar interaction. To minimize it, spins are typically diluted in a diamagnetic matrix. For example, this dilution can be taken to the extreme of a single phosphorus atom in silicon, whereas in molecular matrices a typical ratio is one magnetic molecule per 10,000 matrix molecules. However, there is a fundamental contradiction between reducing decoherence by dilution and allowing quantum operations via the interaction between spin qubits. To resolve this contradiction, the design and engineering of quantum hardware can benefit from a ‘bottom-up’ approach whereby the electronic structure of magnetic molecules is chemically tailored to give the desired physical behaviour. Here we present a way of enhancing coherence in solid-state molecular spin qubits without resorting to extreme dilution. It is based on the design of molecular structures with crystal field ground states possessing large tunnelling gaps that give rise to optimal operating points, or atomic clock transitions, at which the quantum spin dynamics become protected against dipolar decoherence. This approach is illustrated with a holmium molecular nanomagnet in which long coherence times (up to 8.4 microseconds at 5 kelvin) are obtained at unusually high concentrations. This finding opens new avenues for quantum computing based on molecular spin qubits.

  11. Invited review article: The statistical modeling of atomic clocks and the design of time scales.

    PubMed

    Levine, Judah; Ibarra-Manzano, O

    2012-02-01

    I will show how the statistical models that are used to describe the performance of atomic clocks are derived from their internal design. These statistical models form the basis for time scales, which are used to define international time scales such as International Atomic Time and Coordinated Universal Time. These international time scales are realized by ensembles of clocks at national laboratories such as the National Institute of Standards and Technology, and I will describe how ensembles of atomic clocks are characterized and managed. PMID:22380071

  12. Invited Review Article: The statistical modeling of atomic clocks and the design of time scales

    SciTech Connect

    Levine, Judah

    2012-02-15

    I will show how the statistical models that are used to describe the performance of atomic clocks are derived from their internal design. These statistical models form the basis for time scales, which are used to define international time scales such as International Atomic Time and Coordinated Universal Time. These international time scales are realized by ensembles of clocks at national laboratories such as the National Institute of Standards and Technology, and I will describe how ensembles of atomic clocks are characterized and managed.

  13. Highly charged ions for atomic clocks, quantum information, and search for α variation.

    PubMed

    Safronova, M S; Dzuba, V A; Flambaum, V V; Safronova, U I; Porsev, S G; Kozlov, M G

    2014-07-18

    We propose 10 highly charged ions as candidates for the development of next generation atomic clocks, quantum information, and search for α variation. They have long-lived metastable states with transition wavelengths to the ground state between 170-3000 nm, relatively simple electronic structure, stable isotopes, and high sensitivity to α variation (e.g., Sm(14+), Pr(10+), Sm(13+), Nd(10+)). We predict their properties crucial for the experimental exploration and highlight particularly attractive systems for these applications. PMID:25083627

  14. Hyperfine-induced quadrupole moments of alkali-metal-atom ground states and their implications for atomic clocks

    NASA Astrophysics Data System (ADS)

    Derevianko, Andrei

    2016-01-01

    Spherically symmetric ground states of alkali-metal atoms do not posses electric quadrupole moments. However, the hyperfine interaction between nuclear moments and atomic electrons distorts the spherical symmetry of electronic clouds and leads to nonvanishing atomic quadrupole moments. We evaluate these hyperfine-induced quadrupole moments using techniques of relativistic many-body theory and compile results for Li, Na, K, Rb, and Cs atoms. For heavy atoms we find that the hyperfine-induced quadrupole moments are strongly (two orders of magnitude) enhanced by correlation effects. We further apply the results of the calculation to microwave atomic clocks where the coupling of atomic quadrupole moments to gradients of electric fields leads to clock frequency uncertainties. We show that for 133Cs atomic clocks, the spatial gradients of electric fields must be smaller than 30 V /cm2 to guarantee fractional inaccuracies below 10-16.

  15. Cs vapor microcells with Ne-He buffer gas mixture for high operation-temperature miniature atomic clocks.

    PubMed

    Kroemer, E; Abdel Hafiz, M; Maurice, V; Fouilland, B; Gorecki, C; Boudot, R

    2015-07-13

    We report on the characterization of Cs vapor microfabricated cells filled with a Ne-He buffer gas mixture using coherent population trapping (CPT) spectroscopy. The temperature dependence of the Cs clock frequency is found to be canceled at the first order around a so-called inversion temperature higher than 80°C whose value depends on the buffer gas partial pressure ratio. This buffer gas mixture could be well-adapted for the development of miniature atomic clocks devoted to be used in specific applications such as defense and avionic systems with high operating temperature environment (typically higher than 85°C). This solution suggests an alternative to buffer gas mixtures generally used in optically-pumped vapor cell atomic clocks. PMID:26191895

  16. Controlling dipole-dipole frequency shifts in a lattice-based optical atomic clock

    SciTech Connect

    Chang, D.E.; Lukin, M.D.; Ye Jun

    2004-02-01

    Motivated by the ideas of using cold alkaline-earth atoms trapped in an optical lattice for realization of optical atomic clocks, we investigate theoretically the perturbative effects of atom-atom interactions on a clock transition frequency. These interactions are mediated by the dipole fields associated with the optically excited atoms. We predict resonancelike features in the frequency shifts when constructive interference among atomic dipoles occur. We theoretically demonstrate that by fine tuning the coherent dipole-dipole couplings in appropriately designed lattice geometries, the undesirable frequency shifts can be greatly suppressed.

  17. Trapping of Neutral Mercury Atoms and Prospects for Optical Lattice Clocks

    SciTech Connect

    Hachisu, H.; Takamoto, M.; Katori, H.; Miyagishi, K.; Porsev, S. G.; Derevianko, A.; Ovsiannikov, V. D.; Pal'chikov, V. G.

    2008-02-08

    We report vapor-cell magneto-optical trapping of Hg isotopes on the {sup 1}S{sub 0}-{sup 3}P{sub 1} intercombination transition. Six abundant isotopes, including four bosons and two fermions, were trapped. Hg is the heaviest nonradioactive atom trapped so far, which enables sensitive atomic searches for ''new physics'' beyond the standard model. We propose an accurate optical lattice clock based on Hg and evaluate its systematic accuracy to be better than 10{sup -18}. Highly accurate and stable Hg-based clocks will provide a new avenue for the research of optical lattice clocks and the time variation of the fine-structure constant.

  18. Trapping of neutral mercury atoms and prospects for optical lattice clocks.

    PubMed

    Hachisu, H; Miyagishi, K; Porsev, S G; Derevianko, A; Ovsiannikov, V D; Pal'chikov, V G; Takamoto, M; Katori, H

    2008-02-01

    We report vapor-cell magneto-optical trapping of Hg isotopes on the (1)S(0)-(3)P(1) intercombination transition. Six abundant isotopes, including four bosons and two fermions, were trapped. Hg is the heaviest nonradioactive atom trapped so far, which enables sensitive atomic searches for "new physics" beyond the standard model. We propose an accurate optical lattice clock based on Hg and evaluate its systematic accuracy to be better than 10;{-18}. Highly accurate and stable Hg-based clocks will provide a new avenue for the research of optical lattice clocks and the time variation of the fine-structure constant. PMID:18352368

  19. NAVEX: A space shuttle experiment with atomic clocks

    NASA Technical Reports Server (NTRS)

    Starker, S.; Nau, H.; Hamesfahr, J.; Tschiesche, H.

    1983-01-01

    A navigation and time transfer experiment (NAVEX) to be flown within the payload of the first German Spacelab mission D-1 is discussed. The objectives of the experiment are to synchronize distant ground stations with an accuracy of better than 10 nsec and to demonstrate one way ranging with an accuracy of better than 30 m. Spread spectrum signals are used and the related technique is tested. On board a Cs and a Rb clock is used. The relativistic effect of these clocks is about -25 microsec per day. On the ground at least two receiving stations and one transmitting-receiving station will be installed. The synchronization of the ground clocks by shuttle signals is compared to those achieved with clock transportations and with GPS measurements. A system description of this experiment is given containing details on the technical concept, the hardware and the planned data evaluation. The present state of the preparatory work is briefly reviewed.

  20. Improvement in medium long-term frequency stability of the integrating sphere cold atom clock

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Cheng, Huadong; Meng, Yanling; Wan, Jinyin; Xiao, Ling; Wang, Xiumei; Wang, Yaning; Liu, Liang

    2016-07-01

    The medium-long term frequency stability of the integrating sphere cold atom clock was improved.During the clock operation, Rb atoms were cooled and manipulated using cooling light diffusely reflected by the inner surface of a microwave cavity in the clock. This light heated the cavity and caused a frequency drift from the resonant frequency of the cavity. Power fluctuations of the cooling light led to atomic density variations in the cavity's central area, which increased the clock frequency instability through a cavity pulling effect. We overcame these limitations with appropriate solutions. A frequency stability of 3.5E-15 was achieved when the integrating time ? increased to 2E4 s.

  1. The present development of time service in Brazil, with the application of the TV line-10 method for coordination and synchronization of atomic clocks

    NASA Technical Reports Server (NTRS)

    Silva, P. M.; Silva, I. M.

    1974-01-01

    Various methods presently used for the dissemination of time at several levels of precision are described along with future projects in the field. Different aspects of time coordination are reviewed and a list of future laboratories participating in a National Time Scale will be presented. A Brazilian Atomic Time Scale will be obtained from as many of these laboratories as possible. The problem of intercomparison between the Brazilian National Time Scale and the International one will be presented and probable solutions will be discussed. Needs related to the TV Line-10 method will be explained and comments will be made on the legal aspects of time dissemination throughout the country.

  2. Detecting Gravitational Wave Time Dilation Using Space-Based Atomic Clocks

    NASA Astrophysics Data System (ADS)

    Langellier, Nicholas; Kolkowitz, Shimon; Loeb, Avi; Lukin, Mikhail; Maoz, Dani; Ye, Jun; Walsworth, Ronald

    2015-05-01

    Recently, atomic clocks have reached a fractional frequency instability of about 10-16/ √τ . With such precision it may be possible to measure differences in the ticking rates of a spaced-based network of atomic clocks due to time dilation induced by passing gravitational waves. Supermassive black hole binaries arising from galaxy mergers at cosmological distances are predicted to produce gravitational waves at mHz frequencies. The largest variations in clock ticking will occur on the scale of half a wavelength, which for mHz waves is on the 1 AU scale. We assess the sensitivity and feasibility of such a space clock network detector, and compare it to existing means of mHz gravitational wave detection.

  3. Is the time right for a redefinition of the second by optical atomic clocks?

    NASA Astrophysics Data System (ADS)

    Gill, Patrick

    2016-06-01

    Given the dramatic rate of progress in optical atomic clocks over the last decade, this paper presents the current state of play, and considers the possibilities, implications and timescales for a potential redefinition of the SI second in terms of an optical reference transition. In particular, the question of choice of a future standard is addressed, together with the requirements to accurately compare realisations of such standards, both for clocks local to, and remote from each other. Current performances of various optical clock systems are examined and possibilities for moving beyond potential limitations by alternative strategies are outlined.

  4. Higher-order effects on the precision of clocks of neutral atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Ovsiannikov, V. D.; Marmo, S. I.; Palchikov, V. G.; Katori, H.

    2016-04-01

    The recent progress in designing optical lattice clocks with fractional uncertainties below 10-17 requires unprecedented precision in estimating the role of higher-order effects of atom-lattice interactions. In this paper, we present results of systematic theoretical evaluations of the multipole, nonlinear, and anharmonic effects on the optical-lattice-based clocks of alkaline-earth-like atoms. Modifications of the model-potential approach are introduced to minimize discrepancies of theoretical evaluations from the most reliable experimental data. Dipole polarizabilities, hyperpolarizabilities, and multipolar polarizabilities for neutral Ca, Sr, Yb, Zn, Cd, and Hg atoms are calculated in the modified approach.

  5. Single-mode vertical-cavity surface emitting lasers for {sup 87}Rb-based chip-scale atomic clock

    SciTech Connect

    Derebezov, I. A. Haisler, V. A.; Bakarov, A. K.; Kalagin, A. K.; Toropov, A. I.; Kachanova, M. M.; Gavrilova, T. A.; Semenova, O. I.; Tretyakov, D. B.; Beterov, I. I.; Entin, V. M.; Ryabtsev, I. I.

    2010-11-15

    The results of numerical simulation and study of lasing characteristics of semiconductor verticalcavity surface-emitting lasers based on Al{sub x}Ga{sub 1-x}As alloys are presented. Lasers exhibit stable single-mode lasing at a wavelength of 795 nm at low operating currents {approx}1.5 mA and an output power of 350 {mu}W, which offers prospects of their applications in next-generation chip-scale atomic clocks

  6. Optical Lattice Induced Light Shifts in an Yb Atomic Clock

    SciTech Connect

    Barber, Z. W.; Stalnaker, J. E.; Lemke, N. D.; Poli, N.; Oates, C. W.; Fortier, T. M.; Diddams, S. A.; Hollberg, L.; Hoyt, C. W.; Taichenachev, A. V.; Yudin, V. I.

    2008-03-14

    We present an experimental study of the lattice-induced light shifts on the {sup 1}S{sub 0}{yields}{sup 3}P{sub 0} optical clock transition ({nu}{sub clock}{approx_equal}518 THz) in neutral ytterbium. The 'magic' frequency {nu}{sub magic} for the {sup 174}Yb isotope was determined to be 394 799 475(35) MHz, which leads to a first order light shift uncertainty of 0.38 Hz. We also investigated the hyperpolarizability shifts due to the nearby 6s6p{sup 3}P{sub 0}{yields}6s8p{sup 3}P{sub 0}, 6s8p{sup 3}P{sub 2}, and 6s5f{sup 3}F{sub 2} two-photon resonances at 759.708, 754.23, and 764.95 nm, respectively. By measuring the corresponding clock transition shifts near these two-photon resonances, the hyperpolarizability shift was estimated to be 170(33) mHz for a linear polarized, 50 {mu}K deep, lattice at the magic wavelength. These results indicate that the differential polarizability and hyperpolarizability frequency shift uncertainties in a Yb lattice clock could be held to well below 10{sup -17}.

  7. Systematic evaluation of an atomic clock at 2 × 10−18 total uncertainty

    PubMed Central

    Nicholson, T.L.; Campbell, S.L.; Hutson, R.B.; Marti, G.E.; Bloom, B.J.; McNally, R.L.; Zhang, W.; Barrett, M.D.; Safronova, M.S.; Strouse, G.F.; Tew, W.L.; Ye, J.

    2015-01-01

    The pursuit of better atomic clocks has advanced many research areas, providing better quantum state control, new insights in quantum science, tighter limits on fundamental constant variation and improved tests of relativity. The record for the best stability and accuracy is currently held by optical lattice clocks. Here we take an important step towards realizing the full potential of a many-particle clock with a state-of-the-art stable laser. Our 87Sr optical lattice clock now achieves fractional stability of 2.2 × 10−16 at 1 s. With this improved stability, we perform a new accuracy evaluation of our clock, reducing many systematic uncertainties that limited our previous measurements, such as those in the lattice ac Stark shift, the atoms' thermal environment and the atomic response to room-temperature blackbody radiation. Our combined measurements have reduced the total uncertainty of the JILA Sr clock to 2.1 × 10−18 in fractional frequency units. PMID:25898253

  8. Systematic evaluation of an atomic clock at 2 × 10(-18) total uncertainty.

    PubMed

    Nicholson, T L; Campbell, S L; Hutson, R B; Marti, G E; Bloom, B J; McNally, R L; Zhang, W; Barrett, M D; Safronova, M S; Strouse, G F; Tew, W L; Ye, J

    2015-01-01

    The pursuit of better atomic clocks has advanced many research areas, providing better quantum state control, new insights in quantum science, tighter limits on fundamental constant variation and improved tests of relativity. The record for the best stability and accuracy is currently held by optical lattice clocks. Here we take an important step towards realizing the full potential of a many-particle clock with a state-of-the-art stable laser. Our (87)Sr optical lattice clock now achieves fractional stability of 2.2 × 10(-16) at 1 s. With this improved stability, we perform a new accuracy evaluation of our clock, reducing many systematic uncertainties that limited our previous measurements, such as those in the lattice ac Stark shift, the atoms' thermal environment and the atomic response to room-temperature blackbody radiation. Our combined measurements have reduced the total uncertainty of the JILA Sr clock to 2.1 × 10(-18) in fractional frequency units. PMID:25898253

  9. Loading a fountain clock with an enhanced low-velocity intense source of atoms

    NASA Astrophysics Data System (ADS)

    Dobrev, G.; Gerginov, V.; Weyers, S.

    2016-04-01

    We present experimental work for improved atom loading in the optical molasses of a cesium fountain clock, employing a low-velocity intense source of atoms [Lu et al., Phys. Rev. Lett 77, 3331 (1996), 10.1103/PhysRevLett.77.3331], which we modify by adding a dark-state pump laser. With this modification the atom source has a mean flux of 4 ×108 atoms/s at a mean atom velocity of 8.6 m/s. Compared to fountain operation using background gas loading, we achieve a significant increase of the loaded and detected atom number by a factor of 40. Operating the fountain clock with a total number of detected atoms Nat=2.9 ×106 in the quantum projection noise-limited regime, a frequency instability σy(1 s ) =2.7 ×10-14 is demonstrated.

  10. IGS Clock Products for Accurate Geodetic and Timing Applications

    NASA Astrophysics Data System (ADS)

    Senior, K. L.; Ray, J. R.

    2007-12-01

    The performance of any GNSS is intimately related to the characteristics of the satellite clocks, so an understanding of the clock behavior is vital. The accurate products of the IGS enable daily point positions to the sub-cm level and continuous global clock comparisons to the sub-ns level. Time transfers are less accurate than associated positioning because of: 1) difficult-to-measure hardware delays; 2) the limiting pseudorange measurement errors. Both factors arise from characteristics of the pseudorange signals, which are easily degraded by multipath and other effects. The behavior of the satellite clocks are also be important. Over sub-daily intervals, IGS products show that approximate power-law stochastic processes govern all GPS clocks. The Block IIA Rb and Cs clocks obey random walk noise, with the Rb clocks up to nearly an order of magnitude more stable. Due to the high-frequency noise of the onboard Time Keeping system in the newer Block IIR and IIR-M satellites, their Rb clocks are dominantly white noise up to a few 1000 s with standard deviations of 90 to 180 ps. Superposed on this random background, periodic signals are present at four harmonic frequencies, n × (2.0029 ± 0.0005) cycles per day for n = 1, 2, 3, and 4. The equivalent fundamental period is 11.9826 hours, which surprisingly differs from the reported mean GPS orbital period of 11.9659 hours by 60 ± 11 s. We cannot account for this apparent discrepancy but note that a clear relationship between the periodic signals and the orbital dynamics is evidenced for some satellites by modulations of the spectral amplitudes with eclipse season. The Cs clocks are more strongly affected than the Rb clocks. All four harmonics are much smaller for the IIR/IIR-M satellites than for the older blocks. The strong 12- and 6-hour periodics in most GPS clocks dictate that these variations should be modeled in all high-accuracy applications, such as for timescale formation, interpolation of IGS clock products

  11. Atomic ion clock with two ion traps, and method to transfer ions

    NASA Technical Reports Server (NTRS)

    Prestage, John D. (Inventor); Chung, Sang K. (Inventor)

    2011-01-01

    An atomic ion clock with a first ion trap and a second ion trap, where the second ion trap is of higher order than the first ion trap. In one embodiment, ions may be shuttled back and forth from one ion trap to the other by application of voltage ramps to the electrodes in the ion traps, where microwave interrogation takes place when the ions are in the second ion trap, and fluorescence is induced and measured when the ions are in the first ion trap. In one embodiment, the RF voltages applied to the second ion trap to contain the ions are at a higher frequency than that applied to the first ion trap. Other embodiments are described and claimed.

  12. Highly reliable optical system for a rubidium space cold atom clock.

    PubMed

    Ren, Wei; Sun, Yanguang; Wang, Bin; Xia, Wenbing; Qu, Qiuzhi; Xiang, Jingfeng; Dong, Zuoren; Lü, Desheng; Liu, Liang

    2016-05-01

    We describe a highly reliable optical system designed for a rubidium space cold atom clock (SCAC), presenting its design, key technologies, and optical components. All of the optical and electronic components are integrated onto an optimized two-sided 300  mm×290  mm×30  mm optical bench. The compact optical structure and special thermal design ensure that the optical system can pass all of the space environmental qualification tests including both thermal vacuum and mechanical tests. To verify its performance, the optical system is carefully checked before and after each test. The results indicate that this optical system is suitably robust for the space applications for which the rubidium SCAC was built. PMID:27140378

  13. Near-Heisenberg-limited atomic clocks in the presence of decoherence.

    PubMed

    Borregaard, J; Sørensen, A S

    2013-08-30

    The ultimate stability of atomic clocks is limited by the quantum noise of the atoms. To reduce this noise it has been suggested to use entangled atomic ensembles with reduced atomic noise. Potentially this can push the stability all the way to the limit allowed by the Heisenberg uncertainty relation, which is denoted the Heisenberg limit. In practice, however, entangled states are often more prone to decoherence, which may prevent reaching this performance. Here we present an adaptive measurement protocol that in the presence of a realistic source of decoherence enables us to get near-Heisenberg-limited stability of atomic clocks using entangled atoms. The protocol may thus realize the full potential of entanglement for quantum metrology despite the detrimental influence of decoherence. PMID:24033016

  14. Hg-201 (+) CO-Magnetometer for HG-199(+) Trapped Ion Space Atomic Clocks

    NASA Technical Reports Server (NTRS)

    Burt, Eric A. (Inventor); Taghavi, Shervin (Inventor); Tjoelker, Robert L. (Inventor)

    2011-01-01

    Local magnetic field strength in a trapped ion atomic clock is measured in real time, with high accuracy and without degrading clock performance, and the measurement is used to compensate for ambient magnetic field perturbations. First and second isotopes of an element are co-located within the linear ion trap. The first isotope has a resonant microwave transition between two hyperfine energy states, and the second isotope has a resonant Zeeman transition. Optical sources emit ultraviolet light that optically pump both isotopes. A microwave radiation source simultaneously emits microwave fields resonant with the first isotope's clock transition and the second isotope's Zeeman transition, and an optical detector measures the fluorescence from optically pumping both isotopes. The second isotope's Zeeman transition provides the measure of magnetic field strength, and the measurement is used to compensate the first isotope's clock transition or to adjust the applied C-field to reduce the effects of ambient magnetic field perturbations.

  15. Magic Wavelength to Make Optical Lattice Clocks Insensitive to Atomic Motion

    SciTech Connect

    Katori, Hidetoshi; Hashiguchi, Koji; Il'inova, E. Yu.; Ovsiannikov, V. D.

    2009-10-09

    In a standing wave of light, a difference in spatial distributions of multipolar atom-field interactions may introduce atomic-motion dependent clock uncertainties in optical lattice clocks. We show that the magic wavelength can be defined so as to eliminate the spatial mismatch in electric dipole, magnetic dipole, and electric quadrupole interactions for specific combinations of standing waves by allowing a spatially constant light shift arising from the latter two interactions. Experimental prospects of such lattices used with a blue magic wavelength are discussed.

  16. Exploring Ramsey-coherent population trapping atomic clock realized with pulsed microwave modulated laser

    SciTech Connect

    Yang, Jing; Yun, Peter; Tian, Yuan; Tan, Bozhong; Gu, Sihong

    2014-03-07

    A scheme for a Ramsey-coherent population trapping (CPT) atomic clock that eliminates the acousto-optic modulator (AOM) is proposed and experimentally studied. Driven by a periodically microwave modulated current, the vertical-cavity surface-emitting laser emits a continuous beam that switches between monochromatic and multichromatic modes. Ramsey-CPT interference has been studied with this mode-switching beam. In eliminating the AOM, which is used to generate pulsed laser in conventional Ramsey-CPT atomic clock, the physics package of the proposed scheme is virtually the same as that of a conventional compact CPT atomic clock, although the resource budget for the electronics will slightly increase as a microwave switch should be added. By evaluating and comparing experimentally recorded signals from the two Ramsey-CPT schemes, the short-term frequency stability of the proposed scheme was found to be 46% better than the scheme with AOM. The experimental results suggest that the implementation of a compact Ramsey-CPT atomic clock promises better frequency stability.

  17. Low-threshold short-cavity diode laser for a miniature atomic clock

    SciTech Connect

    Kargapol'tsev, Sergei V; Velichansky, Vladimir L; Vasil'ev, V V; Kobyakova, M Sh; Morozyuk, A V; Shiryaeva, N V; Konyaev, V P

    2009-06-30

    Short-cavity diode lasers (SCDLs) emitting at the 894-nm D{sub 1} line of caesium are developed. Low threshold currents and power consumption will make it possible to use these lasers in chip-size atomic clocks (CSACs) and magnetometers. The SCDL parameters are comparable with the parameters of surface-emitting lasers. (lasers)

  18. LASERS: Low-threshold short-cavity diode laser for a miniature atomic clock

    NASA Astrophysics Data System (ADS)

    Kargapol'tsev, Sergei V.; Velichansky, Vladimir L.; Vasil'ev, V. V.; Kobyakova, M. Sh; Morozyuk, A. V.; Shiryaeva, N. V.; Konyaev, V. P.

    2009-06-01

    Short-cavity diode lasers (SCDLs) emitting at the 894-nm D1 line of caesium are developed. Low threshold currents and power consumption will make it possible to use these lasers in chip-size atomic clocks (CSACs) and magnetometers. The SCDL parameters are comparable with the parameters of surface-emitting lasers.

  19. Clock Technology Development for the Laser Cooling and Atomic Physics (LCAP) Program

    NASA Technical Reports Server (NTRS)

    Klipstein, W. M.; Thompson, R. J.; Seidel, D. J.; Kohel, J.; Maleki, L.

    1998-01-01

    The Time and Frequency Sciences and Technology Group at Jet Propulsion Laboratory (JPL) has developed a laser cooling capability for flight and has been selected by NASA to support the Laser-Cooling and Atomic Physics (LCAP) program. Current work in the group includes design and development for tee two laser-cooled atomic clock experiments which have been selected for flight on the International Space Station.

  20. Absolute frequency of an atomic hydrogen maser clock

    NASA Technical Reports Server (NTRS)

    Peters, H. E.; Hall, R. G.; Percival, D. B.

    1972-01-01

    An accurate determination was made of the unperturbed atomic hydrogen ground state hyperfine transition frequency (F=1,m=0 - F=0,m=0) in reference to present world wide realizations of internationally defined time interval. In relation to the international atomic time system, the composite value is 1,420,405,751.7755 plus or minus 0.0031 HZ.

  1. Atomic fountain clock with very high frequency stability employing a pulse-tube-cryocooled sapphire oscillator.

    PubMed

    Takamizawa, Akifumi; Yanagimachi, Shinya; Tanabe, Takehiko; Hagimoto, Ken; Hirano, Iku; Watabe, Ken-ichi; Ikegami, Takeshi; Hartnett, John G

    2014-09-01

    The frequency stability of an atomic fountain clock was significantly improved by employing an ultra-stable local oscillator and increasing the number of atoms detected after the Ramsey interrogation, resulting in a measured Allan deviation of 8.3 × 10(-14)τ(-1/2)). A cryogenic sapphire oscillator using an ultra-low-vibration pulse-tube cryocooler and cryostat, without the need for refilling with liquid helium, was applied as a local oscillator and a frequency reference. High atom number was achieved by the high power of the cooling laser beams and optical pumping to the Zeeman sublevel m(F) = 0 employed for a frequency measurement, although vapor-loaded optical molasses with the simple (001) configuration was used for the atomic fountain clock. The resulting stability is not limited by the Dick effect as it is when a BVA quartz oscillator is used as the local oscillator. The stability reached the quantum projection noise limit to within 11%. Using a combination of a cryocooled sapphire oscillator and techniques to enhance the atom number, the frequency stability of any atomic fountain clock, already established as primary frequency standard, may be improved without opening its vacuum chamber. PMID:25167146

  2. Theory of magic optical traps for Zeeman-insensitive clock transitions in alkali-metal atoms

    SciTech Connect

    Derevianko, Andrei

    2010-05-15

    Precision measurements and quantum-information processing with cold atoms may benefit from trapping atoms with specially engineered, 'magic' optical fields. At the magic trapping conditions, the relevant atomic properties remain immune to strong perturbations by the trapping fields. Here we develop a theoretical analysis of magic trapping for especially valuable Zeeman-insensitive clock transitions in alkali-metal atoms. The involved mechanism relies on applying a magic bias B field along a circularly polarized trapping laser field. We map out these B fields as a function of trapping laser wavelength for all commonly used alkalis. We also highlight a common error in evaluating Stark shifts of hyperfine manifolds.

  3. Spin waves and collisional frequency shifts of a trapped-atom clock.

    PubMed

    Maineult, Wilfried; Deutsch, Christian; Gibble, Kurt; Reichel, Jakob; Rosenbusch, Peter

    2012-07-13

    We excite spin waves with spatially inhomogeneous Ramsey pulses and study the resulting frequency shifts of a chip-scale atomic clock of trapped 87Rb. The density-dependent frequency shifts of the hyperfine transition simulate the s-wave collisional frequency shifts of fermions, including those of optical lattice clocks. As the spin polarizations oscillate in the trap, the frequency shift reverses and it depends on the area of the second Ramsey pulse, exhibiting a predicted beyond mean-field frequency shift. Numerical and analytic models illustrate these observed behaviors. PMID:23030137

  4. Towards rotation sensing with a single atomic clock

    NASA Astrophysics Data System (ADS)

    Fernholz, Thomas; Stevenson, Robin; Hush, Michael R.; Lesanovsky, Igor V.; Bishop, Thomas; Gentile, Fabio; Jammi, Sindhu; Pyragius, Tadas; Bason, Mark G.; Mas, Hèctor; Pandey, Saurabh; Vasilakis, Georgios; Poulios, Konstantinos; von Klitzing, Wolf

    2016-04-01

    We discuss a scheme to implement a gyroscopic atom sensor with magnetically trapped ultra-cold atoms. Unlike standard light or matter wave Sagnac interferometers no free wave propagation is used. Interferometer operation is controlled only with static, radio-frequency and microwave magnetic fields, which removes the need for interferometric stability of optical laser beams. Due to the confinement of atoms, the scheme may allow the construction of small scale portable sensors. We discuss the main elements of the scheme and report on recent results and efforts towards its experimental realization.

  5. Formulation of geopotential difference determination using optical-atomic clocks onboard satellites and on ground based on Doppler cancellation system

    NASA Astrophysics Data System (ADS)

    Shen, Ziyu; Shen, Wen-Bin; Zhang, Shuangxi

    2016-06-01

    In this study we propose an approach for determining the geopotential difference using high-frequency-stability microwave links between satellite and ground station based on Doppler cancelation system. Suppose a satellite and a ground station are equipped with precise optical-atomic clocks and oscillators. The ground oscillator emits a signal with frequency fa towards the satellite and the satellite receiver (connected with the satellite oscillator) receives this signal with frequency fb which contains the gravitational frequency shift effect and other signals and noises. After receiving this signal, the satellite oscillator transmits and emits respectively two signals with frequencies fb and fc towards the ground station. Via Doppler cancellation technique, the geopotential difference between the satellite and the ground station can be determined based on gravitational frequency shift equation by a combination of these three frequencies. For arbitrary two stations on ground, based on similar procedures as described above, we may determine the geopotential difference between these two stations via a satellite. Our analysis shows that the accuracy can reach 1 {m^2/s^2} based on the clocks' inaccuracy of about 10-17 (s/s) level. Since optical-atomic clocks with instability around 10-18 in several hours and inaccuracy around 10-18 level have been generated in laboratory, the proposed approach may have prospective applications in geoscience, and especially, based on this approach a unified world height system could be realized with one-centimeter level accuracy in the near future.

  6. Magic Traps for Clock Transitions in Neutral Cesium Atoms

    NASA Astrophysics Data System (ADS)

    Carr, Alexander; Saffman, Mark

    2014-05-01

    In a system of trapped atoms errors in quantum gates and precision spectroscopy can arise from a differential shift in atomic transitions caused by gradients in the electric and magnetic fields. The thermal motion of an atom in a trap allows it to sample changes in these two fields resulting in a constantly shifting transition frequency. ``Magic'' traps minimize this source of noise by finding experimental conditions where the first-order sensitivity to gradients is nulled. We present refinements to calculations of the Zeeman and A.C. Stark Shift for qubit states in the ground hyperfine state manifold of neutral Cesium atoms. We follow this with a discussion of implications for traps insensitive to electric fields, magnetic fields or both simultaneously.

  7. The Physics of Miniature Atomic Clocks: 0-0 Versus "End" Transitions

    NASA Astrophysics Data System (ADS)

    Post, Amber; Jau, Yuan-Yu; Kuzma, Nicholas; Happer, William

    2003-05-01

    The majority of traditional atomic-clock designs are based on the 0-0 hyperfine transition of a Cs 133 atom. We are currently investigating the advantages of operating a miniature optical atomic clock using the "end" transitions, e.g. connecting states |f=1, mf =+/-1> and |f=2, mf=+/-2> in 87Rb. In our paper we present extensive new measurements of relevant relaxation rates, such as those due to spin-exchange collisions, buffer-gas pressure shifts, Carver Rates and others, which ultimately determine the choices of an operating regime for the miniature optical atomic clock. The relationship between these rates is non-trivial: for example, using higher laser power will increase polarization and reduce the spin-exchange rate [1], but it can simultaneously increase the linewidth due to the optical pumping rate. The dependence of these and other relaxation rates on the cell size, temperature, pressure, a choice of buffer gas, and other parameters will be reported. Based on these measured rates, our modeling can be used to predict the transition linewidths, signal-to-noise ratios and thus the stability of the clock in different operating regimes. The trade-off between the stability of the clock and the desired small cell size and low power consumption needs to be carefully considered in order to optimize our design. In our experiments we used optical, microwave, and radio-frequency excitation to study hyperfine and Zeeman resonance lines in heated glass cells containing pure-isotope alkali-metal vapor and buffer gasses (N2, Ar, He, etc.) at low (0 - 10 G) magnetic fields. Simultaneous use of light, microwave and radio-frequency fields allowed us to calibrate surrounding magnetic fields by observing the corresponding shifts of the resonance, thus leading us to a quantitative understanding of our system. [1] S. Appelt, A. B. Baranga, A. R. Young, W. Happer, Phys. Rev. A 59, 2078 (1999).

  8. Microfabricated chip-scale rubidium plasma light source for miniature atomic clocks.

    PubMed

    Venkatraman, Vinu; Pétremand, Yves; Affolderbach, Christoph; Mileti, Gaetano; de Rooij, Nico F; Shea, Herbert

    2012-03-01

    We present the microfabrication and characterization of a low-power, chip-scale Rb plasma light source, designed for optical pumping in miniature atomic clocks. A dielectric barrier discharge (DBD) configuration is used to ignite a Rb plasma in a micro-fabricated Rb vapor cell on which external indium electrodes were deposited. The device is electrically driven at frequencies between 1 and 36 MHz, and emits 140 μW of stable optical power while coupling less than 6 mW of electrical power to the discharge cell. Optical powers of up to 15 and 9 μW are emitted on the Rb D2 and D1 lines, respectively. Continuous operation of the light source for several weeks has been demonstrated, showing its capacity to maintain stable optical excitation of Rb atoms in chip-scale double-resonance atomic clocks. PMID:22481778

  9. Possibility of triple magic trapping of clock and Rydberg states of divalent atoms in optical lattices

    NASA Astrophysics Data System (ADS)

    Topcu, T.; Derevianko, A.

    2016-07-01

    We predict the possibility of ‘triply magic’ optical lattice trapping of neutral divalent atoms. In such a lattice, the {}1{{{S}}}0 and {}3{{{P}}}0 clock states and an additional Rydberg state experience identical optical potentials, fully mitigating detrimental effects of the motional decoherence. In particular, we show that this triply magic trapping condition can be satisfied for Yb atom at optical wavelengths and for various other divalent systems (Ca, Mg, Hg and Sr) in the UV region. We assess the quality of triple magic trapping conditions by estimating the probability of excitation out of the motional ground state as a result of the excitations between the clock and the Rydberg states. We also calculate trapping laser-induced photoionization rates of divalent Rydberg atoms at magic frequencies. We find that such rates are below the radiative spontaneous-emission rates, due to the presence of Cooper minima in photoionization cross-sections.

  10. Clock Shifts of Optical Transitions in Ultracold Atomic Gases

    SciTech Connect

    Yu Zhenhua; Pethick, C. J.

    2010-01-08

    We calculate the shift, due to interatomic interactions, of an optical transition in an atomic Fermi gas trapped in an optical lattice, as in recent experiments of Campbell et al.[Science 324, 360 (2009)]. Using a pseudospin formalism to describe the density matrix of atoms, we derive a Bloch equation which incorporates both spatial inhomogeneity of the probe laser field and interatomic interactions. Expressions are given for the frequency shift as a function of pulse duration, detuning of the probe laser, and the spatial dependence of the electric field of the probe beam. In the low temperature semiclassical regime, we find that the magnitude of the shift is proportional to the temperature.

  11. Optical clocks and relativity.

    PubMed

    Chou, C W; Hume, D B; Rosenband, T; Wineland, D J

    2010-09-24

    Observers in relative motion or at different gravitational potentials measure disparate clock rates. These predictions of relativity have previously been observed with atomic clocks at high velocities and with large changes in elevation. We observed time dilation from relative speeds of less than 10 meters per second by comparing two optical atomic clocks connected by a 75-meter length of optical fiber. We can now also detect time dilation due to a change in height near Earth's surface of less than 1 meter. This technique may be extended to the field of geodesy, with applications in geophysics and hydrology as well as in space-based tests of fundamental physics. PMID:20929843

  12. Collective non-equilibrium spin exchange in cold alkaline-earth atomic clocks

    NASA Astrophysics Data System (ADS)

    Acevedo, Oscar Leonardo; Rey, Ana Maria

    2016-05-01

    Alkaline-earth atomic (AEA) clocks have recently been shown to be reliable simulators of two-orbital SU(N) quantum magnetism. In this work, we study the non-equilibrium spin exchange dynamics during the clock interrogation of AEAs confined in a deep one-dimensional optical lattice and prepared in two nuclear levels. The two clock states act as an orbital degree of freedom. Every site in the lattice can be thought as populated by a frozen set of vibrational modes collectively interacting via predominantly p-wave collisions. Due to the exchange coupling, orbital state transfer between atoms with different nuclear states is expected to happen. At the mean field level, we observe that in addition to the expected suppression of population transfer in the presence of a large magnetic field, that makes the single particle levels off-resonance, there is also an interaction induced suppression for initial orbital population imbalance. This suppression resembles the macroscopic self-trapping mechanism seen in bosonic systems. However, by performing exact numerical solutions and also by using the so-called Truncated Wigner Approximation, we show that quantum correlations can significantly modify the mean field suppression. Our predictions should be testable in optical clock experiments. Project supported by NSF-PHY-1521080, JILA-NSF-PFC-1125844, ARO, AFOSR, and MURI-AFOSR.

  13. Gravity tests, differential accelerometry and interleaved clocks with cold atom interferometers

    NASA Astrophysics Data System (ADS)

    Biedermann, Grant

    The remarkable success of light-pulse atom interferometer techniques has motivated competitive research in precision metrology. Gravimeters, gyroscopes and gradiometers based on these techniques are all at the forefront of their respective measurement classes. We show here the progress toward a compact gravity gradiometer for precision gravitational tests. It is well known that these devices suffer from environmental perturbations. Spurious noise may enter through beam steering effects which cause uncommon coupling to gravity in the two accelerometers. The horizontal configuration used here is particularly sensitive to this effect. Additionally, laser frequency noise may significantly limit the interferometer sensitivity. In our device, we have overcome these obstacles to achieve a differential acceleration sensitivity of 4.2 x 10-9g/ Hz over a 70 cm baseline. This corresponds to a phase noise of 3.1 mrad/ Hz inferred per interferometer which is the best performance achieved in such a system. Using this device, we demonstrate a proof-of-concept measurement of the gravitational constant with a precision of 3 x 10-4, which is competitive with the present limit of 1 x 10-4. I discuss improvements which can enable uncertainties falling below 10 -5. This experiment can also be interpreted as a test of the inverse square law which statistically constrains a putative Yukawa type fifth force to 8 x 10-3 near the poorly known length scale of 20 cm. Limits exceeding 10-4 appear to be feasible. We also perform an experiment which tests the atom interferometer in the context of a time-dependent gravity potential. Furthermore, we demonstrate a technique by which one may temporally link interferometer measurements together to provide continuous sampling. This can be used to eliminate the inertial sensor analog of the Dick effect and has important applications in the fields of optical and atomic clocks.

  14. Microwave lensing frequency shift of the PHARAO laser-cooled microgravity atomic clock

    NASA Astrophysics Data System (ADS)

    Peterman, Phillip; Gibble, Kurt; Laurent, Phillipe; Salomon, Christophe

    2016-04-01

    We evaluate the microwave lensing frequency shift of the microgravity laser-cooled caesium clock PHARAO. We find microwave lensing frequency shifts of δν/ν  =  11  ×  10-17 to 13  ×  10-17, larger than the shift of typical fountain clocks. The shift has a weak dependence on PHARAO parameters, including the atomic temperature, size of the atomic cloud, detection laser intensities, and the launch velocity. We also find the lensing frequency shift to be insensitive to selection and detection spatial inhomogeneities and the expected low-frequency vibrations. We conservatively assign a nominal microwave lensing frequency uncertainty of  ±4  ×  10-17.

  15. Testing general relativity and alternative theories of gravity with space-based atomic clocks and atom interferometers

    NASA Astrophysics Data System (ADS)

    Bondarescu, Ruxandra; Schärer, Andreas; Jetzer, Philippe; Angélil, Raymond; Saha, Prasenjit; Lundgren, Andrew

    2015-05-01

    The successful miniaturisation of extremely accurate atomic clocks and atom interferometers invites prospects for satellite missions to perform precision experiments. We discuss the effects predicted by general relativity and alternative theories of gravity that can be detected by a clock, which orbits the Earth. Our experiment relies on the precise tracking of the spacecraft using its observed tick-rate. The spacecraft's reconstructed four-dimensional trajectory will reveal the nature of gravitational perturbations in Earth's gravitational field, potentially differentiating between different theories of gravity. This mission can measure multiple relativistic effects all during the course of a single experiment, and constrain the Parametrized Post-Newtonian Parameters around the Earth. A satellite carrying a clock of fractional timing inaccuracy of Δ f / f ˜ 10-16 in an elliptic orbit around the Earth would constrain the PPN parameters |β - 1|, |γ - 1| ≲ 10-6. We also briefly review potential constraints by atom interferometers on scalar tensor theories and in particular on Chameleon and dilaton models.

  16. A compact, high-performance all optical atomic clock based on telecom lasers

    NASA Astrophysics Data System (ADS)

    Burke, John H.; Lemke, Nathan D.; Phelps, Gretchen R.; Martin, Kyle W.

    2016-03-01

    We discuss an optical atomic clock based on a two-photon transition at 778 nm in rubidium. In particular, we discuss the fundamental limitations to the short-term stability of a system based on a commercial C-band telecom laser as opposed to a near infrared laser. We show that this system is fundamentally capable of besting a hydrogen MASER in frequency stability and size.

  17. Distinguishing between evidence and its explanations in the steering of atomic clocks

    SciTech Connect

    Myers, John M.; Hadi Madjid, F.

    2014-11-15

    Quantum theory reflects within itself a separation of evidence from explanations. This separation leads to a known proof that: (1) no wave function can be determined uniquely by evidence, and (2) any chosen wave function requires a guess reaching beyond logic to things unforeseeable. Chosen wave functions are encoded into computer-mediated feedback essential to atomic clocks, including clocks that step computers through their phases of computation and clocks in space vehicles that supply evidence of signal propagation explained by hypotheses of spacetimes with metric tensor fields. The propagation of logical symbols from one computer to another requires a shared rhythm—like a bucket brigade. Here we show how hypothesized metric tensors, dependent on guesswork, take part in the logical synchronization by which clocks are steered in rate and position toward aiming points that satisfy phase constraints, thereby linking the physics of signal propagation with the sharing of logical symbols among computers. Recognizing the dependence of the phasing of symbol arrivals on guesses about signal propagation transports logical synchronization from the engineering of digital communications to a discipline essential to physics. Within this discipline we begin to explore questions invisible under any concept of time that fails to acknowledge unforeseeable events. In particular, variation of spacetime curvature is shown to limit the bit rate of logical communication. - Highlights: • Atomic clocks are steered in frequency toward an aiming point. • The aiming point depends on a chosen wave function. • No evidence alone can determine the wave function. • The unknowability of the wave function has implications for spacetime curvature. • Variability in spacetime curvature limits the bit rate of communications.

  18. Aging studies on micro-fabricated alkali buffer-gas cells for miniature atomic clocks

    SciTech Connect

    Abdullah, S.; Affolderbach, C.; Gruet, F.; Mileti, G.

    2015-04-20

    We report an aging study on micro-fabricated alkali vapor cells using neon as a buffer gas. An experimental atomic clock setup is used to measure the cell's intrinsic frequency, by recording the clock frequency shift at different light intensities and extrapolating to zero intensity. We find a drift of the cell's intrinsic frequency of (−5.2 ± 0.6) × 10{sup −11}/day and quantify deterministic variations in sources of clock frequency shifts due to the major physical effects to identify the most probable cause of the drift. The measured drift is one order of magnitude stronger than the total frequency variations expected from clock parameter variations and corresponds to a slow reduction of buffer gas pressure inside the cell, which is compatible with the hypothesis of loss of Ne gas from the cell due to its permeation through the cell windows. A negative drift on the intrinsic cell frequency is reproducible for another cell of the same type. Based on the Ne permeation model and the measured cell frequency drift, we determine the permeation constant of Ne through borosilicate glass as (5.7 ± 0.7) × 10{sup −22} m{sup 2} s{sup −1 }Pa{sup −1} at 81 °C. We propose this method based on frequency metrology in an alkali vapor cell atomic clock setup based on coherent population trapping for measuring permeation constants of inert gases.

  19. Hyperfine-induced electric dipole contributions to the electric octupole and magnetic quadrupole atomic clock transitions

    NASA Astrophysics Data System (ADS)

    Dzuba, V. A.; Flambaum, V. V.

    2016-05-01

    Hyperfine-induced electric dipole contributions may significantly increase probabilities of otherwise very weak electric octupole and magnetic quadrupole atomic clock transitions (e.g., transitions between s and f electron orbitals). These transitions can be used for exceptionally accurate atomic clocks, quantum information processing, and the search for dark matter. They are very sensitive to new physics beyond the standard model, such as temporal variation of the fine-structure constant, the Lorentz invariance, and Einstein equivalence principle violation. We formulate conditions under which the hyperfine-induced electric dipole contribution dominates and perform calculations of the hyperfine structure and E3, M2 and the hyperfine-induced E1 transition rates for a large number of atoms and ions of experimental interest. Due to the hyperfine quenching the electric octupole clock transition in +173Yb is 2 orders of magnitude stronger than that in currently used +171Yb. Some enhancement is found in 13+143Nd, 14+149Pm, 14+147Sm, and 15+147Sm ions.

  20. Controlling the magnetic-field sensitivity of atomic-clock states by microwave dressing

    NASA Astrophysics Data System (ADS)

    Sárkány, L.; Weiss, P.; Hattermann, H.; Fortágh, J.

    2014-11-01

    We demonstrate control of the differential Zeeman shift between clock states of ultracold rubidium atoms by means of nonresonant microwave dressing. Using the dc field dependence of the microwave detuning, we suppress the first- and second-order differential Zeeman shift in magnetically trapped 87Rb atoms. By dressing the state pair 5 S1 /2 F =1 , mF=-1 and F =2 , mF=1 , a residual frequency spread of <0.1 Hz in a range of 100 mG around a chosen magnetic offset field can be achieved. This is one order of magnitude smaller than the shift of the bare states at the magic field of the Breit-Rabi parabola. We further identify double magic points, around which the clock frequency is insensitive to fluctuations both in the magnetic field and in the dressing Rabi frequency. The technique is compatible with chip-based cold-atom systems and allows the creation of clock and qubit states with reduced sensitivity to magnetic-field noise.

  1. Scheme for a compact cold-atom clock based on diffuse laser cooling in a cylindrical cavity

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Meng, Yanling; Wan, Jinyin; Wang, Xiumei; Wang, Yaning; Xiao, Ling; Cheng, Huadong; Liu, Liang

    2015-12-01

    We present a scheme for a compact rubidium cold-atom clock which performs diffuse light cooling, microwave interrogation, and detection of the clock signal in a cylindrical microwave cavity. The diffuse light is produced by laser light reflection at the inner surface of the microwave cavity. The pattern of the injected laser beams is specially designed to accumulate the majority of the cold atoms in the center of the microwave cavity. Microwave interrogation of the cold atoms in the cavity leads to Ramsey fringes, which have a linewidth of 24.5 Hz with a contrast of 95.6 % when the free evolution time is 20 ms. Recently, a frequency stability of 7.3 ×10-13τ-1 /2 has been achieved. The scheme of this physical package can largely reduce the cold-atom clock complexity and increase clock performance.

  2. Low-temperature indium-bonded alkali vapor cell for chip-scale atomic clocks

    NASA Astrophysics Data System (ADS)

    Straessle, R.; Pellaton, M.; Affolderbach, C.; Pétremand, Y.; Briand, D.; Mileti, G.; de Rooij, N. F.

    2013-02-01

    A low-temperature sealing technique for micro-fabricated alkali vapor cells for chip-scale atomic clock applications is developed and evaluated. A thin-film indium bonding technique was used for sealing the cells at temperatures of ≤140 °C. These sealing temperatures are much lower than those reported for other approaches, and make the technique highly interesting for future micro-fabricated cells, using anti-relaxation wall coatings. Optical and microwave spectroscopy performed on first indium-bonded cells without wall coatings are used to evaluate the cleanliness of the process as well as a potential leak rate of the cells. Both measurements confirm a stable pressure inside the cell and therefore an excellent hermeticity of the indium bonding. The double-resonance measurements performed over several months show an upper limit for the leak rate of 1.5 × 10-13 mbar.l/s. This is in agreement with additional leak-rate measurements using a membrane deflection method on indium-bonded test structures.

  3. Quantum projection noise limited stability of a 88Sr+ atomic clock

    NASA Astrophysics Data System (ADS)

    Jian, B.; Dubé, P.; Madej, A. A.

    2016-06-01

    The evaluated accuracy of a single trapped 88Sr+ ion clock referenced to the 5s2 S 1/2 - 4d 2 D 5/2 transition at 445 THz at the National Research Council of Canada has reached 1.2 x 10-17 over recent years. On the other hand, the stability of an atomic clock determines how long the signals from two similar clocks have to be compared to reach a given level of uncertainty. Here, we report on the improvement of the stability of NRC's 88Sr+ single ion clock by reducing the Allan deviation from 1 x 10-14 to 3 x 10-15 at 1 second averaging time. This is done by the implementation of a clear out laser that transfers the ion from the metastable state to the ground state at each cycle, followed by a state-preparation step that transfers the ion to the desired ground state magnetic sublevel of the probed transition.

  4. Reliability characteristics of microfabricated Rb mini-lamps for optical pumping in miniature atomic clocks and magnetometers

    NASA Astrophysics Data System (ADS)

    Venkatraman, Vinu; Pétremand, Yves; de Rooij, Nico; Shea, Herbert

    2013-03-01

    With the rising need for microfabricated chip-scale atomic clocks to enable high precision timekeeping in portable applications, there has been active interest in developing miniature (clocks. We reported in 2012 a first microfabricated chip-scale Rubidium dielectric barrier discharge lamp. The device's preliminary results indicated its high potential for optical pumping applications and wafer-scale batch fabrication. The chip-scale plasma light sources were observed to be robust with no obvious performance change after thousands of plasma ignitions, and with no electrode erosion from plasma discharges since the electrodes are external. However, as atomic clocks have strict lamp performance requirements including less than 0.1% sub-second optical power fluctuations, power consumption less than 20 mW and a device lifetime of at least several years, it is important to understand the long-term reliability of these Rb planar mini-lamps, and identify the operating conditions where these devices can be most reliable and stable. In this paper, we report on the reliability of such microfabricated lamps including a continuous several month run of the lamp where the optical power, electrical power consumption and temperature stability were continuously monitored. We also report on the effects of temperature, rf-power and the lamp-drive parasitics on the optical power stability and discuss steps that could be taken to further improve the device's performance and reliability.

  5. One-liter Hg ion clock for space and ground applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang; Le, Thanh; Beach, Maggie; Maleki, Lute; Tjoelker, Robert L.

    2003-01-01

    We describe the development of a small Hg ion clock suitable for space use. A small clock occupying 1-2 liters volume and producing stability of 10 to the power negative twelve, divided by square root pi would significantly advance the state of space-qualified atomic clocks. Based on recent measurements, this technology should produce long-term stability as good as 10 to the power negative fifteen.

  6. Metrological characterization of custom-designed 894.6 nm VCSELs for miniature atomic clocks.

    PubMed

    Gruet, F; Al-Samaneh, A; Kroemer, E; Bimboes, L; Miletic, D; Affolderbach, C; Wahl, D; Boudot, R; Mileti, G; Michalzik, R

    2013-03-11

    We report on the characterization and validation of custom-designed 894.6 nm vertical-cavity surface-emitting lasers (VCSELs), for use in miniature Cs atomic clocks based on coherent population trapping (CPT). The laser relative intensity noise (RIN) is measured to be 1 × 10(-11) Hz(-1) at 10 Hz Fourier frequency, for a laser power of 700 μW. The VCSEL frequency noise is 10(13) · f(-1) Hz(2)/Hz in the 10 Hz < f < 10(5) Hz range, which is in good agreement with the VCSEL’s measured fractional frequency instability (Allan deviation) of ≈ 1 × 10(-8) at 1 s, and also is consistent with the VCSEL’s typical optical linewidth of 20-25 MHz. The VCSEL bias current can be directly modulated at 4.596 GHz with a microwave power of -6 to +6 dBm to generate optical sidebands for CPT excitation. With such a VCSEL, a 1.04 kHz linewidth CPT clock resonance signal is detected in a microfabricated Cs cell filled with Ne buffer gas. These results are compatible with state-of-the-art CPT-based miniature atomic clocks exhibiting a short-term frequency instability of 2-3 × 10(-11) at τ = 1 s and few 10(-12) at τ = 10(4) s integration time.. PMID:23482148

  7. A highly miniaturized vacuum package for a trapped ion atomic clock

    NASA Astrophysics Data System (ADS)

    Schwindt, Peter D. D.; Jau, Yuan-Yu; Partner, Heather; Casias, Adrian; Wagner, Adrian R.; Moorman, Matthew; Manginell, Ronald P.; Kellogg, James R.; Prestage, John D.

    2016-05-01

    We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm3 in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, it was sealed with a copper pinch-off and was subsequently pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of 171Y b+. The fractional frequency stability of the clock was measured to be 2 × 10-11/τ1/2.

  8. A highly miniaturized vacuum package for a trapped ion atomic clock

    DOE PAGESBeta

    Schwindt, Peter D. D.; Jau, Yuan-Yu; Partner, Heather; Casias, Adrian; Wagner, Adrian R.; Moorman, Matthew; Manginell, Ronald P.; Kellogg, James R.; Prestage, John D.

    2016-05-12

    We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm3 in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, the package wasmore » sealed with a copper pinch-off and was then pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of 171Yb+. The fractional frequency stability of the clock was measured to be 2 × 10-11 / τ1/2.« less

  9. A highly miniaturized vacuum package for a trapped ion atomic clock.

    PubMed

    Schwindt, Peter D D; Jau, Yuan-Yu; Partner, Heather; Casias, Adrian; Wagner, Adrian R; Moorman, Matthew; Manginell, Ronald P; Kellogg, James R; Prestage, John D

    2016-05-01

    We report on the development of a highly miniaturized vacuum package for use in an atomic clock utilizing trapped ytterbium-171 ions. The vacuum package is approximately 1 cm(3) in size and contains a linear quadrupole RF Paul ion trap, miniature neutral Yb sources, and a non-evaporable getter pump. We describe the fabrication process for making the Yb sources and assembling the vacuum package. To prepare the vacuum package for ion trapping, it was evacuated, baked at a high temperature, and then back filled with a helium buffer gas. Once appropriate vacuum conditions were achieved in the package, it was sealed with a copper pinch-off and was subsequently pumped only by the non-evaporable getter. We demonstrated ion trapping in this vacuum package and the operation of an atomic clock, stabilizing a local oscillator to the 12.6 GHz hyperfine transition of (171)Y b(+). The fractional frequency stability of the clock was measured to be 2 × 10(-11)/τ(1/2). PMID:27250397

  10. Colloquium: Physics of optical lattice clocks

    SciTech Connect

    Derevianko, Andrei; Katori, Hidetoshi

    2011-04-01

    Recently invented and demonstrated optical lattice clocks hold great promise for improving the precision of modern time keeping. These clocks aim at the 10{sup -18} fractional accuracy, which translates into a clock that would neither lose nor gain a fraction of a second over an estimated age of the Universe. In these clocks, millions of atoms are trapped and interrogated simultaneously, dramatically improving clock stability. Here the principles of operation of these clocks are discussed and, in particular, a novel concept of magic trapping of atoms in optical lattices. Recently proposed microwave lattice clocks are also highlights and several applications that employ the optical lattice clocks as a platform for precision measurements and quantum information processing.

  11. Highly charged ions for atomic clocks and search for variation of the fine structure constant

    NASA Astrophysics Data System (ADS)

    Dzuba, V. A.; Flambaum, V. V.

    2015-11-01

    We review a number of highly charged ions which have optical transitions suitable for building extremely accurate atomic clocks. This includes ions from Hf 12+ to U 34+, which have the 4 f 12 configuration of valence electrons, the Ir 17+ ion, which has a hole in almost filled 4 f subshell, the Ho 14+, Cf 15+, Es 17+ and Es 16+ ions. Clock transitions in most of these ions are sensitive to variation of the fine structure constant, α (α = e2/hbar c). E.g., californium and einsteinium ions have largest known sensitivity to α-variation while holmium ion looks as the most suitable ion for experimental study. We study the spectra of the ions and their features relevant to the use as frequency standards.

  12. Status of the atomic fountain clock at the National Research Council of Canada

    NASA Astrophysics Data System (ADS)

    Beattie, S.; Alcock, J.; Jian, B.; Gertsvolf, M.; Bernard, J.

    2016-06-01

    Despite the rapid advances in optical frequency standards, caesium fountain clocks retain a critical role as the most accurate primary frequency standards available. At the National Research Council Canada, we are working to develop a second generation caesium fountain clock. Work is currently underway to improve several systems of FCs1, such as the laser system and microwave local oscillator, which will be incorporated into its refurbished version, FCs2. In addition, we have added an optical pumping stage which has increased the detected atom number by over a factor of six. In collaboration with the National Physical Laboratory (NPL), we are planning on replacing the physics package of FCs1. We will report on several recent improvements to FCs1, along with our progress in the development of FCs2.

  13. Low-phase-noise frequency synthesizer for the trapped atom clock on a chip.

    PubMed

    Ramirez-Martinez, Fernando; Lours, Michel; Rosenbusch, Peter; Reinhard, Friedemann; Reichel, Jakob

    2010-01-01

    We report on the realization of a 6.834-GHz synthesis chain for the trapped atom clock on a chip (TACC) that is being developed at LNE-SYRTE. The chain is based on the frequency multiplication of a 100-MHz reference signal to obtain a signal at 6.4 GHz. It uses a comb generator based on a monolithic GaAs nonlinear transmission line. This is a novelty in the fabrication of high-stability microwave synthesizers. Measurements give a low flicker phase noise of -85 dBrad(2)/Hz at 1-Hz offset frequency and a white phase noise floor < -115 dBrad(2)/Hz. Based on these results, we estimate that the performance of the synthesizer is at least one order of magnitude better than the stability goal of TACC. This ensures that the synthesizer will not be limiting the clock performance. PMID:20040431

  14. A Hertz-Linewidth Ultrastable Diode Laser System for Clock Transition Detection of Strontium Atoms

    NASA Astrophysics Data System (ADS)

    Li, Ye; Lin, Yi-Ge; Wang, Qiang; Wang, Shao-Kai; Zhao, Yang; Meng, Fei; Lin, Bai-Ke; Cao, Jian-Ping; Li, Tian-Chu; Fang, Zhan-Jun; Zang, Er-Jun

    2014-02-01

    The frequencies of two 698 nm external cavity diode lasers (ECDLs) are locked separately to two independently located ultrahigh finesse optical resonant cavities with the Pound—Drever—Hall technique. The linewidth of each ECDL is measured to be ~4.6 Hz by their beating and the fractional frequency stability below 5 × 10-15 between 1 s to 10 s averaging time. Another 698 nm laser diode is injection locked to one of the cavity-stabilized ECDLs with a fixed frequency offset for power amplification while maintaining its linewidth and frequency characteristics. The frequency drift is ~1 Hz/s measured by a femtosecond optical frequency comb based on erbium fiber. The output of the injection slave laser is delivered to the magneto-optical trap of a Sr optical clock through a 10-m-long single mode polarization maintaining fiber with an active fiber noise cancelation technique to detect the clock transition of Sr atoms.

  15. Applications of clocks and frequency standards: from the routine to tests of fundamental models

    NASA Astrophysics Data System (ADS)

    Maleki, Lute; Prestage, John

    2005-06-01

    The traditional applications of clocks and oscillators in navigation and scientific research continue to grow as new and more widespread applications emerge. Today, clocks and oscillators regulate the speed and efficiency of virtually every human endeavour ranging from the mundane to the exotic. In this paper we discuss some of the applications that require the service of high performance clocks and oscillators. In particular, we discuss space applications of clocks for navigation and scientific experiments. We also present a discussion of satellite navigation systems, especially the Global Positioning System, and comment on time dissemination over the Internet.

  16. Performance of a prototype atomic clock based on lin parallel lin coherent population trapping resonances in Rb atomic vapor

    SciTech Connect

    Mikhailov, Eugeniy E.; Horrom, Travis; Belcher, Nathan; Novikova, Irina

    2010-03-15

    We report on the performance of the first table-top prototype atomic clock based on coherent population trapping (CPT) resonances with parallel linearly polarized optical fields (lin parallel lin configuration). Our apparatus uses a vertical-cavity surface-emitting laser (VCSEL) tuned to the D{sub 1} line of {sup 87}Rb with the current modulation at the {sup 87}Rb hyperfine frequency. We demonstrate cancellation of the first-order light shift by the proper choice of rf modulation power and further improve our prototype clock stability by optimizing the parameters of the microwave lock loop. Operating in these optimal conditions, we measured a short-term fractional frequency stability (Allan deviation) 2x10{sup -11}{tau}{sup -1/2} for observation times 1 s{<=}{tau}{<=}20 s. This value is limited by large VCSEL phase noise and environmental temperature fluctuation. Further improvements in frequency stability should be possible with an apparatus designed as a dedicated lin parallel lin CPT resonance clock with environmental impacts minimized.

  17. Composite pulses in Hyper-Ramsey spectroscopy for the next generation of atomic clocks

    NASA Astrophysics Data System (ADS)

    Zanon-Willette, T.; Minissale, M.; Yudin, V. I.; Taichenachev, A. V.

    2016-06-01

    The next generation of atomic frequency standards based on an ensemble of neutral atoms or a single-ion will provide very stringent tests in metrology, applied and fundamental physics requiring a new step in very precise control of external systematic corrections. In the proceedings of the 8th Symposium on Frequency Standards and Metrology, we present a generalization of the recent Hyper-Ramsey spectroscopy with separated oscillating fields using composites pulses in order to suppress field frequency shifts induced by the interrogation laser itself. Sequences of laser pulses including specific selection of phases, frequency detunings and durations are elaborated to generate spectroscopic signals with a strong reduction of the light-shift perturbation by off resonant states. New optical clocks based on weakly allowed or completely forbidden transitions in atoms, ions, molecules and nuclei will benefit from these generalized Ramsey schemes to reach relative accuracies well below the 10-18 level.

  18. Motional dephasing of atomic clock spin waves in an optical lattice

    NASA Astrophysics Data System (ADS)

    Jenkins, S. D.; Zhang, T.; Kennedy, T. A. B.

    2012-06-01

    In a cold atomic ensemble the weak Raman scattering of an incident laser beam writes a spin-wave grating by transferring an atom between ground-level hyperfine states. These spin-waves serve as a basis for a quantum memory. For clock states, where magnetic dephasing is suppressed, thermal motion of the atoms across the spin-wave is the principal source of dephasing on the sub-millisecond timescale, limiting the quantum memory time achievable. An investigation of the role of the optical lattice in reducing motional dephasing is presented, using Monte Carlo simulations to study the influence of ensemble temperature, trap depth and differential ac Stark shifts in the case of rubidium.

  19. Automatic compensation of magnetic field for a rubidium space cold atom clock

    NASA Astrophysics Data System (ADS)

    Lin, Li; Jingwei, Ji; Wei, Ren; Xin, Zhao; Xiangkai, Peng; Jingfeng, Xiang; Desheng, Lü; Liang, Liu

    2016-07-01

    When the cold atom clock operates in microgravity around the near-earth orbit, its performance will be affected by the fluctuation of magnetic field. A strategy is proposed to suppress the fluctuation of magnetic field by additional coils, whose current is changed accordingly to compensate the magnetic fluctuation by the linear and incremental compensation. The flight model of the cold atom clock is tested in a simulated orbital magnetic environment and the magnetic field fluctuation in the Ramsey cavity is reduced from 17 nT to 2 nT, which implied the uncertainty due to the second order Zeeman shift is reduced to be less than 2×10‑16. In addition, utilizing the compensation, the magnetic field in the trapping zone can be suppressed from 7.5 μT to less than 0.3 μT to meet the magnetic field requirement of polarization gradients cooling of atoms. Project supported by the Ministry of Science and Technology of China (Grant No. 2013YQ09094304), the Youth Innovation Promotion Association, Chinese Academy of Sciences, and the National Natural Science Foundation of China (Grant Nos. 11034008 and 11274324).

  20. Optical lattice polarization effects on magnetically induced optical atomic clock transitions

    SciTech Connect

    Taichenachev, A. V.; Yudin, V. I.; Oates, C. W.

    2007-08-15

    We derive the frequency shift for a forbidden optical transition J=0{yields}J{sup '}=0 caused by the simultaneous actions of an elliptically polarized lattice field and a static magnetic field. We find that a simple configuration of lattice and magnetic fields leads to a cancellation of this shift to first order in lattice intensity and magnetic field. In this geometry, the second-order lattice intensity shift can be minimized as well by use of optimal lattice polarization. Suppression of these shifts could considerably enhance the performance of the next generation of atomic clocks.

  1. Reaching 5.0×10-13 τ -1/2 short term frequency stability of the integrating sphere cold atom clock

    NASA Astrophysics Data System (ADS)

    Liu, P.; Meng, Y. L.; Wan, J. Y.; Wang, X. M.; Wang, Y. N.; Xiao, L.; Cheng, H. D.; Liu, L.

    2016-06-01

    We present an improvement of short term frequency stability of the integrating sphere cold atom clock after increasing the intensities of clock signals and optimizing the feedback loop of the clock. A short term frequency stability of 5.0×10-13 τ -1/2 has been achieved and the limiting factors have been analyzed.

  2. Gyromagnetic factors and atomic clock constraints on the variation of fundamental constants

    SciTech Connect

    Luo Feng; Olive, Keith A.; Uzan, Jean-Philippe

    2011-11-01

    We consider the effect of the coupled variations of fundamental constants on the nucleon magnetic moment. The nucleon g-factor enters into the interpretation of the measurements of variations in the fine-structure constant, {alpha}, in both the laboratory (through atomic clock measurements) and in astrophysical systems (e.g. through measurements of the 21 cm transitions). A null result can be translated into a limit on the variation of a set of fundamental constants, that is usually reduced to {alpha}. However, in specific models, particularly unification models, changes in {alpha} are always accompanied by corresponding changes in other fundamental quantities such as the QCD scale, {Lambda}{sub QCD}. This work tracks the changes in the nucleon g-factors induced from changes in {Lambda}{sub QCD} and the light quark masses. In principle, these coupled variations can improve the bounds on the variation of {alpha} by an order of magnitude from existing atomic clock and astrophysical measurements. Unfortunately, the calculation of the dependence of g-factors on fundamental parameters is notoriously model-dependent.

  3. A Technology Demonstration Experiment for Laser Cooled Atomic Clocks in Space

    NASA Technical Reports Server (NTRS)

    Klipstein, W. M.; Kohel, J.; Seidel, D. J.; Thompson, R. J.; Maleki, L.; Gibble, K.

    2000-01-01

    We have been developing a laser-cooling apparatus for flight on the International Space Station (ISS), with the intention of demonstrating linewidths on the cesium clock transition narrower than can be realized on the ground. GLACE (the Glovebox Laser- cooled Atomic Clock Experiment) is scheduled for launch on Utilization Flight 3 (UF3) in 2002, and will be mounted in one of the ISS Glovebox platforms for an anticipated 2-3 week run. Separate flight definition projects funded at NIST and Yale by the Micro- gravity Research Division of NASA as a part of its Laser Cooling and Atomic Physics (LCAP) program will follow GLACE. Core technologies for these and other LCAP missions are being developed at JPL, with the current emphasis on developing components such as the laser and optics subsystem, and non-magnetic vacuum-compatible mechanical shutters. Significant technical challenges in developing a space qualifiable laser cooling apparatus include reducing the volume, mass, and power requirements, while increasing the ruggedness and reliability in order to both withstand typical launch conditions and achieve several months of unattended operation. This work was performed at the Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration.

  4. Improved limits on interactions of low-mass spin-0 dark matter from atomic clock spectroscopy

    NASA Astrophysics Data System (ADS)

    Stadnik, Y. V.; Flambaum, V. V.

    2016-08-01

    Low-mass (sub-eV) spin-0 dark matter particles, which form a coherently oscillating classical field ϕ =ϕ0cos(mϕt ) , can induce oscillating variations in the fundamental constants through their interactions with the standard model sector. We calculate the effects of such possible interactions, which may include the linear interaction of ϕ with the Higgs boson, on atomic and molecular transitions. Using recent atomic clock spectroscopy measurements, we derive limits on the linear interaction of ϕ with the Higgs boson, as well as its quadratic interactions with the photon and light quarks. For the linear interaction of ϕ with the Higgs boson, our derived limits improve on existing constraints by up to 2-3 orders of magnitude.

  5. Variation of Fundamental Constants from the Big Bang to Atomic Clocks:. Theory and Observations

    NASA Astrophysics Data System (ADS)

    Flambaum, V. V.; Berengut, J. C.

    2009-04-01

    Theories unifying gravity with other interactions suggest the possibility of temporal and spatial variation of the fundamental "constants" in an expanding Universe. In this review we discuss the effects of variation of the fine-structure constant and fundamental masses on measurements covering the lifespan of the Universe from a few minutes after Big Bang to the present time. Measurements give controversial results, including some hints for variation in Big Bang nucleosynthesis and quasar absorption spectra data. Furthermore there are very promising methods to search for the variation of fundamental constants by comparison of different atomic clocks. Huge enhancements of the relative variation effects happen in transitions between accidentally degenerate nuclear, atomic, and molecular energy levels.

  6. Testing for a cosmological influence on local physics using atomic and gravitational clocks

    NASA Technical Reports Server (NTRS)

    Adams, P. J.; Hellings, R. W.; Canuto, V. M.; Goldman, I.

    1983-01-01

    The existence of a possible influence of the large-scale structure of the universe on local physics is discussed. A particular realization of such an influence is discussed in terms of the behavior in time of atomic and gravitational clocks. Two natural categories of metric theories embodying a cosmic infuence exist. The first category has geodesic equations of motion in atomic units, while the second category has geodesic equations of motion in gravitational units. Equations of motion for test bodies are derived for both categories of theories in the appropriate parametrized post-Newtonian limit and are applied to the Solar System. Ranging data to the Viking lander on Mars are of sufficient precision to reveal (1) if such a cosmological influence exists at the level of Hubble's constant, and (2) which category of theories is appropriate for a descripton of the phenomenon.

  7. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    NASA Astrophysics Data System (ADS)

    François, B.; Calosso, C. E.; Abdel Hafiz, M.; Micalizio, S.; Boudot, R.

    2015-09-01

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be -109 and -141 dB rad2/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is -105 and -138 dB rad2/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10-14 for the Cs cell clock and 2 × 10-14 for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10-15 level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  8. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks.

    PubMed

    François, B; Calosso, C E; Abdel Hafiz, M; Micalizio, S; Boudot, R

    2015-09-01

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be -109 and -141 dB rad(2)/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is -105 and -138 dB rad(2)/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10(-14) for the Cs cell clock and 2 × 10(-14) for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10(-15) level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards. PMID:26429467

  9. Simple-design ultra-low phase noise microwave frequency synthesizers for high-performing Cs and Rb vapor-cell atomic clocks

    SciTech Connect

    François, B.; Calosso, C. E.; Micalizio, S.; Abdel Hafiz, M.; Boudot, R.

    2015-09-15

    We report on the development and characterization of novel 4.596 GHz and 6.834 GHz microwave frequency synthesizers devoted to be used as local oscillators in high-performance Cs and Rb vapor-cell atomic clocks. The key element of the synthesizers is a custom module that integrates a high spectral purity 100 MHz oven controlled quartz crystal oscillator frequency-multiplied to 1.6 GHz with minor excess noise. Frequency multiplication, division, and mixing stages are then implemented to generate the exact output atomic resonance frequencies. Absolute phase noise performances of the output 4.596 GHz signal are measured to be −109 and −141 dB rad{sup 2}/Hz at 100 Hz and 10 kHz Fourier frequencies, respectively. The phase noise of the 6.834 GHz signal is −105 and −138 dB rad{sup 2}/Hz at 100 Hz and 10 kHz offset frequencies, respectively. The performances of the synthesis chains contribute to the atomic clock short term fractional frequency stability at a level of 3.1 × 10{sup −14} for the Cs cell clock and 2 × 10{sup −14} for the Rb clock at 1 s averaging time. This value is comparable with the clock shot noise limit. We describe the residual phase noise measurements of key components and stages to identify the main limitations of the synthesis chains. The residual frequency stability of synthesis chains is measured to be at the 10{sup −15} level for 1 s integration time. Relevant advantages of the synthesis design, using only commercially available components, are to combine excellent phase noise performances, simple-architecture, low-cost, and to be easily customized for signal output generation at 4.596 GHz or 6.834 GHz for applications to Cs or Rb vapor-cell frequency standards.

  10. Formulation of geopotential difference determination using optical-atomic clocks onboard satellites and on ground based on Doppler cancellation system

    NASA Astrophysics Data System (ADS)

    Shen, Ziyu; Shen, Wen-Bin; Zhang, Shuangxi

    2016-08-01

    In this study, we propose an approach for determining the geopotential difference using high-frequency-stability microwave links between satellite and ground station based on Doppler cancellation system. Suppose a satellite and a ground station are equipped with precise optical-atomic clocks (OACs) and oscillators. The ground oscillator emits a signal with frequency fa towards the satellite and the satellite receiver (connected with the satellite oscillator) receives this signal with frequency fb which contains the gravitational frequency shift effect and other signals and noises. After receiving this signal, the satellite oscillator transmits and emits, respectively, two signals with frequencies fb and fc towards the ground station. Via Doppler cancellation technique, the geopotential difference between the satellite and the ground station can be determined based on gravitational frequency shift equation by a combination of these three frequencies. For arbitrary two stations on ground, based on similar procedures as described above, we may determine the geopotential difference between these two stations via a satellite. Our analysis shows that the accuracy can reach 1 m2 s- 2 based on the clocks' inaccuracy of about 10-17 (s s-1) level. Since OACs with instability around 10-18 in several hours and inaccuracy around 10-18 level have been generated in laboratory, the proposed approach may have prospective applications in geoscience, and especially, based on this approach a unified world height system could be realized with one-centimetre level accuracy in the near future.

  11. Suppression of collisional shifts via strong inter-atomic interactions in a 87Sr optical lattice clock

    NASA Astrophysics Data System (ADS)

    Martin, Michael; Swallows, Matthew; Bishof, Michael; Lin, Yige; Blatt, Sebastian; Rey, Ana Maria; Ye, Jun

    2011-05-01

    Optical lattice clocks based on ensembles of neutral atoms have the potential to operate at the highest levels of stability due to the parallel interrogation of many atoms. However, the control of systematic shifts in these systems is correspondingly difficult due to the potential of collisional shifts. Clocks based on ultracold fermionic ensembles still exhibit these density-dependent shifts due to a loss of indistinguishability during the clock excitation process, limiting clock accuracy. By tightly confining samples of ultracold fermionic 87Sr atoms in a two-dimensional optical lattice, as opposed to the conventional one-dimensional geometry, we increase the collisional interaction energy to be the largest relevant energy scale, thus entering the strongly interacting regime of clock operation. We show both theoretically and experimentally that this increase in interaction energy results in a paradoxical decrease in the collisional shift, reducing this key systematic to the 10-17 level. This work was supported by the ARO with funding from the DARPA OLE program, NIST, NSF, and AFOSR.

  12. Utilization of the Deep Space Atomic Clock for Europa Gravitational Tide Recovery

    NASA Technical Reports Server (NTRS)

    Seubert, Jill; Ely, Todd

    2015-01-01

    Estimation of Europa's gravitational tide can provide strong evidence of the existence of a subsurface liquid ocean. Due to limited close approach tracking data, a Europa flyby mission suffers strong coupling between the gravity solution quality and tracking data quantity and quality. This work explores utilizing Low Gain Antennas with the Deep Space Atomic Clock (DSAC) to provide abundant high accuracy uplink-only radiometric tracking data. DSAC's performance, expected to exhibit an Allan Deviation of less than 3e-15 at one day, provides long-term stability and accuracy on par with the Deep Space Network ground clocks, enabling one-way radiometric tracking data with accuracy equivalent to that of its two-way counterpart. The feasibility of uplink-only Doppler tracking via the coupling of LGAs and DSAC and the expected Doppler data quality are presented. Violations of the Kalman filter's linearization assumptions when state perturbations are included in the flyby analysis results in poor determination of the Europa gravitational tide parameters. B-plane targeting constraints are statistically determined, and a solution to the linearization issues via pre-flyby approach orbit determination is proposed and demonstrated.

  13. Multipolar theory of blackbody radiation shift of atomic energy levels and its implications for optical lattice clocks

    SciTech Connect

    Porsev, Sergey G.; Derevianko, Andrei

    2006-08-15

    Blackbody radiation (BBR) shifts of the {sup 3}P{sub 0}-{sup 1}S{sub 0} clock transition in the divalent atoms Mg, Ca, Sr, and Yb are evaluated. The dominant electric-dipole contributions are computed using accurate relativistic many-body techniques of atomic structure. At room temperatures, the resulting uncertainties in the E1 BBR shifts are large and substantially affect the projected 10{sup -18} fractional accuracy of the optical-lattice-based clocks. A peculiarity of these clocks is that the characteristic BBR wavelength is comparable to the {sup 3}P fine-structure intervals. To evaluate relevant M1 and E2 contributions, a theory of multipolar BBR shifts is developed. The resulting corrections, although presently masked by the uncertainties in the E1 contribution, are required at the 10{sup -18} accuracy goal.

  14. Test of relativistic time dilation with fast optical atomic clocks at different velocities

    NASA Astrophysics Data System (ADS)

    Reinhardt, Sascha; Saathoff, Guido; Buhr, Henrik; Carlson, Lars A.; Wolf, Andreas; Schwalm, Dirk; Karpuk, Sergei; Novotny, Christian; Huber, Gerhard; Zimmermann, Marcus; Holzwarth, Ronald; Udem, Thomas; Hänsch, Theodor W.; Gwinner, Gerald

    2007-12-01

    Time dilation is one of the most fascinating aspects of special relativity as it abolishes the notion of absolute time. It was first observed experimentally by Ives and Stilwell in 1938 using the Doppler effect. Here we report on a method, based on fast optical atomic clocks with large, but different Lorentz boosts, that tests relativistic time dilation with unprecedented precision. The approach combines ion storage and cooling with optical frequency counting using a frequency comb. 7Li+ ions are prepared at 6.4% and 3.0% of the speed of light in a storage ring, and their time is read with an accuracy of 2×10-10 using laser saturation spectroscopy. The comparison of the Doppler shifts yields a time dilation measurement represented by a Mansouri-Sexl parameter , consistent with special relativity. This constrains the existence of a preferred cosmological reference frame and CPT- and Lorentz-violating `new' physics beyond the standard model.

  15. Chronometric measurement of the orthometric height differences by means of atomic clocks

    NASA Astrophysics Data System (ADS)

    Kopeikin, Sergei; Mazurova, Elena; Kanushin, Vadim F.; Karpik, Alexander P.; Tolstikov, Alexander S.; Gienko, Elena G.; Goldobin, Denis N.; Kosarev, Nikolay S.; Ganagina, Irina G.; Karaush, Artem A.; Hanikova, Ekaterina A.

    2016-07-01

    We report on the experimental results of the approbation of a new physical method of determination of the potential difference of the gravity force and the orthometric heights by means of the measurement of the gravitational red shift of frequency with atomic clocks. The experiment has been performed on the territory of Altai Mountains between two geodetic stations "Shebalino" and "Seminsky" which are separated in altitude by about 850 meters. The mean value of the frequency shift caused by the change in the potential of the gravity force measured between the two geodetic stations was found to be equal to δ f/f=7.98× 10^{-14} with the dispersion being equal to σ _{f} =7.27× 10^{-15} . This difference perfectly agrees with the independent geodetic measurements of the height difference between the two stations.

  16. Compact Microwave Mercury Ion Clock for Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tu, Meirong; Chung, Sang K.; MacNeal, Paul

    2007-01-01

    We review progress in developing a small Hg ion clock for space operation based on breadboard ion-clock physics package where Hg ions are shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability approx.1-2x10(exp -13) at 1 second, averaging to 10-15 at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required or holding 1-2x10(exp -13) at 1 second. We have completed an ion clock physics package designed to withstand vibration of launch and are currently building a approx. 1 kg engineering model for test. We also discuss frequency steering software algorithms that simultaneously measure ion signal size and lamp light output, useful for long term operation and self-optimization of microwave power and return engineering data.

  17. Proceedings of the Workshop on the Scientific Applications of Clocks in Space

    NASA Technical Reports Server (NTRS)

    Maleki, Lute (Editor)

    1997-01-01

    The Workshop on Scientific Applications of Clocks in space was held to bring together scientists and technologists interested in applications of ultrastable clocks for test of fundamental theories, and for other science investigations. Time and frequency are the most precisely determined of all physical parameters, and thus are the required tools for performing the most sensitive tests of physical theories. Space affords the opportunity to make measurement, parameters inaccessible on Earth, and enables some of the most original and sensitive tests of fundamental theories. In the past few years, new developments in clock technologies have pointed to the opportunity for flying ultrastable clocks in support of science investigations of space missions. This development coincides with the new NASA paradigm for space flights, which relies on frequent, low-cost missions in place of the traditional infrequent and high-cost missions. The heightened interest in clocks in space is further advanced by new theoretical developments in various fields. For example, recent developments in certain Grand Unified Theory formalisms have vastly increased interest in fundamental tests of gravitation physics with clocks. The workshop included sessions on all related science including relativity and gravitational physics, cosmology, orbital dynamics, radio science, geodynamics, and GPS science and others, as well as a session on advanced clock technology.

  18. Direct Excitation of the Forbidden Clock Transition in Neutral {sup 174}Yb Atoms Confined to an Optical Lattice

    SciTech Connect

    Barber, Z.W.; Hoyt, C.W.; Oates, C.W.; Hollberg, L.; Taichenachev, A.V.; Yudin, V.I.

    2006-03-03

    We report direct single-laser excitation of the strictly forbidden (6s{sup 2}){sup 1}S{sub 0}{r_reversible}(6s6p){sup 3}P{sub 0} clock transition in {sup 174}Yb atoms confined to a 1D optical lattice. A small ({approx}1.2 mT) static magnetic field was used to induce a nonzero electric dipole transition probability between the clock states at 578.42 nm. Narrow resonance linewidths of 20 Hz (FWHM) with high contrast were observed, demonstrating a resonance quality factor of 2.6x10{sup 13}. The previously unknown ac Stark shift-canceling (magic) wavelength was determined to be 759.35{+-}0.02 nm. This method for using the metrologically superior even isotope can be easily implemented in current Yb and Sr lattice clocks and can create new clock possibilities in other alkaline-earth-like atoms such as Mg and Ca.

  19. Reference clock parameters for digital communications systems applications

    NASA Technical Reports Server (NTRS)

    Kartaschoff, P.

    1981-01-01

    The basic parameters relevant to the design of network timing systems describe the random and systematic time departures of the system elements, i.e., master (or reference) clocks, transmission links, and other clocks controlled over the links. The quantitative relations between these parameters were established and illustrated by means of numerical examples based on available measured data. The examples were limited to a simple PLL control system but the analysis can eventually be applied to more sophisticated systems at the cost of increased computational effort.

  20. Quantum-noise-limited interferometric measurement of atomic noise: Towards spin squeezing on the Cs clock transition

    SciTech Connect

    Oblak, Daniel; Tittel, Wolfgang; Vershovski, Anton K.; Mikkelsen, Jens K.; Soerensen, Jens L.; Petrov, Plamen G.; Garrido Alzar, Carlos L.; Polzik, Eugene S.

    2005-04-01

    We investigate theoretically and experimentally a nondestructive interferometric measurement of the state population of an ensemble of laser-cooled and trapped atoms. This study is a step toward generation of (pseudo)spin squeezing of cold atoms targeted at the improvement of the cesium clock performance beyond the limit set by the quantum projection noise of atoms. We calculate the phase shift and the quantum noise of a near-resonant optical probe pulse propagating through a cloud of cold {sup 133}Cs atoms. We analyze the figure of merit for a quantum nondemolition (QND) measurement of the collective pseudospin and show that it can be expressed simply as a product of the ensemble optical density and the pulse-integrated rate of the spontaneous emission caused by the off-resonant probe light. Based on this, we propose a protocol for the sequence of operations required to generate and utilize spin squeezing for the improved atomic clock performance via a QND measurement on the probe light. In the experimental part we demonstrate that the interferometric measurement of the atomic population can reach a sensitivity of the order of {radical}(N{sub at}) in a cloud of N{sub at} cold atoms, which is an important benchmark toward the experimental realization of the theoretically analyzed protocol.

  1. Optimization of FM spectroscopy parameters for a frequency locking loop in small scale CPT based atomic clocks.

    PubMed

    Ben-Aroya, I; Kahanov, M; Eisenstein, G

    2007-11-12

    We describe the optimization of a Frequency Locked Loop (FLL) in an atomic clock which is based on Coherent Population Trapping (CPT) in (87)Rb vapor using the D(2) transition. The FLL uses frequency modulation (FM) spectroscopy and we study the effect of FM parameters (modulation frequency and index) on the sensitivity and the signal to noise ratio of the feedback signal in the FLL. The clock which employs a small spherical glass cell containing (87)Rb atoms and a buffer gas, exhibits a short term stability of 3x10(-11)/ radicaltau. The long term relative frequency stability of the 10 MHz output is better than 10(-10) with a drift of 10(-11) per day. PMID:19550789

  2. Linearization of Schwarzschild's line element - Application to the clock paradox.

    NASA Technical Reports Server (NTRS)

    Broucke, R.

    1971-01-01

    This article studies the relativistic theory of the motion of a particle in the presence of a uniform acceleration field. The problem is introduced as a linearization of the fundamental line element of general relativity. The linearized line element is a solution of Einstein's field equations. The equations of geodesics corresponding to this line element are solved and applied to the clock paradox problem.-

  3. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock

    NASA Astrophysics Data System (ADS)

    François, B.; Calosso, C. E.; Danet, J. M.; Boudot, R.

    2014-09-01

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be -42, -100, -117 dB rad2/Hz and -129 dB rad2/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10-14 at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

  4. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock

    SciTech Connect

    François, B.; Boudot, R.; Calosso, C. E.; Danet, J. M.

    2014-09-15

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be −42, −100, −117 dB rad{sup 2}/Hz and −129 dB rad{sup 2}/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10{sup −14} at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

  5. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock.

    PubMed

    François, B; Calosso, C E; Danet, J M; Boudot, R

    2014-09-01

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be -42, -100, -117 dB rad(2)/Hz and -129 dB rad(2)/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10(-14) at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out. PMID:25273756

  6. Compact Microwave Mercury Ion Clock for Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Tu, Meirong; Chung, Sang K.; MacNeal, Paul

    2008-01-01

    We have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability approximately 1 - 2 x 10(exp -13) at 1 second, averaging to 10(exp -15) at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1 - 2 x 10(exp -13) at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly three years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow an approximately 400 C bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved.

  7. Miniaturized Mercury Ion Clock for Ultrastable Deep Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang; Lim, Lawrence; Le, Thanh

    2006-01-01

    We have recently completed a prototype ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability 2-3x10-13 at 1 second, averaging to 10-15 at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2x10-13 at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for nearly 1.5 years with no measurable degradation of ion trapping lifetimes or clock short-term performance. Because the tube is sealed, the Hg source and Neon buffer gas are held indefinitely, for the life of the tube. There is no consumption of Hg in this system unlike in a Cs beam tube where lifetime is often limited by Cs depletion.

  8. Progress on Small Mercury Ion Clock for Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang K.; Thompson, Robert J.; MacNeal, Paul

    2009-01-01

    We have recently completed a breadboard ion-clock physics package based on Hg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability approx.1-2x10-(sup 1)(sup 3) at 1 second, averaging to 10-(sup 1)? at 1 day. This development shows that H-maser quality stabilities can be produced in a small clock package, comparable in size to an ultra-stable quartz oscillator required for holding 1-2x10-(sup 1)(sup 3) at 1 second. This performance was obtained in a sealed vacuum configuration where only a getter pump was used to maintain vacuum. The vacuum tube containing the traps has now been under sealed vacuum conditions for over three years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow approx. 400 deg C bake-out to prepare for tube seal-off. This approach to the vacuum follows the methods used in flight vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved.

  9. Circadian rhythms. Atomic-scale origins of slowness in the cyanobacterial circadian clock.

    PubMed

    Abe, Jun; Hiyama, Takuya B; Mukaiyama, Atsushi; Son, Seyoung; Mori, Toshifumi; Saito, Shinji; Osako, Masato; Wolanin, Julie; Yamashita, Eiki; Kondo, Takao; Akiyama, Shuji

    2015-07-17

    Circadian clocks generate slow and ordered cellular dynamics but consist of fast-moving bio-macromolecules; consequently, the origins of the overall slowness remain unclear. We identified the adenosine triphosphate (ATP) catalytic region [adenosine triphosphatase (ATPase)] in the amino-terminal half of the clock protein KaiC as the minimal pacemaker that controls the in vivo frequency of the cyanobacterial clock. Crystal structures of the ATPase revealed that the slowness of this ATPase arises from sequestration of a lytic water molecule in an unfavorable position and coupling of ATP hydrolysis to a peptide isomerization with high activation energy. The slow ATPase is coupled with another ATPase catalyzing autodephosphorylation in the carboxyl-terminal half of KaiC, yielding the circadian response frequency of intermolecular interactions with other clock-related proteins that influences the transcription and translation cycle. PMID:26113637

  10. Atomic clocks based on extened-cavity diode laser in multimode operation

    NASA Astrophysics Data System (ADS)

    Yim, Sin; Cho, D.

    2011-05-01

    We demonstrated the possibilities to develope an atomic clock based on coherent population trapping (CPT) without using a local oscillator and a modulator. Instead of using a modulator, we use two modes from a single extended-cavity diode laser in multimode operation. Two different types of feedback system are applied to stabilize a difference frequency between the two modes and eliminate the need for an extra frequency modulation. In the first type, we employ an electronic feedback using dispersion of the CPT resonance as an error signal. The two modes are phase locked with reference to a dispersion signal from a CPT resonance of 85Rb at 3.036 GHz ground hyperfine splitting. We use D1 transition at 794.8 nm with lin ⊥lin polarizations to obtain large-contrast CPT signal. Allan deviation of the beat frequency between the two modes is 1 ×10-10 at 200-s integration time. In the second type, we employ optoelectronic feedback to construct an opto-electronic oscillator (OEO). In an OEO, the beating signal between two modes is recovered by a fast photodiode, and its output is amplified and fed back to the laser diode by using a direct modulation of an injection current. When the OEO loop is closed, oscillation frequency depends on variations of the loop length. In order to stabilize an OEO loop length and thereby its oscillation frequency, CPT cell is inserted to play a role of microwave band pass filter. Allan deviation of the CPT-stabilized OEO is 2 ×10-10 at 100-s integration time.

  11. N -atom collective-state atomic clock with √{N }-fold increase in effective frequency and √{N }-fold reduction in fringe width

    NASA Astrophysics Data System (ADS)

    Kim, May E.; Sarkar, Resham; Fang, Renpeng; Shahriar, Selim M.

    2015-06-01

    We describe a collective state atomic clock (COSAC) with Ramsey fringes narrowed by a factor of √{N } compared to a conventional clock—N being the number of noninteracting atoms—without violating the uncertainty relation. This narrowing is explained as being due to interferences among the collective states, representing an effective √{N }-fold increase in the clock frequency, without entanglement. We discuss the experimental inhomogeneities that affect the signal and show that experimental parameters can be adjusted to produce a near ideal signal. The detection process collects fluorescence through stimulated Raman scattering of Stokes photons, which emits photons predominantly in the direction of the probe beam for a high enough optical density. By using a null measurement scheme, in which detection of zero photons corresponds to the system being in a single collective state, we detect the population in a collective state of interest. The quantum and classical noise of the ideal COSAC is still limited by the standard quantum limit and performs only as well as the conventional clock. However, when detection efficiency and collection efficiency are taken into account, the detection scheme of the COSAC increases the quantum efficiency of detection significantly in comparison to a typical conventional clock employing fluorescence detection, yielding a net improvement in stability by as much as a factor of 10.

  12. Compact Microwave Mercury Ion Clock for Deep-Space Applications

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang K.; Lim, Lawrence; Matevosian, Annond

    2007-01-01

    We have recently completed a breadboard ion-dock physics package based on Kg ions shuttled between a quadrupole and a 16-pole rf trap. With this architecture we have demonstrated short-term stability -1-2xl0-13 at 1 second, averaging to 10-15 at 1 day. This development shows that 8- maser quality stabilities can be produced in a small clock package, comparable in size to an oItra-stable quartz oscillator required for holding 1-2xl0-13 at 1 second. This performance was obtained in a sealed vacuum configuration where only agetter pump was used to maintain vacuum. The vacuum tube containing the traps has now been onder sealed vacuum conditions for nearly two years with no measurable degradation of ion trapping lifetimes or clock short-term performance. We have fabricated the vacuum tube, ion trap and UV windows from materials that will allow a - 400 C tube bake-out to prepare for tube sealoff. This approach to the vacuum follows the methods used in mght vacuum tube electronics, such as flight TWTA's where tube operation lifetime and shelf life of up to 15 years is achieved. We use neon as a buffer gas with 2-3 times less pressure induced frequency pulling than helium and, being heavier, negligable diffusion losses will occur over the operation lifetime.

  13. Rydberg Spectroscopy in an Optical Lattice: Blackbody Thermometry for Atomic Clocks

    SciTech Connect

    Ovsiannikov, Vitali D.; Derevianko, Andrei; Gibble, Kurt

    2011-08-26

    We show that optical spectroscopy of Rydberg states can provide accurate in situ thermometry at room temperature. Transitions from a metastable state to Rydberg states with principal quantum numbers of 25-30 have 200 times larger fractional frequency sensitivities to blackbody radiation than the strontium clock transition. We demonstrate that magic-wavelength lattices exist for both strontium and ytterbium transitions between the metastable and Rydberg states. Frequency measurements of Rydberg transitions with 10{sup -16} accuracy provide 10 mK resolution and yield a blackbody uncertainty for the clock transition of 10{sup -18}.

  14. A compact laser head with high-frequency stability for Rb atomic clocks and optical instrumentation

    SciTech Connect

    Affolderbach, Christoph; Mileti, Gaetano

    2005-07-15

    We present a compact and frequency-stabilized laser head based on an extended-cavity diode laser. The laser head occupies a volume of 200 cm{sup 3} and includes frequency stabilization to Doppler-free saturated absorption resonances on the hyperfine components of the {sup 87}Rb D{sub 2} lines at 780 nm, obtained from a simple and compact spectroscopic setup using a 2 cm{sup 3} vapor cell. The measured frequency stability is {<=}2x10{sup -12} over integration times from 1 s to 1 day and shows the potential to reach 2x10{sup -13} over 10{sup 2}-10{sup 5} s. Compact laser sources with these performances are of great interest for applications in gas-cell atomic frequency standards, atomic magnetometers, interferometers and other instruments requiring stable and narrow-band optical sources.

  15. Design and implementation of fast bipolar clock drivers for CCD imaging systems in space applications

    NASA Astrophysics Data System (ADS)

    Jayarajan, Jayesh; Kumar, Nishant; Verma, Amarnath; Thaker, Ramkrishna

    2016-05-01

    Drive electronics for generating fast, bipolar clocks, which can drive capacitive loads of the order of 5-10nF are indispensable for present day Charge Coupled Devices (CCDs). Design of these high speed bipolar clocks is challenging because of the capacitive loads that have to be driven and a strict constraint on the rise and fall times. Designing drive electronics circuits for space applications becomes even more challenging due to limited number of available discrete devices, which can survive in the harsh radiation prone space environment. This paper presents the design, simulations and test results of a set of such high speed, bipolar clock drivers. The design has been tested under a thermal cycle of -15 deg C to +55 deg C under vacuum conditions and has been designed using radiation hardened components. The test results show that the design meets the stringent rise/fall time requirements of 50+/-10ns for Multiple Vertical CCD (VCCD) clocks and 20+/-5ns for Horizontal CCD (HCCD) clocks with sufficient design margins across full temperature range, with a pixel readout rate of 6.6MHz. The full design has been realized in flexi-rigid PCB with package volume of 140x160x50 mm3.

  16. Interim results from the characterization testing of the Engineering Development (EDM) rubidium clocks for satellite applications

    NASA Technical Reports Server (NTRS)

    Powers, Edward D., Jr.; Danzy, Fredrick

    1990-01-01

    Some interim results from the environmental testing program to evaluate the Engineering Design Model (EDM) of the EG and G Spaceborne Rubidium Clock are presented. This effort is in support of the Global Positioning System (GPS) BLOCK IIR program and is intended to characterize the performance of EG and G design for BLOCK IIR satellite applications. Two EG and G EDM units are currently under test at NRL's Clock Test Facility to measure the long-term frequency stability, drift, and frequency versus temperature characteristics.

  17. Accuracy budget of the 88Sr optical atomic clocks at KL FAMO

    NASA Astrophysics Data System (ADS)

    Radzewicz, Czesław; Bober, Marcin; Morzyński, Piotr; Cygan, Agata; Lisak, Daniel; Bartoszek-Bober, Dobrosława; Masłowski, Piotr; Ablewski, Piotr; Zachorowski, Jerzy; Gawlik, Wojciech; Ciuryło, Roman; Zawada, Michał

    2016-08-01

    This paper presents a detailed accuracy budget of two independent strontium optical lattice clocks at the National Laboratory FAMO (KL FAMO) probed with a single shared ultra-narrow laser. The combined instability of the two frequency standards was 7× {10}-17 after 105s of averaging.

  18. Detection of ultrahigh resonance contrast in vapor-cell atomic clocks.

    PubMed

    Lin, Jinda; Deng, Jianliao; Ma, Yisheng; He, Huijuan; Wang, Yuzhu

    2012-12-15

    We propose and demonstrate a novel detection scheme of clock signals and obtain an ultrahigh resonance contrast up to 90%, which leads to the remarkable improvement of the precision of the signal-to-noise ratio. The frequency stability in terms of Allan deviation of the proposed detection scheme is improved by an order of magnitude under equivalent conditions. PMID:23257996

  19. Innovation and reliability of atomic standards for PTTI applications

    NASA Technical Reports Server (NTRS)

    Kern, R.

    1981-01-01

    Innovation and reliability in hyperfine frequency standards and clock systems are discussed. Hyperfine standards are defined as those precision frequency sources and clocks which use a hyperfine atomic transition for frequency control and which have realized significant commercial production and acceptance (cesium, hydrogen, and rubidium atoms). References to other systems such as thallium and ammonia are excluded since these atomic standards have not been commercially exploited in this country.

  20. ECL gate array with integrated PLL-based clock recovery and synthesis for high-speed data and telecom applications

    NASA Astrophysics Data System (ADS)

    Rosky, David S.; Coy, Bruce H.; Friedmann, Marc D.

    1992-03-01

    A 2500 gate mixed signal gate array has been developed that integrates custom PLL-based clock recovery and clock synthesis functions with 2500 gates of configurable logic cells to provide a single chip solution for 200 - 1244 MHz fiber based digital interface applications. By customizing the digital logic cells, any of the popular telecom and datacom standards may be implemented.

  1. Ab initio calculations of external-field shifts of the 661-nm quadrupolar clock transition in neutral Ag atoms

    SciTech Connect

    Topcu, Suat; Nasser, Jamil; Daku, Latevi Max Lawson; Fritzsche, Stephan

    2006-04-15

    Frequency shifts of the Ag I 4d{sup 10}5s {sup 2}S{sub 1/2}(F=0,M{sub F}=0) to 4d{sup 9}5s{sup 2} {sup 2}D{sub 5/2}(F{sup '}=2,M{sub F{sup '}}=0) electric-quadrupole transition at 330.6 nm due to external fields are calculated using multiconfigurational self-consistent field methods. As this forbidden transition is free from first order Doppler and Zeeman effects, it is under investigation for the realization of an atomic optical clock. The calculated perturbations are the light shift, the blackbody frequency shift, and the quadratic Zeeman shift. Results show that a total uncertainty of 10{sup -18} could be reach without confining the atoms in a Lamb-Dicke regime in an optical lattice.

  2. A CPT-based Cs vapor cell atomic clock with a short-term fractional frequency stability of 3 x 10-13 τ-1/2

    NASA Astrophysics Data System (ADS)

    Abdel Hafiz, Moustafa; Liu, Xiaochi; Guérandel, Stéphane; De Clercq, Emeric; Boudot, Rodolphe

    2016-06-01

    This article reports on the development and short-term fractional frequency stability of a continuous-regime (CW) Cs vapor cell atomic clock based on coherent population trapping (CPT). The push-pull optical pumping technique is used to increase the number of atoms that participate to the clock transition, yielding a typical CPT resonance contrast of 25% for a CPT linewidth of about 450 Hz. The clock short-term fractional frequency stability is measured to be 3 x 10-13 τ-1/2 up to 100 seconds averaging time, in correct agreement with the signal-to-noise ratio limit. The mid-term frequency stability results are currently mainly limited by laser power effects. The detection of high-contrast narrow Raman-Ramsey fringes is demonstrated with this setup by making the atoms interact with a light pulse sequence.

  3. Editorial: Focus on Atom Optics and its Applications

    NASA Astrophysics Data System (ADS)

    Schmidt-Kaler, F.; Pfau, T.; Schmelcher, P.; Schleich, W.

    2010-06-01

    Atom optics employs the modern techniques of quantum optics and laser cooling to enable applications which often outperform current standard technologies. Atomic matter wave interferometers allow for ultra-precise sensors; metrology and clocks are pushed to an extraordinary accuracy of 17 digits using single atoms. Miniaturization and integration are driven forward for both atomic clocks and atom optical circuits. With the miniaturization of information-storage and -processing devices, the scale of single atoms is approached in solid state devices, where the laws of quantum physics lead to novel, advantageous features and functionalities. An upcoming branch of atom optics is the control of single atoms, potentially allowing solid state devices to be built atom by atom; some of which would be applicable in future quantum information processing devices. Selective manipulation of individual atoms also enables trace analysis of extremely rare isotopes. Additionally, sources of neutral atoms with high brightness are being developed and, if combined with photo ionization, even novel focused ion beam sources are within reach. Ultracold chemistry is fertilized by atomic techniques, when reactions of chemical constituents are investigated between ions, atoms, molecules, trapped or aligned in designed fields and cooled to ultra-low temperatures such that the reaction kinetics can be studied in a completely state-resolved manner. Focus on Atom Optics and its Applications Contents Sensitive gravity-gradiometry with atom interferometry: progress towards an improved determination of the gravitational constant F Sorrentino, Y-H Lien, G Rosi, L Cacciapuoti, M Prevedelli and G M Tino A single-atom detector integrated on an atom chip: fabrication, characterization and application D Heine, W Rohringer, D Fischer, M Wilzbach, T Raub, S Loziczky, XiYuan Liu, S Groth, B Hessmo and J Schmiedmayer Interaction of a propagating guided matter wave with a localized potential G L Gattobigio, A

  4. Ytterbium in quantum gases and atomic clocks: van der Waals interactions and blackbody shifts.

    PubMed

    Safronova, M S; Porsev, S G; Clark, Charles W

    2012-12-01

    We evaluated the C(6) coefficients of Yb-Yb, Yb-alkali, and Yb-group II van der Waals interactions with 2% uncertainty. The only existing experimental result for such quantities is for the Yb-Yb dimer. Our value, C(6)=1929(39) a.u., is in excellent agreement with the recent experimental determination of 1932(35) a.u. We have also developed a new approach for the calculation of the dynamic correction to the blackbody radiation shift. We have calculated this quantity for the Yb 6s(2) (1)S(0)-6s6p (3)P(0)(o) clock transition with 3.5% uncertainty. This reduces the fractional uncertainty due to the blackbody radiation shift in the Yb optical clock at 300 K to the 10(-18) level. PMID:23368178

  5. Selection and amplification of a single optical frequency comb mode for laser cooling of the strontium atoms in an optical clock

    SciTech Connect

    Liu, Hui; Yin, Mojuan; Kong, Dehuan; Xu, Qinfang; Zhang, Shougang; Chang, Hong

    2015-10-12

    In this paper, we report on the active filtering and amplification of a single mode from an optical femtosecond laser comb with mode spacing of 250 MHz by optical injection of two external-cavity diode lasers operating in cascade to build a narrow linewidth laser for laser cooling of the strontium atoms in an optical lattice clock. Despite the low injection of individual comb mode of approximately 50 nW, a single comb line at 689 nm could be filtered and amplified to reach as high as 10 mW with 37 dB side mode suppression and a linewidth of 240 Hz. This method could be applied over a broad spectral band to build narrow linewidth lasers for various applications.

  6. Cesium clocks keep the world on time

    SciTech Connect

    Hellwig, H.

    1985-09-01

    The development of timekeeping systems based on the natural resonance of cesium atoms is reviewed. The design of a typical cesium clock using a frequency lock servo is described. Some common applications of cesium beam frequency and time reference systems are discussed, including Navstar GPS navigation referencing; military satellite communications; and measurements of relative gravitational effects. The possibility of increasing timekeeping accuracies using improved cesium clock designs is evaluated.

  7. An analytic technique for statistically modeling random atomic clock errors in estimation

    NASA Technical Reports Server (NTRS)

    Fell, P. J.

    1981-01-01

    Minimum variance estimation requires that the statistics of random observation errors be modeled properly. If measurements are derived through the use of atomic frequency standards, then one source of error affecting the observable is random fluctuation in frequency. This is the case, for example, with range and integrated Doppler measurements from satellites of the Global Positioning and baseline determination for geodynamic applications. An analytic method is presented which approximates the statistics of this random process. The procedure starts with a model of the Allan variance for a particular oscillator and develops the statistics of range and integrated Doppler measurements. A series of five first order Markov processes is used to approximate the power spectral density obtained from the Allan variance.

  8. ac Stark shift measurements of the clock transition in cold Cs atoms: Scalar and tensor light shifts of the D2 transition

    NASA Astrophysics Data System (ADS)

    Costanzo, G. A.; Micalizio, S.; Godone, A.; Camparo, J. C.; Levi, F.

    2016-06-01

    The ac Stark shift, or light shift, is a physical phenomenon that plays a fundamental role in many applications ranging from basic atomic physics to applied quantum electronics. Here, we discuss experiments testing light-shift theory in a cold-atom cesium fountain clock for the Cs D2 transition (i.e., 6 2S1 /2→6 2P3 /2 at 852 nm). Cold-atom fountains represent a nearly ideal system for the study of light shifts: (1) The atoms can be perturbed by a field of arbitrary character (e.g., coherent field or nonclassical field); (2) there are no trapping fields to complicate data interpretation; (3) the probed atoms are essentially motionless in their center-of-mass reference frame, T ˜ 1 μK; and (4) the atoms are in an essentially collisionless environment. Moreover, in the present work the resolution of the Cs excited-state hyperfine splittings implies that the D2 ac Stark shift contains a nonzero tensor polarizability contribution, which does not appear in vapor phase experiments due to Doppler broadening. Here, we test the linearity of the ac Stark shift with field intensity, and measure the light shift as a function of field frequency, generating a "light-shift curve." We have improved on the previous best test of theory by a factor of 2, and after subtracting the theoretical scalar light shift from the experimental light-shift curves, we have isolated and tested the tensor light shift for an alkali D2 transition.

  9. Editorial: Focus on Atom Optics and its Applications

    NASA Astrophysics Data System (ADS)

    Schmidt-Kaler, F.; Pfau, T.; Schmelcher, P.; Schleich, W.

    2010-06-01

    Atom optics employs the modern techniques of quantum optics and laser cooling to enable applications which often outperform current standard technologies. Atomic matter wave interferometers allow for ultra-precise sensors; metrology and clocks are pushed to an extraordinary accuracy of 17 digits using single atoms. Miniaturization and integration are driven forward for both atomic clocks and atom optical circuits. With the miniaturization of information-storage and -processing devices, the scale of single atoms is approached in solid state devices, where the laws of quantum physics lead to novel, advantageous features and functionalities. An upcoming branch of atom optics is the control of single atoms, potentially allowing solid state devices to be built atom by atom; some of which would be applicable in future quantum information processing devices. Selective manipulation of individual atoms also enables trace analysis of extremely rare isotopes. Additionally, sources of neutral atoms with high brightness are being developed and, if combined with photo ionization, even novel focused ion beam sources are within reach. Ultracold chemistry is fertilized by atomic techniques, when reactions of chemical constituents are investigated between ions, atoms, molecules, trapped or aligned in designed fields and cooled to ultra-low temperatures such that the reaction kinetics can be studied in a completely state-resolved manner. Focus on Atom Optics and its Applications Contents Sensitive gravity-gradiometry with atom interferometry: progress towards an improved determination of the gravitational constant F Sorrentino, Y-H Lien, G Rosi, L Cacciapuoti, M Prevedelli and G M Tino A single-atom detector integrated on an atom chip: fabrication, characterization and application D Heine, W Rohringer, D Fischer, M Wilzbach, T Raub, S Loziczky, XiYuan Liu, S Groth, B Hessmo and J Schmiedmayer Interaction of a propagating guided matter wave with a localized potential G L Gattobigio, A

  10. GPS.DM Observatory: Search for Dark Matter and Exotic Physics with Atomic Clocks and GPS Constellation

    NASA Astrophysics Data System (ADS)

    Roberts, Benjamin; Blewitt, Geoffrey; Derevianko, Andrei; Lundholm, Nathan; Pospelov, Maxim; Rollings, Alex; Sherman, Jeff; GPS. DM Collaboration

    2016-05-01

    Despite the overwhelming cosmological evidence for the existence of dark matter, and the considerable effort of the scientific community over decades, there is no evidence for dark matter in terrestrial experiments. The GPS.DM observatory uses the existing GPS constellation as a 50,000 km-aperture sensor array, analyzing the satellite and terrestrial atomic clock data for exotic physics signatures. In particular, the collaboration searches for evidence of transient variations of fundamental constants correlated with the Earth's galactic motion through the dark matter halo. This type of search is particularly sensitive to exotic forms of dark matter, such as topological defects. We will present an update on the search. Supported by the NSF.

  11. Compact Yb+ optical atomic clock project: design principle and current status

    NASA Astrophysics Data System (ADS)

    Lacroûte, Clément; Souidi, Maël; Bourgeois, Pierre-Yves; Millo, Jacques; Saleh, Khaldoun; Bigler, Emmanuel; Boudot, Rodolphe; Giordano, Vincent; Kersalé, Yann

    2016-06-01

    We present the design of a compact optical clock based on the 2 S 1/2→2 D 3/2 435.5 nm transition in 171 Yb+. The ion trap will be based on a micro-fabricated circuit, with surface electrodes generating a trapping potential to localize a single Yb ion a few hundred μm from the electrodes. We present our trap design as well as simulations of the resulting trapping pseudo-potential. We also present a compact, multi-channel wavelength meter that will permit the frequency stabilization of the cooling, repumping and clear-out lasers at 369.5 nm, 935.2 nm and 638.6 nm needed to cool the ion. We use this wavelength meter to characterize and stabilize the frequency of extended cavity diode lasers at 369.5 nm and 638.6 nm.

  12. Military applications of high-accuracy frequency standards and clocks

    NASA Astrophysics Data System (ADS)

    Vig, John R.

    1993-08-01

    Frequency control and timing devices are essential components in modern military electronics systems. Reviewed in this paper are the applications of these devices, and the manner in which the stability and accuracy of these devices impact the performance of military communication, navigation, surveillance, electronic warfare, missile guidance, and identification-friend-or-foe systems.

  13. First nuclear clock?

    NASA Astrophysics Data System (ADS)

    2016-06-01

    A nuclear clock that is more precise than any atomic clock available today could soon be a reality after physicists in Germany detected a crucial low-energy transition in the thorium-229 nucleus, which could be used to create a new frequency standard.

  14. Coherent population trapping resonances in Cs-Ne vapor microcells for miniature clocks applications

    SciTech Connect

    Boudot, R.; Dziuban, P.; Hasegawa, M.; Chutani, R. K.; Galliou, S.; Giordano, V.; Gorecki, C.

    2011-01-01

    We report the characterization of dark line resonances observed in Cs vapor microcells filled with a unique neon (Ne) buffer gas. The impact on the coherent population trapping (CPT) resonance of some critical external parameters such as laser intensity, cell temperature, and microwave power is studied. We show the suppression of the first-order light shift by proper choice of the microwave power. The temperature dependence of the Cs ground state hyperfine resonance frequency is shown to be canceled in the 77-80 deg. C range for various Ne buffer gas pressures. The necessity to adjust the Ne buffer gas pressure or the cell dimensions to optimize the CPT signal height at the frequency inversion temperature is pointed out. Based on such Cs-Ne microcells, we preliminary demonstrate a 852 nm vertical cavity surface emitted laser (VCSEL)-modulated based CPT atomic clock exhibiting a short term fractional frequency instability {sigma}{sub y}({tau})=1.5x10{sup -10{tau}-1/2} until 30 s. These results, similar to those published in the literature by others groups, prove the potential of our original microcell technology in view of the development of high-performance chip scale atomic clocks.

  15. Relativistic effects of the rotation of the earth on remote clock synchronization

    NASA Technical Reports Server (NTRS)

    Reinhardt, V.

    1974-01-01

    A treatment is given of relativistic clock synchronization effects due to the rotation of the earth. Unlike other approaches, the point of view of an earth fixed coordinate system is used which offers insight to many problems. An attempt is made to give the reader an intuitive grasp of the subject as well as to provide formulae for his use. Specific applications to global timekeeping, navigation, VLBI, relativistic clock experiments, and satellite clock synchronization are discussed. The question of whether atomic clocks are ideal clocks is also treated.

  16. Single-Ion Atomic Clock with 3 ×10-18 Systematic Uncertainty

    NASA Astrophysics Data System (ADS)

    Huntemann, N.; Sanner, C.; Lipphardt, B.; Tamm, Chr.; Peik, E.

    2016-02-01

    We experimentally investigate an optical frequency standard based on the 2S1/2 (F =0 )→ 2F7/2 (F =3 ) electric octupole (E 3 ) transition of a single trapped 171Yb+ ion. For the spectroscopy of this strongly forbidden transition, we utilize a Ramsey-type excitation scheme that provides immunity to probe-induced frequency shifts. The cancellation of these shifts is controlled by interleaved single-pulse Rabi spectroscopy, which reduces the related relative frequency uncertainty to 1.1 ×10-18. To determine the frequency shift due to thermal radiation emitted by the ion's environment, we measure the static scalar differential polarizability of the E 3 transition as 0.888 (16 )×10-40 J m2/V2 and a dynamic correction η (300 K )=-0.0015 (7 ) . This reduces the uncertainty due to thermal radiation to 1.8 ×10-18. The residual motion of the ion yields the largest contribution (2.1 ×10-18 ) to the total systematic relative uncertainty of the clock of 3.2 ×10-18.

  17. Optical clocks and their contribution to gravity modeling

    NASA Astrophysics Data System (ADS)

    Naeimi, Mohammad; Mohamadhosseini, Babak; Hatami, Mohsen

    2016-04-01

    Optical clocks, as one of the latest achievements in atomic and molecular physics, have applications more than timing, due to their accuracy and stability. In general relativity, gravitational potential differences in space and time, cause frequency difference in optical clocks. Hence, ultra precise optical clocks can be used as a tool to observe potential differences and consequently as a new gravimetry technique. In this contribution, we investigate the latest optical clocks based on atomic transition in Al+ and derive a simple equation for frequency change related to geo-potential differences. Moreover, we consider the capability of optical clocks for gravity modeling in combination with other gravity observations. Finally, the possibility to detect potential changes in geo-dynamically active zones, such as East-Asia and the requirements for such studies are discussed.

  18. Improved limit on a temporal variation of mp/me from comparisons of Yb+ and Cs atomic clocks.

    PubMed

    Huntemann, N; Lipphardt, B; Tamm, Chr; Gerginov, V; Weyers, S; Peik, E

    2014-11-21

    Accurate measurements of different transition frequencies between atomic levels of the electronic and hyperfine structure over time are used to investigate temporal variations of the fine structure constant α and the proton-to-electron mass ratio μ. We measure the frequency of the (2)S1/2→(2)F7/2 electric octupole (E3) transition in (171)Yb(+) against two caesium fountain clocks as f(E3)=642,121,496,772,645.36  Hz with an improved fractional uncertainty of 3.9×10(-16). This transition frequency shows a strong sensitivity to changes of α. Together with a number of previous and recent measurements of the (2)S1/2→(2)D3/2 electric quadrupole transition in (171)Yb(+) and with data from other elements, a least-squares analysis yields (1/α)(dα/dt)=-0.20(20)×10(-16)/yr and (1/μ)(dμ/dt)=-0.5(1.6)×10(-16)/yr, confirming a previous limit on dα/dt and providing the most stringent limit on dμ/dt from laboratory experiments. PMID:25479483

  19. Short-scale atomic clock based on the quantum magnetometers system

    NASA Astrophysics Data System (ADS)

    Ermak, S. V.; Sagitov, E. A.; Smolin, R. V.; Semenov, V. V.

    2016-03-01

    The experimental results of dependence of Allan variance as averaging time for system of two quantum magnetometers with laser pumping of the alkaline atoms are presented. Also the role of different components of luminous frequency shift of a radio optical resonance in case of an optimum operation mode of quantum magnetometers in such system is noted. It is shown that the effect of compensation of luminous shift components allows to reduce Allan variance in times of averaging more, than hundreds of seconds in comparison with the quantum standard of frequency on 0-0 transition.

  20. Enhanced sensitivity to the fine-structure-constant variation in the Th IV atomic clock transition

    SciTech Connect

    Flambaum, V. V.; Porsev, S. G.

    2009-12-15

    Our calculations have shown that the 5f{sub 5/2}-7s{sub 1/2} 23 131 cm{sup -1} transition from the ground state in the ion Th{sup 3+} is very sensitive to the temporal variation of the fine-structure constant alpha=e{sup 2}/(Planck constant/2pi)c (q=-75 300 cm{sup -1}). The line is very narrow, the ion has been trapped and laser cooled, and the positive shifter line 5f{sub 5/2}-5f{sub 7/2} 4325 cm{sup -1} (q=+2900 cm{sup -1}) may be used as a reference. A comparison may also be made with a positive shifter in another atom or ion. This makes Th{sup 3+} a good candidate to search for the alpha variation.

  1. Comparison of mode estimation methods and application in molecular clock analysis

    NASA Technical Reports Server (NTRS)

    Hedges, S. Blair; Shah, Prachi

    2003-01-01

    BACKGROUND: Distributions of time estimates in molecular clock studies are sometimes skewed or contain outliers. In those cases, the mode is a better estimator of the overall time of divergence than the mean or median. However, different methods are available for estimating the mode. We compared these methods in simulations to determine their strengths and weaknesses and further assessed their performance when applied to real data sets from a molecular clock study. RESULTS: We found that the half-range mode and robust parametric mode methods have a lower bias than other mode methods under a diversity of conditions. However, the half-range mode suffers from a relatively high variance and the robust parametric mode is more susceptible to bias by outliers. We determined that bootstrapping reduces the variance of both mode estimators. Application of the different methods to real data sets yielded results that were concordant with the simulations. CONCLUSION: Because the half-range mode is a simple and fast method, and produced less bias overall in our simulations, we recommend the bootstrapped version of it as a general-purpose mode estimator and suggest a bootstrap method for obtaining the standard error and 95% confidence interval of the mode.

  2. A quantum network of clocks

    NASA Astrophysics Data System (ADS)

    Komar, Peter; Kessler, Eric; Bishof, Michael; Jiang, Liang; Sorensen, Anders; Ye, Jun; Lukin, Mikhail

    2014-05-01

    Shared timing information constitutes a key resource for positioning and navigation with a direct correspondence between timing accuracy and precision in applications such as the Global Positioning System (GPS). By combining precision metrology and quantum networks, we propose here a quantum, cooperative protocol for the operation of a network consisting of geographically remote optical atomic clocks. Using non-local entangled states, we demonstrate an optimal utilization of the global network resources, and show that such a network can be operated near the fundamental limit set by quantum theory yielding an ultra-precise clock signal. Furthermore, the internal structure of the network, combined with basic techniques from quantum communication, guarantees security both from internal and external threats. Realization of such a global quantum network of clocks may allow construction of a real-time single international time scale (world clock) with unprecedented stability and accuracy. See also: Komar et al. arXiv:1310.6045 (2013) and Kessler et al. arXiv:1310.6043 (2013).

  3. Microwave Cavity Clocks On Space Station

    NASA Technical Reports Server (NTRS)

    Lipa, J. a.; Nissen, J. A.; Wang, S.; Stricker, D. A.; Avaloff, D.

    2003-01-01

    We describe the status of a microwave cavity clock experiment to perform improved tests of Local Position Invariance and Lorentz Invariance on the International Space Station in conjunction with atomic clocks. Significant improvements over present bounds are expected in both cases. The oscillators can also be used to enhance the performance of atomic clocks at short time scales for other experiments.

  4. Applications of Bayesian filtering in wireless networks: Clock synchronization, localization, and RF tomography

    NASA Astrophysics Data System (ADS)

    Hamilton, Benjamin Russell

    In this work, we investigate the application of Bayesian filtering techniques such as Kalman Filtering and Particle filtering to the problems of network time synchronization, self-localization and radio-frequency (RF) tomography in wireless networks. Networks of large numbers of small, cheap, mobile wireless devices have shown enormous potential in applications ranging from intrusion detection to environmental monitoring. These applications require the devices to have accurate time and position estimates, however traditional techniques may not be available. Additionally RF tomography offers a new paradigm to sense the network environment and could greatly enhance existing network capabilities. While there are some existing works addressing these problems, they all suffer from limitations. Current time synchronization methods are not energy efficient on small wireless devices with low quality oscillators. Existing localization methods do not consider additional sources of information available to nodes in the network such as measurements from accelerometers or models of the shadowing environment in the network. RF tomography has only been examined briefly in such networks, and current algorithms can not handle node mobility and rely on shadowing models that have not been experimentally verified. We address the time synchronization problem by analyzing the characteristics of the clocks in small wireless devices, developing a model for it, and then applying a Kalman filter to track both clock offset and skew. In our investigation into RF tomography, we present a method using a Kalman filter which jointly estimates and tracks static and dynamic objects in the environment. We also use channel measurements collected from a field test of our RF tomography testbed to compare RF shadowing models. For the localization problem, we present two algorithms incorporating additional information for improved localization: one based on a distributed extended Kalman filter that

  5. Timing in the NOvA detectors with atomic clock based time transfers between Fermilab, the Soudan mine and the NOvA Far detector

    NASA Astrophysics Data System (ADS)

    Norman, A.; Niner, E.; Habig, A.

    2015-12-01

    The NOvA experiment uses a GPS based timing system both to internally synchronize the readout of the DAQ components and to establish an absolute wall clock reference which can be used to link the Fermilab accelerator complex with the neutrino flux that crosses the NOvA detectors. We describe the methods that were used during the commissioning of the NOvA DAQ and Timing systems to establish the synchronization between the Fermilab beam and the NOvA far detector. We present how high precision atomic clocks were trained and transported between the MINOS and NOvA detectors during a Northern Minnesota blizzard to validate the absolute time offsets of the experiments and make the first observation of beam neutrinos in the NOvA far detector.

  6. Optical clock transition in a rare-earth-ion-doped crystal: coherence lifetime extension for quantum storage applications

    NASA Astrophysics Data System (ADS)

    Tongning, Robert-Christopher; Chanelière, Thierry; Le Gouët, Jean-Louis; Florencia Pascual-Winter, María

    2015-04-01

    Atomic clock transitions are desirable for quantum information storage and processing thanks to the protection from decoherence they provide. In the context of rare- earth-ion-doped crystals for quantum information storage, clock Zeeman or hyperfine transitions have been identified and exploited for long-lived storage in spin degrees of freedom. We present a theoretical and experimental analysis on the existence of an optical clock transition in Tm3+:YAG, in view of storage in optical coherences. The combination of a Zeeman-like term and a quadratic electronic Zeeman term in the Hamiltonian, lead to the existence of a magnetic field amplitude (12 mT) for which the derivative of the optical transition energy with respect to the field amplitude vanishes, regardless of the magnetic field orientation. We have verified this prediction through hole-burning spectroscopy experiments. In addition to that, a study of the behavior of the Hamiltonian as a function of the magnetic field orientation yields the direction for which both derivatives with respect to the magnetic field angular coordinates also vanish. The condition for an optical clock transition with three vanishing partial derivatives is met.

  7. Hanle detection for optical clocks.

    PubMed

    Zhang, Xiaogang; Zhang, Shengnan; Pan, Duo; Chen, Peipei; Xue, Xiaobo; Zhuang, Wei; Chen, Jingbiao

    2015-01-01

    Considering the strong inhomogeneous spatial polarization and intensity distribution of spontaneous decay fluorescence due to the Hanle effect, we propose and demonstrate a universe Hanle detection configuration of electron-shelving method for optical clocks. Experimental results from Ca atomic beam optical frequency standard with electron-shelving method show that a designed Hanle detection geometry with optimized magnetic field direction, detection laser beam propagation and polarization direction, and detector position can improve the fluorescence collection rate by more than one order of magnitude comparing with that of inefficient geometry. With the fixed 423 nm fluorescence, the improved 657 nm optical frequency standard signal intensity is presented. The potential application of the Hanle detection geometry designed for facilitating the fluorescence collection for optical lattice clock with a limited solid angle of the fluorescence collection has been discussed. The Hanle detection geometry is also effective for ion detection in ion optical clock and quantum information experiments. Besides, a cylinder fluorescence collection structure is designed to increase the solid angle of the fluorescence collection in Ca atomic beam optical frequency standard. PMID:25734183

  8. Hanle Detection for Optical Clocks

    PubMed Central

    Zhang, Xiaogang; Zhang, Shengnan; Pan, Duo; Chen, Peipei; Xue, Xiaobo; Zhuang, Wei; Chen, Jingbiao

    2015-01-01

    Considering the strong inhomogeneous spatial polarization and intensity distribution of spontaneous decay fluorescence due to the Hanle effect, we propose and demonstrate a universe Hanle detection configuration of electron-shelving method for optical clocks. Experimental results from Ca atomic beam optical frequency standard with electron-shelving method show that a designed Hanle detection geometry with optimized magnetic field direction, detection laser beam propagation and polarization direction, and detector position can improve the fluorescence collection rate by more than one order of magnitude comparing with that of inefficient geometry. With the fixed 423 nm fluorescence, the improved 657 nm optical frequency standard signal intensity is presented. The potential application of the Hanle detection geometry designed for facilitating the fluorescence collection for optical lattice clock with a limited solid angle of the fluorescence collection has been discussed. The Hanle detection geometry is also effective for ion detection in ion optical clock and quantum information experiments. Besides, a cylinder fluorescence collection structure is designed to increase the solid angle of the fluorescence collection in Ca atomic beam optical frequency standard. PMID:25734183

  9. Clocking in the face of unpredictability beyond quantum uncertainty

    NASA Astrophysics Data System (ADS)

    Madjid, F. Hadi; Myers, John M.

    2015-05-01

    In earlier papers we showed unpredictability beyond quantum uncertainty in atomic clocks, ensuing from a proven gap between given evidence and explanations of that evidence. Here we reconceive a clock, not as an isolated entity, but as enmeshed in a self-adjusting communications network adapted to one or another particular investigation, in contact with an unpredictable environment. From the practical uses of clocks, we abstract a clock enlivened with the computational capacity of a Turing machine, modified to transmit and to receive numerical communications. Such "live clocks" phase the steps of their computations to mesh with the arrival of transmitted numbers. We lift this phasing, known in digital communications, to a principle of logical synchronization, distinct from the synchronization defined by Einstein in special relativity. Logical synchronization elevates digital communication to a topic in physics, including applications to biology. One explores how feedback loops in clocking affect numerical signaling among entities functioning in the face of unpredictable influences, making the influences themselves into subjects of investigation. The formulation of communications networks in terms of live clocks extends information theory by expressing the need to actively maintain communications channels, and potentially, to create or drop them. We show how networks of live clocks are presupposed by the concept of coordinates in a spacetime. A network serves as an organizing principle, even when the concept of the rigid body that anchors a special-relativistic coordinate system is inapplicable, as is the case, for example, in a generic curved spacetime.

  10. Pulsed Optically Pumped Rb clock

    NASA Astrophysics Data System (ADS)

    Micalizio, S.; Levi, F.; Godone, A.; Calosso, C. E.; François, B.; Boudot, R.; Affolderbach, C.; Kang, S.; Gharavipour, M.; Gruet, F.; Mileti, G.

    2016-06-01

    INRIM demonstrated a Rb vapour cell clock based on pulsed optical pumping (POP) with unprecedented frequency stability performances, both in the short and in the medium-long term period. In the frame of a EMRP project, we are developing a new clock based on the same POP principle but adopting solutions aimed at reducing the noise sources affecting the INRIM clock. At the same time, concerning possible technological applications, particular care are devoted in the project to reduce the size and the weight of the clock, still keeping the excellent stability of the INRIM clock. The paper resumes the main results of this activity.

  11. Mercury Ion Clock for a NASA Technology Demonstration Mission.

    PubMed

    Tjoelker, Robert L; Prestage, John D; Burt, Eric A; Chen, Pin; Chong, Yong J; Chung, Sang K; Diener, William; Ely, Todd; Enzer, Daphna G; Mojaradi, Hadi; Okino, Clay; Pauken, Mike; Robison, David; Swenson, Bradford L; Tucker, Blake; Wang, Rabi

    2016-07-01

    There are many different atomic frequency standard technologies but only few meet the demanding performance, reliability, size, mass, and power constraints required for space operation. The Jet Propulsion Laboratory is developing a linear ion-trap-based mercury ion clock, referred to as DSAC (Deep-Space Atomic Clock) under NASA's Technology Demonstration Mission program. This clock is expected to provide a new capability with broad application to space-based navigation and science. A one-year flight demonstration is planned as a hosted payload following an early 2017 launch. This first-generation mercury ion clock for space demonstration has a volume, mass, and power of 17 L, 16 kg, and 47 W, respectively, with further reductions planned for follow-on applications. Clock performance with a signal-to-noise ratio (SNR)*Q limited stability of 1.5E-13/τ(1/2) has been observed and a fractional frequency stability of 2E-15 at one day measured (no drift removed). Such a space-based stability enables autonomous timekeeping of with a technology capable of even higher stability, if desired. To date, the demonstration clock has been successfully subjected to mechanical vibration testing at the 14 grms level, thermal-vacuum operation over a range of 42(°)C, and electromagnetic susceptibility tests. PMID:27019481

  12. Spin squeezing in a Rydberg lattice clock.

    PubMed

    Gil, L I R; Mukherjee, R; Bridge, E M; Jones, M P A; Pohl, T

    2014-03-14

    We theoretically demonstrate a viable approach to spin squeezing in optical lattice clocks via optical dressing of one clock state to a highly excited Rydberg state, generating switchable atomic interactions. For realistic experimental parameters, these interactions are shown to generate over 10 dB of squeezing in large ensembles within a few microseconds and without degrading the subsequent clock interrogation. PMID:24679291

  13. Quasars as very-accurate clock synchronizers

    NASA Technical Reports Server (NTRS)

    Hurd, W. J.; Goldstein, R. M.

    1975-01-01

    Quasars can be employed to synchronize global data communications, geophysical measurements, and atomic clocks. It is potentially two to three orders of magnitude better than presently-used Moon-bounce system. Comparisons between quasar and clock pulses are used to develop correction or synchronization factors for station clocks.

  14. p-Wave Cold Collisions in an Optical Lattice Clock

    SciTech Connect

    Lemke, N. D.; Sherman, J. A.; Oates, C. W.; Ludlow, A. D.; Stecher, J. von; Rey, A. M.

    2011-09-02

    We study ultracold collisions in fermionic ytterbium by precisely measuring the energy shifts they impart on the atoms' internal clock states. Exploiting Fermi statistics, we uncover p-wave collisions, in both weakly and strongly interacting regimes. With the higher density afforded by two-dimensional lattice confinement, we demonstrate that strong interactions can lead to a novel suppression of this collision shift. In addition to reducing the systematic errors of lattice clocks, this work has application to quantum information and quantum simulation with alkaline-earth atoms.

  15. Ultracold lanthanides: from optical clock to a quantum simulator

    NASA Astrophysics Data System (ADS)

    Vishnyakova, G. A.; Golovizin, A. A.; Kalganova, E. S.; Sorokin, V. N.; Sukachev, D. D.; Tregubov, D. O.; Khabarova, K. Yu; Kolachevsky, N. N.

    2016-02-01

    We review the current research on precision spectroscopy and quantum optics applications of laser-cooled lanthanides. We discuss the specific electronic structure of hollow atoms, which determine prospects for application in optical frequency standards and in quantum simulators based on spin interactions in optical lattices. Using the example of the thulium atom, we describe the specifics of laser cooling, optical lattice trapping techniques, and clock transition spectroscopy using spectrally narrow lasers.

  16. JPL Ultrastable Trapped Ion Atomic Frequency Standards.

    PubMed

    Burt, Eric A; Yi, Lin; Tucker, Blake; Hamell, Robert; Tjoelker, Robert L

    2016-07-01

    Recently, room temperature trapped ion atomic clock development at the Jet Propulsion Laboratory (JPL) has focused on three directions: 1) ultrastable atomic clocks, usually for terrestrial applications emphasizing ultimate stability performance and autonomous timekeeping; 2) new atomic clock technology for space flight applications that require strict adherence to size, weight, and power requirements; and 3) miniature clocks. In this paper, we concentrate on the first direction and present a design and the initial results from a new ultrastable clock referred to as L10 that achieves a short-term stability of 4.5 ×10(-14)/τ(1/2) and an initial measurement of no significant drift with an uncertainty of 2.4 ×10(-16) /day over a two-week period. PMID:27249827

  17. Monodisperse atomizers for agricultural aviation applications

    NASA Technical Reports Server (NTRS)

    Christensen, L. S.; Steely, S. L.

    1980-01-01

    Conceptual designs of two monodisperse spray nozzles are described and the rationale used in each design is discussed. The nozzles were designed to eliminate present problems in agricultural aviation applications, such as ineffective plant coverage, drift due to small droplets present in the spray being dispersed, and nonuniform swath coverages. Monodisperse atomization techniques are reviewed and a synopsis of the information obtained concerning agricultural aviation spray applications is presented.

  18. Application of satellite time transfer in autonomous spacecraft clocks. [binary time code

    NASA Technical Reports Server (NTRS)

    Chi, A. R.

    1979-01-01

    The conceptual design of a spacecraft clock that will provide a standard time scale for experimenters in future spacecraft., and can be sychronized to a time scale without the need for additional calibration and validation is described. The time distribution to the users is handled through onboard computers, without human intervention for extended periods. A group parallel binary code, under consideration for onboard use, is discussed. Each group in the code can easily be truncated. The autonomously operated clock not only achieves simpler procedures and shorter lead times for data processing, but also contributes to spacecraft autonomy for onboard navigation and data packetization. The clock can be used to control the sensor in a spacecraft, compare another time signal such as that from the global positioning system, and, if the cost is not a consideration, can be used on the ground in remote sites for timekeeping and control.

  19. End-resonance clock and all-photonic clock

    NASA Astrophysics Data System (ADS)

    Jau, Yuan-Yu; Happer, William; Gong, Fei; Braun, Alan; Kwakernaak, Martin

    2008-02-01

    The end-resonance clock uses strong hyperfine end transition to stabilize the frequency of the local oscillator. Comparing to the conventional 0-0 atomic clock, end resonance has very small spin-exchange broadening effect. The spin-exchange rate is proportional to the number density of the alkali-metal atoms. By using the end resonance, we are able to use very high dense vapor to obtain a much better signal to noise ratio. On the other hand, the end resonance suffers from the first-order magnetic field dependence. This problem, however, can be solved by simultaneously using a Zeeman end resonance to stabilize the magnetic field. Here, we report the most recent result of the end-resonance clock. In addition, we report a whole new technique, push-pull laser-atomic oscillator, which can be thought as all-photonic clock. This new clock requires no local oscillator. It acts like a photonic version of maser, which spontaneously generates modulated laser light and modulated voltage signals. The modulation serves as the clock signal, which is automatically locked to the ground-state hyperfine frequency of alkali-metal atoms.

  20. Rapid prototyping of versatile atom chips for atom interferometry applications.

    NASA Astrophysics Data System (ADS)

    Kasch, Brian; Squires, Matthew; Olson, Spencer; Kroese, Bethany; Imhof, Eric; Kohn, Rudolph; Stuhl, Benjamin; Schramm, Stacy; Stickney, James

    2016-05-01

    We present recent advances in the manipulation of ultracold atoms with ex-vacuo atom chips (i.e. atom chips that are not inside to the UHV chamber). Details will be presented of an experimental system that allows direct bonded copper (DBC) atom chips to be removed and replaced in minutes, requiring minimal re-optimization of parameters. This system has been used to create Bose-Einstein condensates, as well as magnetic waveguides with precisely tunable axial parameters, allowing double wells, pure harmonic confinement, and modified harmonic traps. We investigate the effects of higher order magnetic field contributions to the waveguide, and the implications for confined atom interferometry.

  1. Atomic Data Applications for Supernova Modeling

    NASA Astrophysics Data System (ADS)

    Fontes, Christopher J.

    2013-06-01

    The modeling of supernovae (SNe) incorporates a variety of disciplines, including hydrodynamics, radiation transport, nuclear physics and atomic physics. These efforts require numerical simulation of the final stages of a star's life, the supernova explosion phase, and the radiation that is subsequently emitted by the supernova remnant, which can occur over a time span of tens of thousands of years. While there are several different types of SNe, they all emit radiation in some form. The measurement and interpretation of these spectra provide important information about the structure of the exploding star and the supernova engine. In this talk, the role of atomic data is highlighted as iit pertains to the modeling of supernova spectra. Recent applications [1,2] involve the Los Alamos OPLIB opacity database, which has been used to provide atomic opacities for modeling supernova plasmas under local thermodynamic equilibrium (LTE) conditions. Ongoing work includes the application of atomic data generated by the Los Alamos suite of atomic physics codes under more complicated, non-LTE conditions [3]. As a specific, recent example, a portion of the x-ray spectrum produced by Tycho's supernova remnant (SN 1572) will be discussed [4]. [1] C.L. Fryer et al, Astrophys. J. 707, 193 (2009). [2] C.L. Fryer et al, Astrophys. J. 725, 296 (2009). [3] C.J. Fontes et al, Conference Proceedings for ICPEAC XXVII, J. of Phys: Conf. Series 388, 012022 (2012). [4] K.A. Eriksen et al, Presentation at the 2012 AAS Meeting (Austin, TX). (This work was performed under the auspices of the U.S. Department of Energy by Los Alamos National Laboratory under Contract No. DE-AC52-06NA25396.)

  2. Future Laser-Cooled Microwave Clock Performance

    NASA Technical Reports Server (NTRS)

    Gibble, Kurt

    1997-01-01

    Limitations to the performance of laser-cooled earth and space-based Cs clocks will be critically discussed. The most significant limitation to the stability and accuracy of laser-cooled atomic clocks is the frequency shift due to cold collisions. Because of it, laser-cooled Cs clocks must be operated at low density and this implies that space based Cs clock performance will not be significantly better than earth based. To regain some of the high accuracy and stability lost to the low density, clocks can be designed to multiply launch (or juggle) atoms. Clocks based on other atoms, in particular Rb-87 or possibly Rb-85, may have much smaller cold collision frequency shifts and therefore be capable of higher stability and accuracy, especially in a space environment.

  3. Human Peripheral Clocks: Applications for Studying Circadian Phenotypes in Physiology and Pathophysiology

    PubMed Central

    Saini, Camille; Brown, Steven A.; Dibner, Charna

    2015-01-01

    Most light-sensitive organisms on earth have acquired an internal system of circadian clocks allowing the anticipation of light or darkness. In humans, the circadian system governs nearly all aspects of physiology and behavior. Circadian phenotypes, including chronotype, vary dramatically among individuals and over individual lifespan. Recent studies have revealed that the characteristics of human skin fibroblast clocks correlate with donor chronotype. Given the complexity of circadian phenotype assessment in humans, the opportunity to study oscillator properties by using cultured primary cells has the potential to uncover molecular details difficult to assess directly in humans. Since altered properties of the circadian oscillator have been associated with many diseases including metabolic disorders and cancer, clock characteristics assessed in additional primary cell types using similar technologies might represent an important tool for exploring the connection between chronotype and disease, and for diagnostic purposes. Here, we review implications of this approach for gathering insights into human circadian rhythms and their function in health and disease. PMID:26029154

  4. A Grey Model Based on First Differences in the Application of Satellite Clock Bias Prediction

    NASA Astrophysics Data System (ADS)

    Liang, Yue-ji; Ren, Chao; Yang, Xiu-fa; Pang, Guang-feng; Lan, Lan

    2016-01-01

    In consideration of the characteristics of satellite clock bias (SCB), a grey GM(1,1) model based on the first difference method is proposed. The first differences between the SCB values of two adjacent epoches are firstly derived to obtain the corresponding first difference sequence. Then, a grey model is made based on the sequence to predict the first difference values for the time following. Finally, the predicted first difference sequence is recovered to be the corresponding predicted SCB. The clock bias data provided by the IGS (International GNSS Service) are used as the experimental data, and the cases with different lengths of modeling data and different prediction step lengths are compared and analyzed. The result shows that the prediction accuracy of this method is higher than that of traditional grey GM(1,1) model, especially for the PRN01 satellite clock, whose forecast effect is the best. With the first difference method, the model prediction accuracy and stability can be effectively improved and enhanced. This method is feasible and reliable for the relatively long term SCB prediction.

  5. Rockets, clocks, and gravity

    NASA Astrophysics Data System (ADS)

    Vessot, R. F. C.

    Uses of atomic clocks, telemetry, and spacecraft to test predictions of the General Theory of Relativity are described. The number of cycles of a signal being generated by an atomic clock on board a satellite and directed toward earth stations allows precise determination of movements away or toward the receiving station, with an accuracy of 1/9,192,631,770 when using the outer shell electron to nucleus magnetic interaction of a cesium 133 isotope. Doppler radar serves the same purpose when reflected off the surface of a spacecraft, and radio transmitters landed on Mars have provided a source of signals which are deflected by the sun when orbital positions of earth and Mars are in favorable positions. Goals of the NASA Starprobe mission to measure the gravitational flattening and time/space warping occurring around the sun are outlined.

  6. Physical Time and Thermal Clocks

    NASA Astrophysics Data System (ADS)

    Borghi, Claudio

    2016-07-01

    In this paper I discuss the concept of time in physics. I consider the thermal time hypothesis and I claim that thermal clocks and atomic clocks measure different physical times, whereby thermal time and relativistic time are not compatible with each other. This hypothesis opens the possibility of a new foundation of the theory of physical time, and new perspectives in theoretical and philosophical researches.

  7. Advancing differential atom interferometry for space applications

    NASA Astrophysics Data System (ADS)

    Chiow, Sheng-Wey; Williams, Jason; Yu, Nan

    2016-05-01

    Atom interferometer (AI) based sensors exhibit precision and accuracy unattainable with classical sensors, thanks to the inherent stability of atomic properties. Dual atomic sensors operating in a differential mode further extend AI applicability beyond environmental disturbances. Extraction of the phase difference between dual AIs, however, typically introduces uncertainty and systematic in excess of that warranted by each AI's intrinsic noise characteristics, especially in practical applications and real time measurements. In this presentation, we report our efforts in developing practical schemes for reducing noises and enhancing sensitivities in the differential AI measurement implementations. We will describe an active phase extraction method that eliminates the noise overhead and demonstrates a performance boost of a gravity gradiometer by a factor of 3. We will also describe a new long-baseline approach for differential AI measurements in a laser ranging assisted AI configuration. The approach uses well-developed AIs for local measurements but leverage the mature schemes of space laser interferometry for LISA and GRACE. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a Contract with NASA.

  8. Entangling the lattice clock: Towards Heisenberg-limited timekeeping

    NASA Astrophysics Data System (ADS)

    Weinstein, Jonathan D.; Beloy, Kyle; Derevianko, Andrei

    2010-03-01

    We present a scheme for entangling the atoms of an optical lattice to reduce the quantum projection noise of a clock measurement. The divalent clock atoms are held in a lattice at a ``magic'' wavelength that does not perturb the clock frequency -- to maintain clock accuracy -- while an open-shell J=1/2 ``head'' atom is coherently transported between lattice sites via the lattice polarization. This polarization- dependent ``Archimedes' screw'' transport at magic wavelength takes advantage of the vanishing vector polarizability of the scalar, J=0, clock states of bosonic isotopes of divalent atoms. The on-site interactions between the clock atoms and the head atom are used to engineer entanglement and for clock readout.

  9. Entangling the lattice clock: Towards Heisenberg-limited timekeeping

    NASA Astrophysics Data System (ADS)

    Weinstein, Jonathan D.; Beloy, Kyle; Derevianko, Andrei

    2010-03-01

    A scheme is presented for entangling the atoms of an optical lattice to reduce the quantum projection noise of a clock measurement. The divalent clock atoms are held in a lattice at a “magic” wavelength that does not perturb the clock frequency—to maintain clock accuracy—while an open-shell J=1/2 “head” atom is coherently transported between lattice sites via the lattice polarization. This polarization-dependent “Archimedes’ screw” transport at magic wavelength takes advantage of the vanishing vector polarizability of the scalar, J=0, clock states of bosonic isotopes of divalent atoms. The on-site interactions between the clock atoms and the head atom are used to engineer entanglement and for clock readout.

  10. Entangling the lattice clock: Towards Heisenberg-limited timekeeping

    SciTech Connect

    Weinstein, Jonathan D.; Beloy, Kyle; Derevianko, Andrei

    2010-03-15

    A scheme is presented for entangling the atoms of an optical lattice to reduce the quantum projection noise of a clock measurement. The divalent clock atoms are held in a lattice at a 'magic' wavelength that does not perturb the clock frequency - to maintain clock accuracy - while an open-shell J=1/2 'head' atom is coherently transported between lattice sites via the lattice polarization. This polarization-dependent 'Archimedes' screw' transport at magic wavelength takes advantage of the vanishing vector polarizability of the scalar, J=0, clock states of bosonic isotopes of divalent atoms. The on-site interactions between the clock atoms and the head atom are used to engineer entanglement and for clock readout.

  11. Mercury Atomic Frequency Standards for Space Based Navigation and Timekeeping

    NASA Technical Reports Server (NTRS)

    Tjoelker, R. L.; Burt, E. A.; Chung, S.; Hamell, R. L.; Prestage, J. D.; Tucker, B.; Cash, P.; Lutwak, R.

    2012-01-01

    A low power Mercury Atomic Frequency Standard (MAFS) has been developed and demonstrated on the path towards future space clock applications. A self contained mercury ion breadboard clock: emulating flight clock interfaces, steering a USO local oscillator, and consuming approx 40 Watts has been operating at JPL for more than a year. This complete, modular ion clock instrument demonstrates that key GNSS size, weight, and power (SWaP) requirements can be achieved while still maintaining short and long term performance demonstrated in previous ground ion clocks. The MAFS breadboard serves as a flexible platform for optimizing further space clock development and guides engineering model design trades towards fabrication of an ion clock for space flight.

  12. Application of atomic magnetometry in magnetic particledetection

    SciTech Connect

    Xu, Shoujun; Donaldson, Marcus H.; Pines, Alexander; Rochester,Simon M.; Budker, Dmitry; Yashchuk, Valeriy V.

    2006-09-17

    We demonstrate the detection of magnetic particles carriedby water in a continuous flow using an atomic magnetic gradiometer.Studies on three types of magnetic particles are presented: a singlecobalt particle (diameter ~;150 mum, multi-domain), a suspension ofsuperparamagnetic magnetite particles (diameter ~;1 mum), andferromagnetic cobalt nanoparticles (diameter ~;10 nm, 120 kA/mmagnetization). Estimated detection limits are 20 mum diameter for asingle cobalt particle at a water flow rate 30 ml/min, 5x103 magnetiteparticles at 160 ml/min, and 50 pl for the specific ferromagnetic fluidat 130 ml/min. Possible applications of our method arediscussed.

  13. Heaviside revisited: Distortionless signal transmission through lossy media with application to precision clock synchronization

    NASA Astrophysics Data System (ADS)

    Flake, Robert H.

    2016-02-01

    A recently discovered non-sinusoidal, non-periodic electrical signal in the form of an exponentially rising pulse achieves distortionless propagation at constant velocity through lossy, passive transmission media. This unique property is derived theoretically in the framework of the telegrapher's equation analyzed by Heaviside and confirmed experimentally in propagation of such a pulse along serially connected sections of telephone cable. The utility of the distortion-free pulse within the field of time-domain reflectometry is demonstrated in precise time-of-flight measurement of the reflected signal, with the prospect of enhancing the accuracy of protocols for synchronization of spatially separated clocks.

  14. Femtosecond Er3+ fiber laser for application in an optical clock

    NASA Astrophysics Data System (ADS)

    Gubin, M. A.; Kireev, A. N.; Tausenev, A. V.; Konyashchenko, A. V.; Kryukov, P. G.; Tyurikov, D. A.; Shelkovikov, A. S.

    2007-11-01

    The main elements needed for the realization of a compact femtosecond methane optical clock are developed and studied. A femtosecond laser system on an Er3+ fiber ( λ = 1.55 μm) contains an oscillator, an amplifier, and a fiber with a relatively high nonlinearity in which the supercontinuum radiation is generated in the range 1 2 μm. In the supercontinuum spectrum, the fragments separated by an interval that is close to the methane-optical reference frequency ( λ = 3.39 μm) exhibit an increase in intensity. The supercontinuum radiation is converted into the difference frequency in a nonlinear crystal to the range of the methane-reference frequency ( λ = 3.3 3.5 μm), so that the frequency components of the transformed spectrum have sufficient intensities for the subsequent frequency-phase stabilization with respect to the methane reference. A system that stabilizes the pulse repetition rate of the femtosecond Er3+ laser is also employed. Thus, the repetition rate of the ultrashort pulses of the femtosecond fiber laser is locked to the methane reference. The pulse repetition rate is compared with the standard second. Thus, the scheme of an optical clock is realized.

  15. High-temperature operating 894.6nm-VCSELs with extremely low threshold for Cs-based chip scale atomic clocks.

    PubMed

    Zhang, Jianwei; Zhang, Xing; Zhu, Hongbo; Zhang, Jian; Ning, Yongqiang; Qin, Li; Wang, Lijun

    2015-06-01

    We report on the design and fabrication of 894.6nm vertical-cavity surface-emitting lasers (VCSELs) with extremely low threshold at high temperatures, for use in chip-scale Cs atomic clocks. A new design method based on the analysis of the threshold gain and the desired carrier density for different active region structures was proposed to gain the low transparent current density. The increase of the threshold current at higher temperatures was successfully suppressed by introducing the large gain-cavity detuning of VCSEL. By detuning the gain-cavity mode to be -11nm, the minimum threshold current of only 0.23mA at 70 °C was achieved. The operating temperature for emitting the wavelength of 894.6nm was 110 °C, with the single mode suppression ratio (SMSR) of more than 25dB and the threshold current of only 0.32mA. PMID:26072835

  16. Constructive polarization modulation for coherent population trapping clock

    SciTech Connect

    Yun, Peter Danet, Jean-Marie; Holleville, David; Clercq, Emeric de; Guérandel, Stéphane

    2014-12-08

    We propose a constructive polarization modulation scheme for atomic clocks based on coherent population trapping (CPT). In this scheme, the polarization of a bichromatic laser beam is modulated between two opposite circular polarizations to avoid trapping the atomic populations in the extreme Zeeman sublevels. We show that if an appropriate phase modulation between the two optical components of the bichromatic laser is applied synchronously, the two CPT dark states which are produced successively by the alternate polarizations add constructively. Measured CPT resonance contrasts up to 20% in one-pulse CPT and 12% in two-pulse Ramsey-CPT experiments are reported, demonstrating the potential of this scheme for applications to high performance atomic clocks.

  17. A rubidium clock for SEEK-TALK

    NASA Technical Reports Server (NTRS)

    Riley, W. J.

    1983-01-01

    The development of a tactical rubidium frequency standard (TRFS) for the SEEK-TALK program is discussed. This effort, which is entering the prototype stage, is directed toward the establishment of a production capability for miniature rubidium clocks of medium stability capable of fast warmup and extreme ruggedness for military avionics applications. The overall unit consists of an ultraminiature physics package and four plug-in circuit boards inside a 2 1/2-inch square by 4-inch box. This size is achieved without the extensive use of hybrid microcircuitry, yet is believed to be the smallest atomic frequency standard yet developed.

  18. Self-generating magnetometer with laser pumping employment in “end resonance” wall coated vapor cell atomic clocks

    NASA Astrophysics Data System (ADS)

    Baranov, A. A.; Ermak, S. V.; Smolin, R. V.; Semenov, V. V.

    2016-06-01

    This paper presents the results of two double resonance signals correlation investigation. These signals were observed synchronously in optically oriented Rb87 vapors with laser pumping in a dual scheme: low frequency Mx-magnetometer and microwave frequency discriminator. Analytical studies of the scalar and vector light shift components contribution to the frequency instability of the end resonance microwave transitions are presented. An experimental demonstration of the light shift components mutual compensation in optically pumped Rb87 atoms was provided. The results were processed in terms of Allan variance, which demonstrated an effect of decreasing frequency variation at averaging times more than 100 s for a joint scheme of the end resonance microwave transition and selfgenerating (Mx) magnetometer.

  19. Spin-1/2 Optical Lattice Clock

    SciTech Connect

    Lemke, N. D.; Ludlow, A. D.; Barber, Z. W.; Fortier, T. M.; Diddams, S. A.; Jiang, Y.; Jefferts, S. R.; Heavner, T. P.; Parker, T. E.; Oates, C. W.

    2009-08-07

    We experimentally investigate an optical clock based on {sup 171}Yb (I=1/2) atoms confined in an optical lattice. We have evaluated all known frequency shifts to the clock transition, including a density-dependent collision shift, with a fractional uncertainty of 3.4x10{sup -16}, limited principally by uncertainty in the blackbody radiation Stark shift. We measured the absolute clock transition frequency relative to the NIST-F1 Cs fountain clock and find the frequency to be 518 295 836 590 865.2(0.7) Hz.

  20. Resolving all-order method convergence problems for atomic physics applications

    SciTech Connect

    Gharibnejad, H.; Derevianko, A.; Eliav, E.; Safronova, M. S.

    2011-05-15

    The development of the relativistic all-order method where all single, double, and partial triple excitations of the Dirac-Hartree-Fock wave function are included to all orders of perturbation theory led to many important results for the study of fundamental symmetries, development of atomic clocks, ultracold atom physics, and others, as well as provided recommended values of many atomic properties critically evaluated for their accuracy for a large number of monovalent systems. This approach requires iterative solutions of the linearized coupled-cluster equations leading to convergence issues in some cases where correlation corrections are particularly large or lead to an oscillating pattern. Moreover, these issues also lead to similar problems in the configuration-interaction (CI)+all-order method for many-particle systems. In this work, we have resolved most of the known convergence problems by applying two different convergence stabilizer methods, namely, reduced linear equation and direct inversion of iterative subspace. Examples are presented for B, Al, Zn{sup +}, and Yb{sup +}. Solving these convergence problems greatly expands the number of atomic species that can be treated with the all-order methods and is anticipated to facilitate many interesting future applications.

  1. The NIM Sr Optical Lattice Clock

    NASA Astrophysics Data System (ADS)

    Lin, Y.; Wang, Q.; Li, Y.; Meng, F.; Lin, B.; Zang, E.; Sun, Z.; Fang, F.; Li, T.; Fang, Z.

    2016-06-01

    A 87Sr optical lattice clock is built at the National Institute of Metrology (NIM) of China. The atoms undergo two stages of laser cooling before being loaded into a horizontal optical lattice at the magic wavelength of 813 nm. After being interrogated by a narrow linewidth 698 nm clock laser pulse, the normalized excitation rate is measured to get the frequency error, which is then used to lock the clock laser to the ultra-narrow 1S0-3P0 clock transition. The total systematic uncertainty of the clock is evaluated to be 2.3 × 10-16, and the absolute frequency of the clock is measured to be 429 228 004 229 873.7(1.4) Hz with reference to the NIM5 cesium fountain.

  2. Special Relativistic Clock Comparisons

    NASA Astrophysics Data System (ADS)

    Morton, Tom

    2007-03-01

    Time mappings of a stationary clock's time points onto a moving clock's time line heuristically resolve certain temporal asymmetries in time dilation. Time mapping postulates are identified and transforms are derived. `Clock Re-phasing' vs. `Time Leap' is discussed.

  3. Molecular clocks.

    PubMed

    Lee, Michael S Y; Ho, Simon Y W

    2016-05-23

    In the 1960s, several groups of scientists, including Emile Zuckerkandl and Linus Pauling, had noted that proteins experience amino acid replacements at a surprisingly consistent rate across very different species. This presumed single, uniform rate of genetic evolution was subsequently described using the term 'molecular clock'. Biologists quickly realised that such a universal pacemaker could be used as a yardstick for measuring the timescale of evolutionary divergences: estimating the rate of amino acid exchanges per unit of time and applying it to protein differences across a range of organisms would allow deduction of the divergence times of their respective lineages (Figure 1). PMID:27218841

  4. A Method for Calibrating Molecular Clocks and Its Application to Animal Mitochondrial DNA

    PubMed Central

    Lynch, M.; Jarrell, P. E.

    1993-01-01

    A generalized least-squares procedure is introduced for the calibration of molecular clocks and applied to the complete mitochondrial DNA sequences of 13 animal species. The proposed technique accounts for both nonindependence and heteroscedasticity of molecular-distance data, problems that have not been taken into to account in such analyses in the past. When sequence-identity data are transformed to account for multiple substitutions/site, the molecular divergence scales linearly with time, but with substantially more variation in the substitution rate than expected under a Poisson model. Significant levels of divergence are predicted at zero divergence time for most loci, suggesting high levels of site-specific heterozygosity among mtDNA molecules establishing in sister taxa. For nearly all loci, the baseline heterozygosity is lower and the substitution rate is higher in mammals relative to other animals. There is considerable variation in the evolutionary rate among loci but no compelling evidence that the average rate of mtDNA evolution is elevated with respect to that of nuclear DNA. Using the observed patterns of interspecific divergence, empirical estimates are derived for the mean coalescence times of organelles colonizing sister taxa. PMID:7508408

  5. Double-modulation CPT cesium compact clock

    NASA Astrophysics Data System (ADS)

    Yun, Peter; Mejri, Sinda; Tricot, Francois; Abdel Hafiz, Moustafa; Boudot, Rodolphe; de Clercq, Emeric; Guérandel, Stéphane

    2016-06-01

    Double-modulation coherent population trapping (CPT) is based on a synchronous modulation of Raman phase and laser polarization, which allows the atomic population to accumulate in a common dark state. The high contrast signal obtained on the clock transition with a relative compact and robust laser system is interesting as basis of a high performance microwave clock. Here we study the parameters of a double-modulation CPT Cs clock working in cw mode. The optimal polarization modulation frequency and cell temperature for maximum contrast of clock transition are investigated. The parameters of the detection are also studied. With the optimal parameters, we observe a CPT signal with contrast of 10% and linewidth of 492 Hz, which is well suited for implementing a cw atomic clock.

  6. Timescale algorithms combining cesium clocks and hydrogen masers

    NASA Technical Reports Server (NTRS)

    Breakiron, Lee A.

    1992-01-01

    The United States Naval Observatory (USNO) atomic timescale, formerly based on an ensemble of cesium clocks, is now produced by an ensemble of cesium clocks and hydrogen masers. In order to optimize stability and reliability, equal clock weighting has been replaced by a procedure reflecting the relative, time-varying noise characteristics of the two different types of clocks. Correlation of frequency drift is required, and residual drift is avoided by the eventual complete deweighting of the masers.

  7. Highly precise clocks to test fundamental physics

    NASA Astrophysics Data System (ADS)

    Bize, S.; Wolf, P.

    2012-12-01

    Highly precise atomic clocks and precision oscillators are excellent tools to test founding principles, such as the Equivalence Principle, which are the basis of modern physics. A large variety of tests are possible, including tests of Local Lorentz Invariance, of Local Position Invariance like, for example, tests of the variability of natural constants with time and with gravitation potential, tests of isotropy of space, etc. Over several decades, SYRTE has developed an ensemble of highly accurate atomic clocks and oscillators using a large diversity of atomic species and methods. The SYRTE clock ensemble comprises hydrogen masers, Cs and Rb atomic fountain clocks, Sr and Hg optical lattice clocks, as well as ultra stable oscillators both in the microwave domain (cryogenic sapphire oscillator) and in the optical domain (Fabry-Perot cavity stabilized ultra stable lasers) and means to compare these clocks locally or remotely (fiber links in the RF and the optical domain, femtosecond optical frequency combs, satellite time and frequency transfer methods). In this paper, we list the fundamental physics tests that have been performed over the years with the SYRTE clock ensemble. Several of these tests are done thanks to the collaboration with partner institutes including the University of Western Australia, the Max Planck Institut für Quantenoptik in Germany, and others.

  8. Advances in Atomic Gyroscopes: A View from Inertial Navigation Applications

    PubMed Central

    Fang, JianCheng; Qin, Jie

    2012-01-01

    With the rapid development of modern physics, atomic gyroscopes have been demonstrated in recent years. There are two types of atomic gyroscope. The Atomic Interferometer Gyroscope (AIG), which utilizes the atomic interferometer to sense rotation, is an ultra-high precision gyroscope; and the Atomic Spin Gyroscope (ASG), which utilizes atomic spin to sense rotation, features high precision, compact size and the possibility to make a chip-scale one. Recent developments in the atomic gyroscope field have created new ways to obtain high precision gyroscopes which were previously unavailable with mechanical or optical gyroscopes, but there are still lots of problems that need to be overcome to meet the requirements of inertial navigation systems. This paper reviews the basic principles of AIG and ASG, introduces the recent progress in this area, focusing on discussing their technical difficulties for inertial navigation applications, and suggests methods for developing high performance atomic gyroscopes in the near future. PMID:22778644

  9. Applications of atomic and molecular data to radiation physics

    SciTech Connect

    Inokuti, M.

    1982-01-01

    The general purpose of our work is to provide atomic and molecular collision cross sections useful for radiological physics, dosimetry, and other applications. Studies on the systematics of atomic oscillator-strength spectra and a survey of stopping power data are briefly described. (WHK)

  10. TOPICAL REVIEW: Theory and applications of atomic and ionic polarizabilities

    NASA Astrophysics Data System (ADS)

    Mitroy, J.; Safronova, M. S.; Clark, Charles W.

    2010-10-01

    Atomic polarization phenomena impinge upon a number of areas and processes in physics. The dielectric constant and refractive index of any gas are examples of macroscopic properties that are largely determined by the dipole polarizability. When it comes to microscopic phenomena, the existence of alkaline-earth anions and the recently discovered ability of positrons to bind to many atoms are predominantly due to the polarization interaction. An imperfect knowledge of atomic polarizabilities is presently looming as the largest source of uncertainty in the new generation of optical frequency standards. Accurate polarizabilities for the group I and II atoms and ions of the periodic table have recently become available by a variety of techniques. These include refined many-body perturbation theory and coupled-cluster calculations sometimes combined with precise experimental data for selected transitions, microwave spectroscopy of Rydberg atoms and ions, refractive index measurements in microwave cavities, ab initio calculations of atomic structures using explicitly correlated wavefunctions, interferometry with atom beams and velocity changes of laser cooled atoms induced by an electric field. This review examines existing theoretical methods of determining atomic and ionic polarizabilities, and discusses their relevance to various applications with particular emphasis on cold-atom physics and the metrology of atomic frequency standards.

  11. ENVIRONMENTAL APPLICATION OF GAS CHROMATOGRAPHY/ATOMIC EMISSION DETECTION

    EPA Science Inventory

    A gas chromatography/atomic emission detector (GC/AED) system has been evaluated for its applicability to environmental analysis. Detection limits, elemental response factors, and regression analysis data were determined for 58 semivolatile environmental contaminants. Detection l...

  12. s-Wave collisional frequency shift of a fermion clock.

    PubMed

    Hazlett, Eric L; Zhang, Yi; Stites, Ronald W; Gibble, Kurt; O'Hara, Kenneth M

    2013-04-19

    We report an s-wave collisional frequency shift of an atomic clock based on fermions. In contrast to bosons, the fermion clock shift is insensitive to the population difference of the clock states, set by the first pulse area in Ramsey spectroscopy, θ(1). The fermion shift instead depends strongly on the second pulse area θ(2). It allows the shift to be canceled, nominally at θ(2)=π/2, but correlations perturb the null to slightly larger θ(2). The frequency shift is relevant for optical lattice clocks and increases with the spatial inhomogeneity of the clock excitation field, naturally larger at optical frequencies. PMID:23679589

  13. Synthetic Spin-Orbit Coupling in an Optical Lattice Clock.

    PubMed

    Wall, Michael L; Koller, Andrew P; Li, Shuming; Zhang, Xibo; Cooper, Nigel R; Ye, Jun; Rey, Ana Maria

    2016-01-22

    We propose the use of optical lattice clocks operated with fermionic alkaline-earth atoms to study spin-orbit coupling (SOC) in interacting many-body systems. The SOC emerges naturally during the clock interrogation, when atoms are allowed to tunnel and accumulate a phase set by the ratio of the "magic" lattice wavelength to the clock transition wavelength. We demonstrate how standard protocols such as Rabi and Ramsey spectroscopy that take advantage of the sub-Hertz resolution of state-of-the-art clock lasers can perform momentum-resolved band tomography and determine SOC-induced s-wave collisions in nuclear-spin-polarized fermions. With the use of a second counterpropagating clock beam, we propose a method for engineering controlled atomic transport and study how it is modified by p- and s-wave interactions. The proposed spectroscopic probes provide clean and well-resolved signatures at current clock operating temperatures. PMID:26849600

  14. Synthetic Spin-Orbit Coupling in an Optical Lattice Clock

    NASA Astrophysics Data System (ADS)

    Wall, Michael L.; Koller, Andrew P.; Li, Shuming; Zhang, Xibo; Cooper, Nigel R.; Ye, Jun; Rey, Ana Maria

    2016-01-01

    We propose the use of optical lattice clocks operated with fermionic alkaline-earth atoms to study spin-orbit coupling (SOC) in interacting many-body systems. The SOC emerges naturally during the clock interrogation, when atoms are allowed to tunnel and accumulate a phase set by the ratio of the "magic" lattice wavelength to the clock transition wavelength. We demonstrate how standard protocols such as Rabi and Ramsey spectroscopy that take advantage of the sub-Hertz resolution of state-of-the-art clock lasers can perform momentum-resolved band tomography and determine SOC-induced s -wave collisions in nuclear-spin-polarized fermions. With the use of a second counterpropagating clock beam, we propose a method for engineering controlled atomic transport and study how it is modified by p - and s -wave interactions. The proposed spectroscopic probes provide clean and well-resolved signatures at current clock operating temperatures.

  15. Eliminating Tracking-System Clock Errors

    NASA Technical Reports Server (NTRS)

    Wu, Jiun-Tsong; Bertiger, William I.

    1989-01-01

    Problems of redundancy and correlation avoided. ORTHO computer program eliminates effect of clock errors in differential solutions for positions of users of Global Positioning System (GPS). Main application, elimination of clock errors in tracking system based on GPS. Written in FORTRAN 77.

  16. Noise in state of the art clocks and their impact for fundamental physics

    NASA Technical Reports Server (NTRS)

    Maleki, L.

    2001-01-01

    In this paper a review of the use of advanced atomic clocks in testing the fundamental physical laws will be presented. Noise sources of clocks will be discussed, together with an outline their characterization based on current models. The paper will conclude with a discussion of recent attempts to reduce the fundamental, as well as technical noise in atomic clocks.

  17. Magic wavelengths for terahertz clock transitions

    SciTech Connect

    Zhou Xiaoji; Xu Xia; Chen Xuzong; Chen Jingbiao

    2010-01-15

    Magic wavelengths for laser trapping of boson isotopes of alkaline-earth metal atoms Sr, Ca, and Mg are investigated while considering terahertz clock transitions between the {sup 3}P{sub 0}, {sup 3}P{sub 1}, and {sup 3}P{sub 2} metastable triplet states. Our calculation shows that magic wavelengths for laser trapping do exist. This result is important because those metastable states have already been used to make accurate clocks in the terahertz frequency domain. Detailed discussions for magic wavelengths for terahertz clock transitions are given in this article.

  18. The strontium optical lattice clock: Optical spectroscopy with sub-hertz accuracy

    NASA Astrophysics Data System (ADS)

    Ludlow, Andrew D.

    One of the most well-developed applications of coherent interaction with atoms is atomic frequency standards and clocks. Atomic clocks find significant roles in a number of scientific and technological settings. State-of-the-art, laser-cooled, Cs-fountain microwave clocks have demonstrated impressive frequency measurement accuracy, with fractional uncertainties below the 10-15 level. On the other hand, frequency standards based on optical transitions have made substantial steps forward over the last decade, benefiting from their high operational frequencies. An interesting approach to such an optical standard uses atomic strontium confined in an optical lattice. The tight atomic confinement allows for nearly complete elimination of Doppler and recoil-related effects which can otherwise trouble the precise atomic interrogation. At the same time, the optical lattice is designed to equally perturb the two electronic clock states so that the confinement introduces a net zero shift of the natural transition frequency. This thesis describes the design and realization of an optical frequency standard using 87Sr confined in a 1-D optical lattice. Techniques for atomic manipulation and control are described, including two-stage laser cooling, proper design of atomic confinement in a lattice potential, and optical pumping techniques. With the development of an ultra-stable coherent laser light source, atomic spectral linewidths of the optical clock transition are observed below 2 Hz. High accuracy spectroscopy of the clock transition is carried out utilizing a femtosecond frequency comb referenced to the NIST-F1 Cs fountain. To explore the performance of an improved, spin-polarized Sr standard, a coherent optical phase transfer link is established between JILA and NIST. This enables remote comparison of the Sr standard against optical standards at NIST, such as the cold Ca standard. The high frequency stability of a Sr-Ca comparison (3 x 10-16 at 200 s) is used to make

  19. Possibility of an optical clock using the 6 {sup 1}S{sub 0}{yields}6 {sup 3}P{sub 0}{sup o} transition in {sup 171,173}Yb atoms held in an optical lattice

    SciTech Connect

    Porsev, Sergey G.; Derevianko, Andrei; Fortson, E.N.

    2004-02-01

    We report calculations assessing the ultimate precision of an atomic clock based on the 578 nm 6 {sup 1}S{sub 0}{yields}6 {sup 3}P{sub 0} transition in Yb atoms confined in an optical lattice trap. We find that this transition has a natural linewidth less than 10 mHz in the odd Yb isotopes, caused by hyperfine coupling. The shift in this transition due to the trapping light acting through the lowest order ac polarizability is found to become zero at the magic trap wavelength of about 752 nm. The effects of Rayleigh scattering, multipole polarizabilities, vector polarizability, and hyperfine induced electronic magnetic moments can all be held below 1 mHz (about one part in 10{sup 18}). In the case of the hyperpolarizability, however, larger shifts due to nearly resonant terms cannot be ruled out without an accurate measurement of the magic wavelength.

  20. The JPL near-real-time VLBI system and its application to clock synchronization and earth orientation measurements

    NASA Technical Reports Server (NTRS)

    Callahan, P. S.; Eubanks, T. M.; Roth, M. G.; Steppe, J. A.; Esposito, P. B.

    1983-01-01

    The JPL near-real-time VLBI system called Block I is discussed. The hardware and software of the system are described, and the Time and Earth Motion Precision Observations (TEMPO) which utilize Block I are discussed. These observations are designed to provide interstation clock synchronization to 10 nsec and to determine earth orientation (UT1 and polar motion - UTPM) to 30 cm or better in each component. TEMPO results for clock synchronization and UTPM are presented with data from the July 1980-August 1981 analyzed using the most recent JPL solution software and source catalog. Future plans for TEMPO and Block I are discussed.

  1. Continuous Nondemolition Measurement of the Cs Clock Transition Pseudospin

    SciTech Connect

    Chaudhury, Souma; Smith, Greg A.; Schulz, Kevin; Jessen, Poul S.

    2006-02-03

    We demonstrate a weak continuous measurement of the pseudospin associated with the clock transition in a sample of Cs atoms. Our scheme uses an optical probe tuned near the D{sub 1} transition to measure the sample birefringence, which depends on the z component of the collective pseudospin. At certain probe frequencies the differential light shift of the clock states vanishes, and the measurement is nonperturbing. In dense samples the measurement can be used to squeeze the collective clock pseudospin and has the potential to improve the performance of atomic clocks and interferometers.

  2. Laser Cooling of Lanthanides: from Optical Clocks to Quantum Simulators

    NASA Astrophysics Data System (ADS)

    Golovizin, A.; Kalganova, E.; Vishnyakova, G.; Tregubov, D.; Khabarova, K.; Sorokin, V.; Kolachevsky, N.

    2015-09-01

    We discuss current progress in laser cooling of lanthanides (Er, Yb, Dy, Tm etc.) focusing on applications. We describe some important peculiarities taking Thulium atom as an example: Two stage laser cooling, trapping in an optical lattice, anisotropic interactions and spectroscopy of narrow transitions. Specific level structure and presence of magic wavelengths make ultracold Thulium a favorable candidate for optical clock applications. On the other hand, abundance of Feshbach resonances allow to tune interactions in ultracold gases and thus reach quantum degeneracy. It opens intriguing perspectives for novel quantum simulators employing dipole-dipole interactions in an optical lattice.

  3. The Glyoxal Clock Reaction

    ERIC Educational Resources Information Center

    Ealy, Julie B.; Negron, Alexandra Rodriguez; Stephens, Jessica; Stauffer, Rebecca; Furrow, Stanley D.

    2007-01-01

    Research on the glyoxal clock reaction has led to adaptation of the clock reaction to a general chemistry experiment. This particular reaction is just one of many that used formaldehyde in the past. The kinetics of the glyoxal clock makes the reaction suitable as a general chemistry lab using a Calculator Based Laboratory (CBL) or a LabPro. The…

  4. An Introduction to Atomic Layer Deposition with Thermal Applications

    NASA Technical Reports Server (NTRS)

    Dwivedi, Vivek H.

    2015-01-01

    Atomic Layer Deposition (ALD) is a cost effective nano-manufacturing technique that allows for the conformal coating of substrates with atomic control in a benign temperature and pressure environment. Through the introduction of paired precursor gases thin films can be deposited on a myriad of substrates ranging from glass, polymers, aerogels, and metals to high aspect ratio geometries. This talk will focus on the utilization of ALD for engineering applications.

  5. Atomic properties of Lu+

    NASA Astrophysics Data System (ADS)

    Paez, Eduardo; Arnold, K. J.; Hajiyev, Elnur; Porsev, S. G.; Dzuba, V. A.; Safronova, U. I.; Safronova, M. S.; Barrett, M. D.

    2016-04-01

    Singly ionized lutetium has recently been suggested as a potential clock candidate. Here we report a joint experimental and theoretical investigation of Lu+. Measurements relevant to practical clock operation are made and compared to atomic structure calculations. Calculations of scalar and tensor polarizabilities for clock states over a range of wavelengths are also given. These results will be useful for future work with this clock candidate.

  6. Recent progress of neutral mercury lattice clock in SIOM

    NASA Astrophysics Data System (ADS)

    Zhao, R. C.; Fu, X. H.; Liu, K. K.; Gou, W.; Sun, J. F.; Xu, Z.; Wang, Y. Z.

    2016-06-01

    Neutral mercury atom is one of good candidates of optical lattice clock. Due to its large atomic number, mercury atom is insensitive to black body radiation, which is the severe limitation for the development of optical clocks. However, the challenge of neutral mercury lattice clock is the requirement of high power deep-UV lasers, especially for both the cooling laser and the lattice laser. Here, we report the recent progress of neutral mercury lattice clock in SIOM, including the development for laser cooling of mercury atom and the cooling laser system with fiber laser amplifier. We have realized the magneto-optical trap of mercury atoms and measured the parameters of cold mercury atoms. A home-made external cavity diode laser works as a seed laser for a room temperature 1014.8 nm fiber laser amplifier. A new efficient frequency-doubling cavity from 1015 nm to 507 nm has been developed.

  7. On-chip optical trapping for atomic applications

    NASA Astrophysics Data System (ADS)

    Perez, Maximillian A.; Salim, Evan; Farkas, Daniel; Duggan, Janet; Ivory, Megan; Anderson, Dana

    2014-09-01

    To simplify applications that rely on optical trapping of cold and ultracold atoms, ColdQuanta is developing techniques to incorporate miniature optical components onto in-vacuum atom chips. The result is a hybrid atom chip that combines an in-vacuum micro-optical bench for optical control with an atom chip for magnetic control. Placing optical components on a chip inside of the vacuum system produces a compact system that can be targeted to specific experiments, in this case the generation of optical lattices. Applications that can benefit from this technology include timekeeping, inertial sensing, gravimetry, quantum information, and emulation of quantum many-body systems. ColdQuanta's GlasSi atom chip technology incorporates glass windows in the plane of a silicon atom chip. In conjunction with the in-vacuum micro-optical bench, optical lattices can be generated within a few hundred microns of an atom chip window through which single atomic lattice sites can be imaged with sub-micron spatial resolution. The result is a quantum gas microscope that allows optical lattices to be studied at the level of single lattice sites. Similar to what ColdQuanta has achieved with magneto-optical traps (MOTs) in its miniMOT system and with Bose- Einstein condensates (BECs) in its RuBECi(R) system, ColdQuanta seeks to apply the on-chip optical bench technology to studies of optical lattices in a commercially available, turnkey system. These techniques are currently being considered for lattice experiments in NASA's Cold Atom Laboratory (CAL) slated for flight on the International Space Station.

  8. Clock Laser System for a Strontium Lattice Clock

    NASA Astrophysics Data System (ADS)

    Legero, T.; Lisdat, Ch.; Vellore Winfred, J. S. R.; Schnatz, H.; Grosche, G.; Riehle, F.; Sterr, U.

    2009-04-01

    We describe the setup and the characterization of a 698 nm master-slave diode laser system to probe the 1S0-3P0 clock transition of strontium atoms confined in a 1D optical lattice. The frequency noise and the linewidth of the laser system have been measured with respect to an ultrastable 657 nm diode laser with 1 Hz linewidth. The large frequency difference of more than 25 THz was bridged using a femtosecond fiber comb as transfer oscillator. In a second step the virtual beat was used to establish a phase lock between the narrow line 657 nm laser and the strontium clock laser. This technique allowed to transfer the stability from the 657 nm to the 698 nm laser.

  9. Cold-collision-shift cancellation and inelastic scattering in a Yb optical lattice clock

    SciTech Connect

    Ludlow, A. D.; Lemke, N. D.; Sherman, J. A.; Oates, C. W.; Quemener, G.; Stecher, J. von; Rey, A. M.

    2011-11-15

    Recently, p-wave cold collisions were shown to dominate the density-dependent shift of the clock transition frequency in a {sup 171}Yb optical lattice clock. Here we demonstrate that by operating such a system at the proper excitation fraction, the cold-collision shift is canceled below the 5x10{sup -18} fractional frequency level. We report inelastic two-body loss rates for {sup 3} P{sub 0} -{sup 3} P{sub 0} and {sup 1} S{sub 0} -{sup 3} P{sub 0} scattering. We also measure interaction shifts in an unpolarized atomic sample. Collision measurements for this spin-1/2 {sup 171}Yb system are relevant for high-performance optical clocks as well as strongly interacting systems for quantum information and quantum simulation applications.

  10. Extended Coherence Time on the Clock Transition of Optically Trapped Rubidium

    SciTech Connect

    Kleine Buening, G.; Will, J.; Ertmer, W.; Rasel, E.; Klempt, C.; Arlt, J.; Ramirez-Martinez, F.; Rosenbusch, P.; Piechon, F.

    2011-06-17

    Optically trapped ensembles are of crucial importance for frequency measurements and quantum memories but generally suffer from strong dephasing due to inhomogeneous density and light shifts. We demonstrate a drastic increase of the coherence time to 21 s on the magnetic field insensitive clock transition of {sup 87}Rb by applying the recently discovered spin self-rephasing [C. Deutsch et al., Phys. Rev. Lett. 105, 020401 (2010)]. This result confirms the general nature of this new mechanism and thus shows its applicability in atom clocks and quantum memories. A systematic investigation of all relevant frequency shifts and noise contributions yields a stability of 2.4x10{sup -11{tau}-1/2}, where {tau} is the integration time in seconds. Based on a set of technical improvements, the presented frequency standard is predicted to rival the stability of microwave fountain clocks in a potentially much more compact setup.

  11. A novel method of atomization with potential gas turbine applications

    NASA Astrophysics Data System (ADS)

    Lefebvre, Arthur H.

    1988-10-01

    In conventional airblast or air-assist nozzles the bulk liquid to be atomized is first transformed into a jet or sheet before being exposed to the atomizing air. In the method of atomization described in this paper, the air is introduced into the bulk liquid at some point upstream of the nozzle discharge orifice. This injected air forms bubbles which 'explode' downstream of the injection orifice thereby shattering the liquid into small drops. Experiments carried out on this atomizer, using water as the working fluid and nitrogen as the driving gas, show that good atomization can be achieved using only small amounts of atomizing gas at injection pressures as low as 173 kPa (25 psi). It is found that atomization quality is largely independent of the size of the nozzle discharge orifice. Thus, the system appears to have good potential for applications where small holes and passages cannot be employed due to the risk of blockage by contaminants in the fuel.

  12. Optics and interferometry with atoms and molecules

    SciTech Connect

    Cronin, Alexander D.; Schmiedmayer, Joerg; Pritchard, David E.

    2009-07-15

    Interference with atomic and molecular matter waves is a rich branch of atomic physics and quantum optics. It started with atom diffraction from crystal surfaces and the separated oscillatory fields technique used in atomic clocks. Atom interferometry is now reaching maturity as a powerful art with many applications in modern science. In this review the basic tools for coherent atom optics are described including diffraction by nanostructures and laser light, three-grating interferometers, and double wells on atom chips. Scientific advances in a broad range of fields that have resulted from the application of atom interferometers are reviewed. These are grouped in three categories: (i) fundamental quantum science, (ii) precision metrology, and (iii) atomic and molecular physics. Although some experiments with Bose-Einstein condensates are included, the focus of the review is on linear matter wave optics, i.e., phenomena where each single atom interferes with itself.

  13. A relativistic analysis of clock synchronization

    NASA Technical Reports Server (NTRS)

    Thomas, J. B.

    1974-01-01

    The relativistic conversion between coordinate time and atomic time is reformulated to allow simpler time calculations relating analysis in solar-system barycentric coordinates (using coordinate time) with earth-fixed observations (measuring earth-bound proper time or atomic time.) After an interpretation of terms, this simplified formulation, which has a rate accuracy of about 10 to the minus 15th power, is used to explain the conventions required in the synchronization of a world wide clock network and to analyze two synchronization techniques-portable clocks and radio interferometry. Finally, pertinent experiment tests of relativity are briefly discussed in terms of the reformulated time conversion.

  14. Experimental evaluation of an atomic line filter for spaceborne application

    NASA Astrophysics Data System (ADS)

    Oehry, Bernard P.; Schupita, Walter; Sumetsberger, Brigitte; Molisch, Andreas F.; Magerl, Gottfried

    1994-12-01

    Atomic line filters take advantage of the sharp spectral features offered by electronic transitions in free atoms. The basic idea is to convert a narrow atomic absorption profile into an equally narrow optical transmission filter by detecting the fluorescence radiation that is emitted after a photon has been absorbed. We developed the metastable thallium atomic line filter from the basic physical idea to a laboratory prototype in order to evaluate the usefulness of the technology for satellite borne backscatter LIDARs. Atomic thallium provides for an unsurpassed combination of features for this purpose. The input wavelength of the filter is 535 nm, which matches the frequency doubled Nd:BEL laser. The filter is an active device, it upconverts the 535 nm input into 378 nm output that is detected by a PMT. The experimental results were as expected concerning the characteristics directly related to atomic properties, i.e. the filter has only 10 ns response time, its optical bandwidth is 0.004 nm, and its acceptance angle is only limited by the device geometry. An optimized setup, with the size constraints of a space-borne system, displays a total quantum efficiency of 2%, i.e. from input photons to detected output photons. This constitutes a remarkable and unsurpassed value for atomic line filters but is too low for the application in mind. (A ground-based, scaled-up version of our prototype would reach about 10% quantum efficiency). In addition, the 500 degree(s)C operating temperature of the vapor cell requires sophisticated thermal layout and thermal shielding, which means a lot of added mass and volume. In summary, we found that atomic line filters can be built that offer characteristics not found with other technologies, but their applicability for space borne systems is questionable.

  15. Optimized geometries for future generation optical lattice clocks

    NASA Astrophysics Data System (ADS)

    Krämer, S.; Ostermann, L.; Ritsch, H.

    2016-04-01

    Atoms deeply trapped in magic wavelength optical lattices provide a Doppler- and collision-free dense ensemble of quantum emitters ideal for high-precision spectroscopy and they are the basis of some of the best optical atomic clocks to date. However, despite their minute optical dipole moments the inherent long-range dipole-dipole interactions in such lattices still generate line shifts, dephasing and modified decay. We show that in a perfectly filled lattice line shifts and decay are resonantly enhanced depending on the lattice constant and geometry. Potentially, this yields clock shifts of many atomic linewidths and reduces the measurement by optimizing the lattice geometry. Such collective effects can be tailored to yield zero effective shifts and prolong dipole lifetimes beyond the single-atom decay. In particular, we identify dense 2D hexagonal or square lattices as the most promising configurations for an accuracy and precision well below the independent ensemble limit. This geometry should also be an ideal basis for related applications such as superradiant lasers, precision magnetometry or long-lived quantum memories.

  16. Clock shifts in the Unitary Bose Gas

    NASA Astrophysics Data System (ADS)

    Fletcher, Richard; Man, Jay; Lopes, Raphael; Navon, Nir; Smith, Robert; Hadzibabic, Zoran

    2016-05-01

    Clock shifts are interaction-induced changes in the transition frequency between atomic spin states. So-called because of their importance as systematic errors in atomic clocks, they reveal details of both the interaction energy within a gas and the particle correlations. In this work, we employ a RF-injection technique to rapidly project a thermal Bose gas into the unitary regime on a timescale much shorter than three-body losses. Working with a two-state system, one of which exhibits strong intrastate interactions, we carry out Ramsey spectroscopy to extract the variation in the clock shift across a Feshbach resonance. Thanks to the relationship between these shifts and particle correlations, we use our measurements to infer the contact as a function of both interaction strength and degeneracy. This quantity plays a central role in the many-body physics of strongly correlated systems, offering a link between few-body and thermodynamic behaviour.

  17. Tunable narrow linewidth AlGaInP semiconductor disk laser for Sr atom cooling applications.

    PubMed

    Pabœuf, David; Hastie, Jennifer E

    2016-07-01

    We report a frequency-stabilized semiconductor disk laser based on AlGaInP and operating at 689 nm, a wavelength of interest for atomic clocks based on strontium atoms. With a gain structure designed for emission at around 690 nm, more than 100 mW of output power are generated in single-frequency operation. We show that the source can be tuned over 8 nm with pm precision. By servo-locking the frequency to the side of fringe of a reference cavity, we demonstrate rms frequency noise of 5.2 kHz. PMID:27409180

  18. Nuclear spin effects in optical lattice clocks

    SciTech Connect

    Boyd, Martin M.; Zelevinsky, Tanya; Ludlow, Andrew D.; Blatt, Sebastian; Zanon-Willette, Thomas; Foreman, Seth M.; Ye Jun

    2007-08-15

    We present a detailed experimental and theoretical study of the effect of nuclear spin on the performance of optical lattice clocks. With a state-mixing theory including spin-orbit and hyperfine interactions, we describe the origin of the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition and the differential g factor between the two clock states for alkaline-earth-metal(-like) atoms, using {sup 87}Sr as an example. Clock frequency shifts due to magnetic and optical fields are discussed with an emphasis on those relating to nuclear structure. An experimental determination of the differential g factor in {sup 87}Sr is performed and is in good agreement with theory. The magnitude of the tensor light shift on the clock states is also explored experimentally. State specific measurements with controlled nuclear spin polarization are discussed as a method to reduce the nuclear spin-related systematic effects to below 10{sup -17} in lattice clocks.

  19. Lattice-induced nonadiabatic frequency shifts in optical lattice clocks

    SciTech Connect

    Beloy, K.

    2010-09-15

    We consider the frequency shift in optical lattice clocks which arises from the coupling of the electronic motion to the atomic motion within the lattice. For the simplest of three-dimensional lattice geometries this coupling is shown to affect only clocks based on blue-detuned lattices. We have estimated the size of this shift for the prospective strontium lattice clock operating at the 390-nm blue-detuned magic wavelength. The resulting fractional frequency shift is found to be on the order of 10{sup -18} and is largely overshadowed by the electric quadrupole shift. For lattice clocks based on more complex geometries or other atomic systems, this shift could potentially be a limiting factor in clock accuracy.

  20. The absolute frequency of the 87Sr optical clock transition

    NASA Astrophysics Data System (ADS)

    Campbell, Gretchen K.; Ludlow, Andrew D.; Blatt, Sebastian; Thomsen, Jan W.; Martin, Michael J.; de Miranda, Marcio H. G.; Zelevinsky, Tanya; Boyd, Martin M.; Ye, Jun; Diddams, Scott A.; Heavner, Thomas P.; Parker, Thomas E.; Jefferts, Steven R.

    2008-10-01

    The absolute frequency of the 1S0-3P0 clock transition of 87Sr has been measured to be 429 228 004 229 873.65 (37) Hz using lattice-confined atoms, where the fractional uncertainty of 8.6 × 10-16 represents one of the most accurate measurements of an atomic transition frequency to date. After a detailed study of systematic effects, which reduced the total systematic uncertainty of the Sr lattice clock to 1.5 × 10-16, the clock frequency is measured against a hydrogen maser which is simultaneously calibrated to the US primary frequency standard, the NIST Cs fountain clock, NIST-F1. The comparison is made possible using a femtosecond laser based optical frequency comb to phase coherently connect the optical and microwave spectral regions and by a 3.5 km fibre transfer scheme to compare the remotely located clock signals.

  1. Egyptian "Star Clocks"

    NASA Astrophysics Data System (ADS)

    Symons, Sarah

    Diagonal, transit, and Ramesside star clocks are tables of astronomical information occasionally found in ancient Egyptian temples, tombs, and papyri. The tables represent the motions of selected stars (decans and hour stars) throughout the Egyptian civil year. Analysis of star clocks leads to greater understanding of ancient Egyptian constellations, ritual astronomical activities, observational practices, and pharaonic chronology.

  2. Biological Clocks & Circadian Rhythms

    ERIC Educational Resources Information Center

    Robertson, Laura; Jones, M. Gail

    2009-01-01

    The study of biological clocks and circadian rhythms is an excellent way to address the inquiry strand in the National Science Education Standards (NSES) (NRC 1996). Students can study these everyday phenomena by designing experiments, gathering and analyzing data, and generating new experiments. As students explore biological clocks and circadian…

  3. BUGS system clock distributor

    NASA Astrophysics Data System (ADS)

    Dietrich, Thomas M.

    1991-11-01

    A printed circuit board which will provide external clocks and precisely measure the time at which events take place was designed for the Bristol University Gas Spectrometer (BUGS). The board, which was designed to interface both mechanically and electrically to the Computer Automated Measurement and Control (CAMAC) system, has been named the BUGS system clock control. The board's design and use are described.

  4. Key technologies and applications of laser cooling and trapping 87Rb atomic system

    NASA Astrophysics Data System (ADS)

    Ru, Ning; Zhang, Li; Wang, Yu; Fan, Shangchun

    2016-06-01

    Atom Interferometry is proved to be a potential method for measuring the acceleration of atoms due to Gravity, we are now building a feasible system of cold atom gravimeter. In this paper development and the important applications of laser cooling and trapping atoms are introduced, some key techniques which are used to obtain 87Rb cold atoms in our experiments are also discussed.

  5. Using optical clock to probe quantum many-body physics

    NASA Astrophysics Data System (ADS)

    Ye, Jun

    2016-05-01

    The progress of optical lattice clock has benefited greatly from the understanding of atomic interactions. At the same time, the precision of clock spectroscopy has been applied to explore many-body spin interactions including SU(N) symmetry. Our recent work on this combined front of quantum metrology and many-body physics includes the probe of spin-orbital physics in the lattice clock and the investigation of a Fermi degenerate gas of 105 87Sr atoms in a three-dimensional magic-wavelength optical lattice.

  6. The clock-aided RAIM method and it's application in improving the positioning precision of GPS receiver

    NASA Astrophysics Data System (ADS)

    Shi, Yibing; Teng, Yunlong

    2012-08-01

    The prediction precision of receiver clock bias (RCB) is an important factor in influencing the receiver autonomous integrity monitoring (RAIM) method augmented with it and improving GPS receiver positioning precision. According to the characters of the RCB series, a new prediction model in discrete grey form is presented in this paper, and then the initial value of the model is determined by establishing unconstrained optimised formula. The prediction model is utilised to augment RAIM method in order to identify faulty satellite and improve the positioning precision of GPS receiver. Experimental results show that the prediction model is fit for predicting the RCB series, and the RAIM method aided by it is feasible. The auxiliary RAIM method can not only enhance the efficiency of identifying faulty satellite, but also improve the positioning precision of GPS receiver obviously.

  7. Frequency Metrology with Optical Lattice Clocks

    NASA Astrophysics Data System (ADS)

    Hong, Feng-Lei; Katori, Hidetoshi

    2010-08-01

    The precision measurement of time and frequency is of great interest for a wide range of applications, including fundamental science and technologies that support broadband communication networks and the navigation with global positioning systems (GPSs). The development of optical frequency measurement based on frequency combs has revolutionized the field of frequency metrology, especially research on optical frequency standards. The proposal and realization of the optical lattice clock have further stimulated studies in the field of optical frequency metrology. Optical carrier transfer using optical fibers has been used to disseminate optical frequencies or compare two optical clocks without degrading their stability and accuracy. In this paper, we review the state-of-the-art development of optical frequency combs, standards, and transfer techniques with emphasis on optical lattice clocks. We address recent results achieved at the University of Tokyo and the National Metrology Institute of Japan in respect of frequency metrology with Sr and Yb optical lattice clocks.

  8. Flies, clocks and evolution.

    PubMed Central

    Rosato, E; Kyriacou, C P

    2001-01-01

    The negative feedback model for gene regulation of the circadian mechanism is described for the fruitfly, Drosophila melanogaster. The conservation of function of clock molecules is illustrated by comparison with the mammalian circadian system, and the apparent swapping of roles between various canonical clock gene components is highlighted. The role of clock gene duplications and divergence of function is introduced via the timeless gene. The impressive similarities in clock gene regulation between flies and mammals could suggest that variation between more closely related species within insects might be minimal. However, this is not borne out because the expression of clock molecules in the brain of the giant silk moth, Antheraea pernyi, is not easy to reconcile with the negative feedback roles of the period and timeless genes. Variation in clock gene sequences between and within fly species is examined and the role of co-evolution between and within clock molecules is described, particularly with reference to adaptive functions of the circadian phenotype. PMID:11710984

  9. Circadian Clocks and Metabolism

    PubMed Central

    Marcheva, Biliana; Ramsey, Kathryn M.; Peek, Clara B.; Affinati, Alison; Maury, Eleonore; Bass, Joseph

    2014-01-01

    Circadian clocks maintain periodicity in internal cycles of behavior, physiology, and metabolism, enabling organisms to anticipate the 24-h rotation of the Earth. In mammals, circadian integration of metabolic systems optimizes energy harvesting and utilization across the light/dark cycle. Disruption of clock genes has recently been linked to sleep disorders and to the development of cardiometabolic disease. Conversely, aberrant nutrient signaling affects circadian rhythms of behavior. This chapter reviews the emerging relationship between the molecular clock and metabolic systems and examines evidence that circadian disruption exerts deleterious consequences on human health. PMID:23604478

  10. [Application of atomic absorption spectrometry in the engine knock detection].

    PubMed

    Chen, Li-Dan

    2013-02-01

    Because existing human experience diagnosis method and apparatus for auxiliary diagnosis method are difficult to diagnose quickly engine knock. Atomic absorption spectrometry was used to detect the automobile engine knock in in innovative way. After having determined Fe, Al, Cu, Cr and Pb content in the 35 groups of Audi A6 engine oil whose travel course is 2 000 -70 000 kilometers and whose sampling interval is 2 000 kilometers by atomic absorption spectrometry, the database of primary metal content in the same automobile engine at different mileage was established. The research shows that the main metal content fluctuates within a certain range. In practical engineering applications, after the determination of engine oil main metal content and comparison with its database value, it can not only help to diagnose the type and location of engine knock without the disintegration and reduce vehicle maintenance costs and improve the accuracy of engine knock fault diagnosis. PMID:23697150

  11. Conditional ramsey spectroscopy with synchronized atoms.

    PubMed

    Xu, Minghui; Holland, M J

    2015-03-13

    We investigate Ramsey spectroscopy performed on a synchronized ensemble of two-level atoms. The synchronization is induced by the collective coupling of the atoms to a heavily damped mode of an optical cavity. We show that, in principle, with this synchronized system it is possible to observe Ramsey fringes indefinitely, even in the presence of spontaneous emission and other sources of individual-atom dephasing. This could have important consequences for atomic clocks and a wide range of precision metrology applications. PMID:25815931

  12. Lutetium +: A better clock candidate

    NASA Astrophysics Data System (ADS)

    Arnold, Kyle; Paez, Eduardo; Haciyev, Elnur; Arifin, Arifin; Cazan, Radu; Barrett, Murray

    2015-05-01

    With the extreme precision now reached by optical clocks it is reasonable to consider redefinition of the frequency standard. In doing so it is important to look beyond the current best-case efforts and have an eye on future possibilities. We will argue that singly ionized Lutetium is a strong candidate for the next generation of optical frequency standards. Lu + has a particularly narrow optical transition in combination with several advantageous properties for managing systematic uncertainties compared to the other atomic species. We summarize these properties and our specific strategies for managing the uncertainties due to external perturbations. Finally, we present the status of our ongoing experiments with trapped Lu +, including the results of precision measurements of its atomic structure.

  13. Short-term GNSS satellite clock stability

    NASA Astrophysics Data System (ADS)

    Griggs, E.; Kursinski, E. R.; Akos, D.

    2015-08-01

    Global Navigation Satellite System (GNSS) clock stability is characterized via the modified Allan deviation using active hydrogen masers as the receiver frequency reference. The high stability of the maser reference allows the GNSS clock contribution to the GNSS carrier phase variance to be determined quite accurately. Satellite clock stability for four different GNSS constellations are presented, highlighting the similarities and differences between the constellations as well as satellite blocks and clock types. Impact on high-rate applications, such as GNSS radio occultation (RO), is assessed through the calculation of the maximum carrier phase error due to clock instability. White phase noise appears to dominate at subsecond time scales. However, while we derived the theoretical contribution of white phase modulation to the modified Allan deviation, our analysis of the GNSS satellite clocks was limited to 1-200 s time scales because of inconsistencies between the subsecond results from the commercial and software-defined receivers. The rubidium frequency standards on board the Global Positioning System (GPS) Block IIF, BeiDou, and Galileo satellites show improved stability results in comparison to previous GPS blocks for time scales relevant to RO. The Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) satellites are the least stable of the GNSS constellations in the short term and will need high-rate corrections to produce RO results comparable to those from the other GNSS constellations.

  14. Iodine Clock Reaction.

    ERIC Educational Resources Information Center

    Mitchell, Richard S.

    1996-01-01

    Describes a combination of solutions that can be used in the study of kinetics using the iodine clock reaction. The combination slows down degradation of the prepared solutions and can be used successfully for several weeks. (JRH)

  15. Resetting Biological Clocks

    ERIC Educational Resources Information Center

    Winfree, Arthur T.

    1975-01-01

    Reports on experiments conducted on two biological clocks, in organisms in the plant and animal kingdoms, which indicate that biological oscillation can be arrested by a single stimulus of a definite strength delivered at the proper time. (GS)

  16. A Two-Photon E1-M1 Optical Clock

    NASA Astrophysics Data System (ADS)

    Alden, Emily A.

    Innovations in precision frequency measurement advance popular technologies such as global positioning systems (GPS), permit the testing of fundamental physics constants, and have the potential to measure local variations in gravity. Driving optical transitions for frequency measurement using an E1-M1 excitation scheme in a hot mercury (Hg) vapor cell is viable and could be the basis of a portable optical frequency standard with comparable accuracy to the most precise atomic clocks in the world. This dissertation explores the fundamental physics of the new E1-M1 method of high-precision frequency measurement in an optical, atomic clock and describes the construction of a high-power E1-M1 clock laser. The value of this new scheme compared to existing optical frequency standards is the simplicity and portability of the experimental setup. Such an optical frequency standard would permit frequency measurement in far-flung locations on earth and in space. Analysis of both the E1-M1 optical transition and thermal properties of the candidate clock atoms are presented. These models allow a stability estimate of an E1-M1 optical clock and recommend experimental settings to optimize the standard. The experimental work that has been performed in pursuit of observing the E1-M1 clock transition in Hg is also discussed. An optical clock operates by making a precision frequency measurement of a laser that has been brought into resonance with a clock atom's oscillator: a high quality atomic level transition. Group II type atoms, such as Hg, have the 1S0-3P0 transition that is an ideal basis for a clock. The E1-M1 excitation is performed by driving the two-photon allowed transition 1S0-3P1-3P0. This is in contrast to the single-photon E1 transition used in other systems. Single-photon schemes must use ultracold atoms to reduce atomic motion to attain high levels of accuracy. Driving the clock transition with a pair of degenerate counter-propagating photons in an E1-M1 scheme

  17. Test of the gravitational redshift with stable clocks in eccentric orbits: application to Galileo satellites 5 and 6

    NASA Astrophysics Data System (ADS)

    Delva, P.; Hees, A.; Bertone, S.; Richard, E.; Wolf, P.

    2015-12-01

    The Einstein Equivalence Principle (EEP) is one of the foundations of the theory of General Relativity and several alternative theories of gravitation predict violations of the EEP. Experimental constraints on this fundamental principle of nature are therefore of paramount importance. The EEP can be split into three sub-principles: the universality of free fall (UFF), the local Lorentz invariance (LLI) and the local position invariance (LPI). In this paper we propose to use stable clocks in eccentric orbits to perform a test of the gravitational redshift, a consequence of the LPI. The best test to date was performed with the Gravity Probe A (GP-A) experiment in 1976 with an uncertainty of 1.4× {10}-4. Our proposal considers the opportunity of using Galileo satellites 5 and 6 to improve on the GP-A test uncertainty. We show that considering realistic noise and systematic effects, and thanks to a highly eccentric orbit, it is possible to improve on the GP-A limit to an uncertainty around (3-4)× {10}-5 after one year of integration of Galileo 5 and 6 data.

  18. A Compact, High Performance Atomic Magnetometer for Biomedical Applications

    PubMed Central

    Shah, Vishal K.; Wakai, Ronald T.

    2013-01-01

    We present a highly sensitive room-temperature atomic magnetometer (AM), designed for use in biomedical applications. The magnetometer sensor head is only 2×2×5 cm3 and is constructed using readily available, low-cost optical components. The magnetic field resolution of the AM is <10 fT/√Hz, which is comparable to cryogenically cooled superconducting quantum interference device (SQUID) magnetometers. We present side-by-side comparisons between our AM and a SQUID magnetometer, and show that equally high quality magnetoencephalography (MEG) and magnetocardiography (MCG) recordings can be obtained using our AM. PMID:24200837

  19. Storage, transportation, and atomization of CWF for residential applications

    SciTech Connect

    Grimanis, M.P.; Breault, R.W. ); Smit, F.J.; Jha, M.C. )

    1991-11-01

    This project investigated the properties and behavior with regard to handling, storage, and atomization in small-scale applications of different CWFs (coal water fuels) prepared from different parent coals and various beneficiation techniques as well as consideration for bulk storage and distribution. The CWFs that were prepared included Upper Elkhorn No. 3, Illinois No. 6, and Upper Wyodak coal cleaned by heavy media separation. Also, several CWFs were prepared with Upper Elkhorn No. 3 coal cleaned by heavy media separation with filtration, chemical cleaning, oil agglomeration, and froth flotation.

  20. Application of compressed sensing to the simulation of atomic systems

    PubMed Central

    Andrade, Xavier; Sanders, Jacob N.; Aspuru-Guzik, Alán

    2012-01-01

    Compressed sensing is a method that allows a significant reduction in the number of samples required for accurate measurements in many applications in experimental sciences and engineering. In this work, we show that compressed sensing can also be used to speed up numerical simulations. We apply compressed sensing to extract information from the real-time simulation of atomic and molecular systems, including electronic and nuclear dynamics. We find that, compared to the standard discrete Fourier transform approach, for the calculation of vibrational and optical spectra the total propagation time, and hence the computational cost, can be reduced by approximately a factor of five. PMID:22891294

  1. Atomic Force Microscopy Application in Biological Research: A Review Study

    PubMed Central

    Vahabi, Surena; Nazemi Salman, Bahareh; Javanmard, Anahita

    2013-01-01

    Atomic force microscopy (AFM) is a three-dimensional topographic technique with a high atomic resolution to measure surface roughness. AFM is a kind of scanning probe microscope, and its near-field technique is based on the interaction between a sharp tip and the atoms of the sample surface. There are several methods and many ways to modify the tip of the AFM to investigate surface properties, including measuring friction, adhesion forces and viscoelastic properties as well as determining the Young modulus and imaging magnetic or electrostatic properties. The AFM technique can analyze any kind of samples such as polymers, adsorbed molecules, films or fibers, and powders in the air whether in a controlled atmosphere or in a liquid medium. In the past decade, the AFM has emerged as a powerful tool to obtain the nanostructural details and biomechanical properties of biological samples, including biomolecules and cells. The AFM applications, techniques, and -in particular- its ability to measure forces, are not still familiar to most clinicians. This paper reviews the literature on the main principles of the AFM modality and highlights the advantages of this technique in biology, medicine, and- especially- dentistry. This literature review was performed through E-resources, including Science Direct, PubMed, Blackwell Synergy, Embase, Elsevier, and Scholar Google for the references published between 1985 and 2010. PMID:23825885

  2. Evolution of the International Atomic Time TAI computation

    NASA Technical Reports Server (NTRS)

    Granveaud, M.

    1979-01-01

    The computation of the International Atomic Time (TAI), a worldwide time reference, is briefly examined. The types of atomic clocks, computation procedures, and time intercomparison between clocks utilizing navigation satellites are addressed. Changes in the system would essentially depend on the improvement of the atomic clocks.

  3. A self-interfering clock as a "which path" witness.

    PubMed

    Margalit, Yair; Zhou, Zhifan; Machluf, Shimon; Rohrlich, Daniel; Japha, Yonathan; Folman, Ron

    2015-09-11

    In Einstein's general theory of relativity, time depends locally on gravity; in standard quantum theory, time is global-all clocks "tick" uniformly. We demonstrate a new tool for investigating time in the overlap of these two theories: a self-interfering clock, comprising two atomic spin states. We prepare the clock in a spatial superposition of quantum wave packets, which evolve coherently along two paths into a stable interference pattern. If we make the clock wave packets "tick" at different rates, to simulate a gravitational time lag, the clock time along each path yields "which path" information, degrading the pattern's visibility. In contrast, in standard interferometry, time cannot yield "which path" information. This proof-of-principle experiment may have implications for the study of time and general relativity and their impact on fundamental effects such as decoherence and the emergence of a classical world. PMID:26249229

  4. Technology development for laser-cooled clocks on the International Space Station

    NASA Technical Reports Server (NTRS)

    Klipstein, W. M.

    2003-01-01

    The PARCS experiment will use a laser-cooled cesium atomic clock operating in the microgravity environment aboard the International Space Station to provide both advanced tests of gravitational theory to demonstrate a new cold-atom clock technology for space.

  5. Atomic frequency standards at NICT

    NASA Astrophysics Data System (ADS)

    Ido, T.; Fujieda, M.; Hachisu, H.; Hayasaka, K.; Kajita, M.; Kojima, R.; Kumagai, M.; Locke, C.; Li, Y.; Matsubara, K.; Nogami, A.; Shiga, N.; Yamaguchi, A.; Koyama, Y.; Hosokawa, M.; Hanado, Y.

    2011-10-01

    Various activities of atomic frequency standards studied in National Institute of Information and Communications Technology (NICT) are briefly reviewed. After BIPM accepted the first cesium fountain clock in NICT as a reference to determine International Atomic Time (TAI), efforts to further reduce the uncertainty of collision shifts are ongoing. A second fountain clock using atomic molasses is being built to enable the operation with less atomic density. Single ion clock using calcium has been pursued for several years in NICT. The absolute frequency measured in 2008 has CIPM to adopt the Ca+ clock transition as a part of the list of radiation (LoR) to realize the meter. Sr lattice clock has started its operation last year. The absolute frequency agreed well with those obtained in other institutes. Study of stable cavities to stabilize clock lasers are also introduced.

  6. Spectroscopy of the 199Hg Optical Clock Transition at 265.5 nm

    NASA Astrophysics Data System (ADS)

    Lytle, Christian; Paul, Justin; Jones, R.

    2013-05-01

    Neutral Hg is an excellent candidate for a stable and accurate atomic clock. The doubly-forbidden clock transition at 265.5 nm can provide an extremely high-quality resonance factor (Q) when confined in an optical lattice at the Stark-shift free ``magic'' wavelength. A key feature of the Hg system is the expected reduced uncertainty of black-body radiation induced Stark shifts compared to other optically-based neutral atom clocks. We demonstrate precision spectroscopy of the 1S0 - 3P0 clock transition in 199Hg in a MOT. The MOT population of 106 atoms was depleted by over 70% using 3 mW from a cavity-stabilized probe laser tuned to the clock transition. We present our characterization of the transition and efforts to implement a stable Hg clock system.

  7. Towards a portable optical clock based on a two-photon transition

    NASA Astrophysics Data System (ADS)

    Potnis, Shreyas; Jackson, Shira; Vutha, Amar

    2016-05-01

    Optical clocks based on narrow linewidth atomic transitions have achieved an unprecedented level of precision. These clocks rely on tight confinement of atoms by light, to mitigate Doppler shifts and atomic recoil, with the trapping light appropriately tuned to a ``magic'' wavelength to eliminate light shifts. An alternative approach is construct optical clocks using inherently Doppler-free two-photon transitions, which can lead to a substantially simplified architecture. The short cycle time and large atom numbers available with such a scheme enable rapid, high signal-to-noise measurements, paving the way for portable and autonomous clocks. We report on experimental progress towards constructing an optical clock based on the 4s21S0 --> 4 s 3 d1D2 two-photon transition in laser cooled 40Ca atoms.

  8. Clock synchronisation experiment in India using symphonie satellite

    NASA Technical Reports Server (NTRS)

    Somayajulu, Y. V.; Mathur, B. S.; Banerjee, P.; Garg, S. C.; Singh, L.; Sood, P. C.; Tyagi, T. R.; Jain, C. L.; Kumar, K.

    1979-01-01

    A recent clock synchronization experiment between the National Physical Laboratory (NPL), New Delhi and Space Applications Center (SAC), Ahemedabad, in India via geostationary satellite symphonie 2, stationed at 49 E longitude, is reported. A two-way transmission using a microwave transponder considered to provide the greatest precision in synchronization of two remote clocks is described.

  9. Nuclear magnetic resonance implementation of a quantum clock synchronization algorithm

    SciTech Connect

    Zhang Jingfu; Long, G.C; Liu Wenzhang; Deng Zhiwei; Lu Zhiheng

    2004-12-01

    The quantum clock synchronization (QCS) algorithm proposed by Chuang [Phys. Rev. Lett. 85, 2006 (2000)] has been implemented in a three qubit nuclear magnetic resonance quantum system. The time difference between two separated clocks can be determined by measuring the output states. The experimental realization of the QCS algorithm also demonstrates an application of the quantum phase estimation.

  10. Plowshare Program - American Atomic Bomb Tests For Industrial Applications

    ScienceCinema

    None

    2014-07-31

    The United States Atomic Energy Commission (AEC) established the Plowshare Program as a research and development activity to explore the technical and economic feasibility of using nuclear explosives for industrial applications. The reasoning was that the relatively inexpensive energy available from nuclear explosions could prove useful for a wide variety of peaceful purposes. The Plowshare Program began in 1958 and continued through 1975. Between December 1961 and May 1973, the United States conducted 27 Plowshare nuclear explosive tests comprising 35 individual detonations. Conceptually, industrial applications resulting from the use of nuclear explosives could be divided into two broad categories: 1) large-scale excavation and quarrying, where the energy from the explosion was used to break up and/or move rock; and 2) underground engineering, where the energy released from deeply buried nuclear explosives increased the permeability and porosity of the rock by massive breaking and fracturing. Possible excavation applications included: canals, harbors, highway and railroad cuts through mountains, open pit mining, construction of dams, and other quarry and construction-related projects. Underground nuclear explosion applications included: stimulation of natural gas production, preparation of leachable ore bodies for in situ leaching, creation of underground zones of fractured oil shale for in situ retorting, and formation of underground natural gas and petroleum storage reservoirs.

  11. Plowshare Program - American Atomic Bomb Tests For Industrial Applications

    SciTech Connect

    2012-04-22

    The United States Atomic Energy Commission (AEC) established the Plowshare Program as a research and development activity to explore the technical and economic feasibility of using nuclear explosives for industrial applications. The reasoning was that the relatively inexpensive energy available from nuclear explosions could prove useful for a wide variety of peaceful purposes. The Plowshare Program began in 1958 and continued through 1975. Between December 1961 and May 1973, the United States conducted 27 Plowshare nuclear explosive tests comprising 35 individual detonations. Conceptually, industrial applications resulting from the use of nuclear explosives could be divided into two broad categories: 1) large-scale excavation and quarrying, where the energy from the explosion was used to break up and/or move rock; and 2) underground engineering, where the energy released from deeply buried nuclear explosives increased the permeability and porosity of the rock by massive breaking and fracturing. Possible excavation applications included: canals, harbors, highway and railroad cuts through mountains, open pit mining, construction of dams, and other quarry and construction-related projects. Underground nuclear explosion applications included: stimulation of natural gas production, preparation of leachable ore bodies for in situ leaching, creation of underground zones of fractured oil shale for in situ retorting, and formation of underground natural gas and petroleum storage reservoirs.

  12. Cold Atom Source Containing Multiple Magneto-Optical Traps

    NASA Technical Reports Server (NTRS)

    Ramirez-Serrano, Jaime; Kohel, James; Kellogg, James; Lim, Lawrence; Yu, Nan; Maleki, Lute

    2007-01-01

    An apparatus that serves as a source of a cold beam of atoms contains multiple two-dimensional (2D) magneto-optical traps (MOTs). (Cold beams of atoms are used in atomic clocks and in diverse scientific experiments and applications.) The multiple-2D-MOT design of this cold atom source stands in contrast to single-2D-MOT designs of prior cold atom sources of the same type. The advantages afforded by the present design are that this apparatus is smaller than prior designs.

  13. Ultracold photodissociation and progress towards a molecular lattice clock with 88 Sr

    NASA Astrophysics Data System (ADS)

    Lee, Chih-Hsi; McGuyer, Bart; McDonald, Mickey; Apfelback, Florian; Grier, Andrew; Zelevinsky, Tanya

    2016-05-01

    Techniques originally developed for the construction of atomic clocks can be adapted to the study of ultracold molecules, with applications ranging from studies of ultracold chemistry to searches for new physics. We present recent experimental results involving studies of fully quantum state-resolved photodissociation of 88 Sr2 molecules, as well as progress toward building a molecular clock. First, our system has allowed for precise, quantum state-resolved photodissociation studies, revealing not only excellent control over quantum states but also a more accurate way to describe the photodissociation of diatomic molecules and access ultracold chemistry. Second, the molecular clock will allow us to search for a possible time variation of the proton-electron mass ratio. The ``oscillator'' of such a molecular clock would consist of the frequency difference between two lasers driving a two-photon Raman transition between deeply and intermediately-bound rovibrational levels in the electronic ground state. Accomplishing this task requires exploring several research directions, including the precision spectroscopy of bound states and developing tools for the control and minimization of differential lattice light shifts.

  14. A single-atom detector integrated on an atom chip: fabrication, characterization and application

    NASA Astrophysics Data System (ADS)

    Heine, D.; Rohringer, W.; Fischer, D.; Wilzbach, M.; Raub, T.; Loziczky, S.; Liu, XiYuan; Groth, S.; Hessmo, B.; Schmiedmayer, J.

    2010-09-01

    We describe a robust and reliable fluorescence detector for single atoms that is fully integrated on an atom chip. The detector allows spectrally and spatially selective detection of atoms, reaching a single-atom detection efficiency of 66%. It consists of a tapered lensed single-mode fiber for precise delivery of excitation light and a multi-mode fiber to collect the fluorescence. The fibers are mounted in lithographically defined holding structures on the atom chip. Neutral 87Rb atoms propagating freely in a magnetic guide are detected and the noise of their fluorescence emission is analyzed. The variance of the photon distribution allows us to determine the number of detected photons per atom and from there the atom detection efficiency. The second-order intensity correlation function of the fluorescence shows near-perfect photon anti-bunching and signs of damped Rabi oscillations. With simple improvements, one can increase the detection efficiency to 95%.

  15. Room 103, transom woodwork and original clock. All clocks are ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Room 103, transom woodwork and original clock. All clocks are driven by a common signal. - San Bernardino Valley College, Life Science Building, 701 South Mount Vernon Avenue, San Bernardino, San Bernardino County, CA

  16. Small Mercury Ion Clock for On-board Spacecraft Navigation

    NASA Technical Reports Server (NTRS)

    Prestage, John D.; Chung, Sang; Le, Thanh; Hamell, R.; Maleki, Lute; Tjoelker, Robert

    2004-01-01

    I.Small Ion Clock Approach and Heritage: a) No lasers, uwave cavities, cryogenics, atomic beams, etc. b) Ions are electrically shuttled between separate optical and microwave traps. II. Each trap is optimized for its task: quadrupole for optical state selection; multi-pole for microwave clock. a) Very good stability shown in USNO. Timescale running "open loop." III. "Open loop" operation means no self-measurements of frequency offsets: (Zeeman, ion temperature,... etc.) a) Fewer parts and procedures, produces stable output continuously. IV. Ion clock is not so sensitive to temperature fluctuations a) Measured u:nshielded temperature coefficient of few 10(exp -15) per C. b) No bulky temperature isolation needed.

  17. Detection of weak frequency jumps for GNSS onboard clocks.

    PubMed

    Huang, Xinming; Gong, Hang; Ou, Gang

    2014-05-01

    In this paper, a weak frequency jump detection method is developed for onboard clocks in global navigation satellite systems (GNSS). A Kalman filter is employed to facilitate the onboard real-time processing of atomic clock measurements, whose N-step prediction residuals are used to construct the weak frequency jump detector. Numerical simulations show that the method can successfully detect weak frequency jumps. The detection method proposed in this paper is helpful for autonomous integrity monitoring of GNSS satellite clocks, and can also be applied to other frequency anomalies with an appropriately modified detector. PMID:24802723

  18. Millisecond pulsars - Nature's most stable clocks

    NASA Astrophysics Data System (ADS)

    Taylor, Joseph H., Jr.

    1991-07-01

    The author describes the role pulsars might play in time and frequency technology. Millisecond pulsars are rapidly rotating neutron stars: spherical flywheels some 20 km in diameter, 1.4 times as massive as the Sun, and spinning as fast as several thousand radians per second. Radio noise generated in a pulsar's magnetosphere by a highly beamed process is detectable over interstellar distances, as a periodic sequence of pulses similar to the ticks of an excellent clock. High-precision comparisons between pulsar time and terrestrial atomic time show that over intervals of several years, some millisecond pulsars have fractional stabilities comparable to those of the best atomic clocks. The author briefly reviews the physics of pulsars, discusses the techniques of pulsar timing measurements, and summarizes the results of careful studies of pulsar stabilities.

  19. Storage, transportation, and atomization of CWF for residential applications

    SciTech Connect

    Grimanis, M.P.; Breault, R.W.

    1991-06-01

    The properties and behavior with regard to handling, storage, and atomization in small-scale applications of different coal-water fuels (CWFs) prepared from different parent coals and various beneficiation techniques, were investigated. The CWFs that were prepared included Upper Elkhorn No. 3, Illinois No. 6, and Upper Wyodak coal cleaned by heavy media separation. Also, several CWFs were prepared with Upper Elkhorn No. 3 coal cleaned by heavy media separation with filtration, chemical cleaning, oil agglomeration, and froth flotation. Pressure drop measurements in tubes and viscometer measurements were used to construct rheograms of the seven CWFs that were prepared for shear rates up to 1000 1/s. Analysis of each CWF included proximate, ultimate and ash fusion temperatures. A fully automatic demonstration storage facility was designed and fabricated. The viscosity at higher shear rates (150,000 1/s) will be measured in a capillary viscometer to determine the viscosity at shear rate typically obtained with atomizers. The demonstration storage/handling facility will be tested. A cost analysis of a residential facility will be conducted. The seven CWFs will be burned in the residential combustor developed by Tecogen under contract DE-AC22-87PC79650. 41 figs., 12 tabs.

  20. Topics in atomic hydrogen standard research and applications

    NASA Technical Reports Server (NTRS)

    Peters, H. E.

    1971-01-01

    Hydrogen maser based frequency and time standards have been in continuous use at NASA tracking stations since February 1970, while laboratory work at Goddard has continued in the further development and improvement of hydrogen masers. Concurrently, experimental work has been in progress with a new frequency standard based upon the hydrogen atom using the molecular beam magnetic resonance method. Much of the hydrogen maser technology is directly applicable to the new hydrogen beam standard, and calculations based upon realistic data indicate that the accuracy potential of the hydrogen atomic beam exceeds that of either the cesium beam tube or the hydrogen maser, possibly by several orders of magnitude. In addition, with successful development, the hydrogen beam standard will have several other performance advantages over other devices, particularly exceptional stability and long continuous operating life. Experimental work with a new laboratory hydrogen beam device has recently resulted in the first resonance transition curves, measurements of relative state populations, beam intensities, etc. The most important aspects of both the hydrogen maser and the hydrogen beam work are covered.

  1. Cancellation of the Collisional Frequency Shift in Caesium Fountain Clocks

    SciTech Connect

    Szymaniec, K.; Chalupczak, W.; Tiesinga, E.; Williams, C. J.; Weyers, S.; Wynands, R.

    2007-04-13

    We have observed that the collisional frequency shift in primary caesium fountain clocks varies with the clock state population composition and, in particular, is zero for a given fraction of the |F=4,m{sub F}=0> atoms, depending on the initial cloud parameters. We present a theoretical model explaining our observations. The possibility of the collisional shift cancellation implies an improvement in the performance of caesium fountain standards and a simplification in their operation.

  2. A mercury optical lattice clock at LNE-SYRTE

    NASA Astrophysics Data System (ADS)

    De Sarlo, L.; Favier, M.; Tyumenev, R.; Bize, S.

    2016-06-01

    We describe the development of an optical lattice clock based on mercury and the results obtained since the 7 th SFSM. We briefly present a new solution for the cooling laser system and an improved lattice trap that allows us to interrogate a few thousand atoms in parallel. This translates into a fractional short term stability of 1.2 x 10-15 at the clock frequency of 1.129 PHz.

  3. A transportable optical lattice clock using 171Yb

    NASA Astrophysics Data System (ADS)

    Mura, Gregor; SOC2 Team

    2013-07-01

    We present first results on the spectroscopy of the 1S0 - 3P0 transition at 578nm in a transportable 171Yb optical lattice clock. With the Yb atoms confined in a one-dimensional optical lattice, we have observed linewidths below 200 Hz, limited by saturation broadening. Currently the system is being upgraded towards full clock operation and use of more compact and robust subsystems.

  4. A breadboard of optically-pumped atomic-beam frequency standard for space applications

    NASA Astrophysics Data System (ADS)

    Berthoud, P.; Ruffieux, R.; Affolderbach, C.; Thomann, P.

    2004-06-01

    Observatoire de Neuchâtel (ON) has recently started breadboarding activities for an Optically-pumped Space Cesium-beam Atomic Resonator in the frame of an ESA-ARTES 5 project. The goal is to demonstrate a frequency stability approaching σy = 1×10-12 τ-1/2 with the simplest optical scheme (a single optical frequency for both the atomic pumping and detection processes). This development constitutes a fundamental step in the general effort to reduce the mass of the on-board clocks, while keeping or even improving its performances. It will take advantage of previous activities at ON in the late '80 and of the latest progresses in the field of tunable and narrow-band laser diodes.

  5. Symmetry preserving optimised effective potential theory (application to atoms)

    NASA Astrophysics Data System (ADS)

    Theophilou, Andreas K.; Papaconstantinou, Petros G.; Glushkov, Vitaly

    2006-02-01

    In this paper, general symmetry properties of physical systems are used in order to produce a mapping of the external potential of a many electron system to its optimized effective potential (OEP). The so derived effective potential is used to calculate the OEP ground state energies and spin orbitals. Applications are made to atoms and ions and the results are compared to those of the exact Hartree-Fock approximation. The relative deviations from the exact HF theory (triangleE/E) are of the order of 10-4. The same holds for molecules. One of the features of the present theory is that the many electron wave functions derived by the present method, transform according to the irreducible representations of the exact states.

  6. Electrocatalysts by atomic layer deposition for fuel cell applications

    DOE PAGESBeta

    Cheng, Niancai; Shao, Yuyan; Liu, Jun; Sun, Xueliang

    2016-01-22

    Here, fuel cells are a promising technology solution for reliable and clean energy because they offer high energy conversion efficiency and low emission of pollutants. However, high cost and insufficient durability are considerable challenges for widespread adoption of polymer electrolyte membrane fuel cells (PEMFCs) in practical applications. Current PEMFCs catalysts have been identified as major contributors to both the high cost and limited durability. Atomic layer deposition (ALD) is emerging as a powerful technique for solving these problems due to its exclusive advantages over other methods. In this review, we summarize recent developments of ALD in PEMFCs with a focusmore » on design of materials for improved catalyst activity and durability. New research directions and future trends have also been discussed.« less

  7. The Applications of Atomic Force Microscopy to Vision Science

    PubMed Central

    Last, Julie A.; Russell, Paul; Nealey, Paul F.

    2010-01-01

    The atomic force microscope (AFM) is widely used in materials science and has found many applications in biological sciences but has been limited in use in vision science. The AFM can be used to image the topography of soft biological materials in their native environments. It can also be used to probe the mechanical properties of cells and extracellular matrices, including their intrinsic elastic modulus and receptor-ligand interactions. In this review, the operation of the AFM is described along with a review of how it has been thus far used in vision science. It is hoped that this review will serve to stimulate vision scientists to consider incorporating AFM as part of their research toolkit. PMID:21123767

  8. Coaxial electrohydrodynamic atomization: microparticles for drug delivery applications.

    PubMed

    Davoodi, Pooya; Feng, Fang; Xu, Qingxing; Yan, Wei-Cheng; Tong, Yen Wah; Srinivasan, M P; Sharma, Vijay Kumar; Wang, Chi-Hwa

    2015-05-10

    As cancer takes its toll on human health and well-being, standard treatment techniques such as chemotherapy and radiotherapy often fall short of ideal solutions. In particular, adverse side effects due to excess dosage and collateral damage to healthy cells as well as poor patient compliance due to multiple administrations continue to pose challenges in cancer treatment. Thus, the development of appropriately engineered drug delivery systems (DDS) for effective, controlled and sustained delivery of drugs is of interest for patient treatment. Moreover, the physiopathological characteristics of tumors play an essential role in the success of cancer treatment. Here, we present an overview of the application of double-walled microparticles for local drug delivery with particular focus on the electrohydrodynamic atomization (EHDA) technique and its fabrication challenges. The review highlights the importance of a combination of experimental data and computational simulations for the design of an optimal delivery system. PMID:25483422

  9. Transitions between the 4 f -core-excited states in Ir16+, Ir17+, and Ir18+ ions for clock applications

    NASA Astrophysics Data System (ADS)

    Safronova, U. I.; Flambaum, V. V.; Safronova, M. S.

    2016-05-01

    Iridium ions near 4 f - 5 s level crossings are the leading candidates for a new type of atomic clocks with a high projected accuracy and a very high sensitivity to the temporal variation of the fine structure constant α. To identify spectra of these ions in experiment accurate calculations of the spectra and electromagnetic transition probabilities should be performed. Properties of the 4 f -core-excited states in Ir16+, Ir17+, and Ir18+ ions are evaluated using relativistic many-body perturbation theory and Hartree-Fock-Relativistic method (COWAN code). We evaluate excitation energies, wavelengths, oscillator strengths, and transition rates. Our large-scale calculations included the following set of configurations: 4f14 5 s , 4f14 5 p , 4f13 5s2 , 4f13 5p2 , 4f13 5 s 5 p , 4f12 5s2 5 p , and 4f12 5 s 5p2 in Pm-like Ir16+ ; 4f14 , 4f13 5 s , 4f13 5 p , 4f12 5s2 , 4f12 5 s 5 p , and 4f12 5p2 in Nd-like Ir17+; and 4f13 , 4f12 5 s , 4f12 5 p , 4f11 5s2 , and 4f11 5 s 5 p in Pr-like Ir18+. The 5 s - 5 p transitions are illustrated by the synthetic spectra in the 180 - 200 Å range. Large contributions of magnetic-dipole transitions to lifetimes of low-lying states in the region 2.5 Ry.

  10. Collisional Losses, Decoherence, and Frequency Shifts in Optical Lattice Clocks with Bosons

    SciTech Connect

    Lisdat, Ch.; Winfred, J. S. R. Vellore; Middelmann, T.; Riehle, F.; Sterr, U.

    2009-08-28

    We have quantified collisional losses, decoherence and the collision shift in a one-dimensional optical lattice clock on the highly forbidden transition {sup 1}S{sub 0}-{sup 3}P{sub 0} at 698 nm with bosonic {sup 88}Sr. We were able to distinguish two loss channels: inelastic collisions between atoms in the upper and lower clock state and atoms in the upper clock state only. Based on the measured coefficients, we determine the operation parameters at which a 1D-lattice clock with {sup 88}Sr shows no degradation due to collisions on the fractional uncertainty level of 10{sup -16}.

  11. A fault-tolerant clock

    NASA Technical Reports Server (NTRS)

    Daley, W. P.; Mckenna, J. F., Jr.

    1973-01-01

    Computers must operate correctly even though one or more of components have failed. Electronic clock has been designed to be insensitive to occurrence of faults; it is substantial advance over any known clock.

  12. Cycle Time Reduction in Trapped Mercury Ion Atomic Frequency Standards

    NASA Technical Reports Server (NTRS)

    Burt, Eric A.; Tjoelker, Robert L.; Taghavi, Shervin

    2011-01-01

    The use of the mercury ion isotope (201)Hg(+) was examined for an atomic clock. Taking advantage of the faster optical pumping time in (201)Hg(+) reduces both the state preparation and the state readout times, thereby decreasing the overall cycle time of the clock and reducing the impact of medium-term LO noise on the performance of the frequency standard. The spectral overlap between the plasma discharge lamp used for (201)Hg(+) state preparation and readout is much larger than that of the lamp used for the more conventional (199)Hg(+). There has been little study of (201)Hg(+) for clock applications (in fact, all trapped ion clock work in mercury has been with (199)Hg(+); however, recently the optical pumping time in (201)Hg(+) has been measured and found to be 0.45 second, or about three times faster than in (199)Hg(+) due largely to the better spectral overlap. This can be used to reduce the overall clock cycle time by over 2 seconds, or up to a factor of 2 improvement. The use of the (201)Hg(+) for an atomic clock is totally new. Most attempts to reduce the impact of LO noise have focused on reducing the interrogation time. In the trapped ion frequency standards built so far at JPL, the optical pumping time is already at its minimum so that no enhancement can be had by shortening it. However, by using (201)Hg(+), this is no longer the case. Furthermore, integrity monitoring, the mechanism that determines whether the clock is functioning normally, cannot happen faster than the clock cycle time. Therefore, a shorter cycle time will enable quicker detection of failure modes and recovery from them.

  13. Tutorial: Clock and Clock Systems Performance Measures

    NASA Technical Reports Server (NTRS)

    Allan, David W.

    1996-01-01

    This tutorial contains basic material - familiar to many. This will be used as a foundation upon which we will build - bringing forth some new material and equations that have been developed especially for this tutorial. These will provide increased understanding toward parameter estimation of clock and clock system's performance. There is a very important International Telecommunications Union (ITU) handbook being prepared at this time which goes much further than this tutorial has time to do. I highly recommend it as an excellent resource document. The final draft is just now being completed, and it should be ready late in 1996. It is an outstanding handbook; Dr. Sydnor proposed to the ITU-R several years ago, and is the editor with my assistance. We have some of the best contributors in the community from around the world who have written the ten chapters in this handbook. The title of the handbook is 'Selection and use of Precise Frequency and Time Systems'. It will be available from the ITU secretariat in Geneva, Switzerland, but NAVTEC Seminars also plans to be a distributor.

  14. Estimating the instability of a composite clock

    NASA Technical Reports Server (NTRS)

    Greenhall, Charles A.

    2004-01-01

    A composite clock created from a local clock ensemble is known by its time offsets from the ensemble clocks. By a geometrical argument, estimate for the instability of the composite clock are calculated from the instabilities of the ensemble clocks, individually and against the composite clock. The method is illustrated by examples using simulated and real ensembles.

  15. Push-Pull Laser-Atomic Oscillator

    NASA Astrophysics Data System (ADS)

    Jau, Y.-Y.; Happer, W.

    2007-11-01

    A vapor of alkali-metal atoms in the external cavity of a semiconductor laser, pumped with a time-independent injection current, can cause the laser to self-modulate at the “field-independent 0-0 frequency” of the atoms. Push-pull optical pumping by the modulated light drives most of the atoms into a coherent superposition of the two atomic sublevels with an azimuthal quantum number m=0. The atoms modulate the optical loss of the cavity at the sharply defined 0-0 hyperfine frequency. As in a maser, the system is not driven by an external source of microwaves, but a very stable microwave signal can be recovered from the modulated light or from the modulated voltage drop across the laser diode. Potential applications for this new phenomenon include atomic clocks, the production of long-lived coherent atomic states, and the generation of coherent optical combs.

  16. Push-Pull Laser-Atomic Oscillator

    SciTech Connect

    Jau, Y.-Y.; Happer, W.

    2007-11-30

    A vapor of alkali-metal atoms in the external cavity of a semiconductor laser, pumped with a time-independent injection current, can cause the laser to self-modulate at the 'field-independent 0-0 frequency' of the atoms. Push-pull optical pumping by the modulated light drives most of the atoms into a coherent superposition of the two atomic sublevels with an azimuthal quantum number m=0. The atoms modulate the optical loss of the cavity at the sharply defined 0-0 hyperfine frequency. As in a maser, the system is not driven by an external source of microwaves, but a very stable microwave signal can be recovered from the modulated light or from the modulated voltage drop across the laser diode. Potential applications for this new phenomenon include atomic clocks, the production of long-lived coherent atomic states, and the generation of coherent optical combs.

  17. The eCDR-PLL, a radiation-tolerant ASIC for clock and data recovery and deterministic phase clock synthesis

    NASA Astrophysics Data System (ADS)

    Leitao, P.; Francisco, R.; Llopart, X.; Tavernier, F.; Baron, S.; Bonacini, S.; Moreira, P.

    2015-03-01

    A radiation-tolerant CDR/PLL ASIC has been developed for the upcoming LHC upgrades, featuring clock Frequency Multiplication (FM) and Clock and Data Recovery (CDR), showing deterministic phase and low jitter. Two FM modes have been implemented: either generating 40, 60, 120 and 240 MHz clock outputs for GBT-FPGA applications or providing 40, 80, 160 and 320 MHz clocks for TTC and e-link applications. The CDR operates with 40, 80, 160 or 320 Mbit/s data rates while always generating clocks at 40, 80, 160 and 320 MHz, regardless of the data rate. All the outputs are phase programmable with a resolution of 195 ps or 260 ps, depending on the selected mode. The ASIC has been designed using radiation-tolerant techniques in a 130 nm CMOS technology and operates at a 1.2 V supply voltage.

  18. Clock Synchronization for Multihop Wireless Sensor Networks

    ERIC Educational Resources Information Center

    Solis Robles, Roberto

    2009-01-01

    In wireless sensor networks, more so generally than in other types of distributed systems, clock synchronization is crucial since by having this service available, several applications such as media access protocols, object tracking, or data fusion, would improve their performance. In this dissertation, we propose a set of algorithms to achieve…

  19. The Exxon rechargeable cells. [solar rechargeable clocks

    NASA Technical Reports Server (NTRS)

    Malachesky, P. A.

    1980-01-01

    The design and performance of ambient temperature secondary cells based on the titanium disulfide cathode are discussed. These limited performance products were developed for microelectronic applications such as solar rechargeable watches and clocks which require low drain rate and do not require many deep cycles.

  20. Alkali--rare gas photodissociation lasers: Applications to laser physics and atom-atom interactions

    NASA Astrophysics Data System (ADS)

    Hewitt, John Darby

    This dissertation describes several experiments in which alkali--rare gas laser systems are utilized as a simple platform with which to isolate and study atom-atom interactions and fundamental physical processes that are ill-understood or have never been investigated previously. Specifically, the minimum allowable energy separation between levels 2 and 3 in a three-level laser system has been investigated experimentally, as have two-photon absorption processes in atomic Rb and Cs.

  1. A Novel Method of Clock Synchronization in Distributed System

    NASA Astrophysics Data System (ADS)

    Li, G.; Niu, M. J.; Cai, Y. S.; Chen, X.; Ren, Y. Q.

    2016-03-01

    Time synchronization plays an important role in application of aircraft flying formation and constellation autonomous navigation, etc. In application of clock synchronization in the network system, it is not always true that each observed node may be interconnected, therefore, it is difficult to achieve time synchronization of network system with high precision in the condition that a certain node can only obtain the measurement information of clock from one of its corresponding neighbors, and cannot obtain from other nodes. According to this special problem, a novel method of high precision time synchronization of network system has been proposed. In this paper, we regard each clock as a node in the network system, and based on different distributed topology definition, the following three control algorithms of time synchronization under three circumstances have been designed: without a master clock (reference clock), with a master clock (reference clock), and with a fixed communication delay in the network system. The validity of the designed clock synchronization protocol has been proved both theoretically and through numerical simulation.

  2. Clock Reaction: Outreach Attraction

    ERIC Educational Resources Information Center

    Carpenter, Yuen-ying; Phillips, Heather A.; Jakubinek, Michael B.

    2010-01-01

    Chemistry students are often introduced to the concept of reaction rates through demonstrations or laboratory activities involving the well-known iodine clock reaction. For example, a laboratory experiment involving thiosulfate as an iodine scavenger is part of the first-year general chemistry laboratory curriculum at Dalhousie University. With…

  3. Narrative Clock Sculptures

    ERIC Educational Resources Information Center

    Popp, Linda

    2005-01-01

    Art teacher Linda Popp and artist H. Ed Smith team up to teach about creating sculptural clocks. This lesson shows how a portrait can be created using various media. Students based projects on someone in their lives they have known for a long time. This sculptural problem was part of a series of portrait and self-portrait lessons with a high…

  4. Ultracold atoms and their applications (Scientific session of the Physical Sciences Division of the Russian Academy of Sciences, 28 October 2015)

    NASA Astrophysics Data System (ADS)

    2016-02-01

    A scientific session of the Physical Sciences Division of the Russian Academy of Sciences (RAS), "Ultracold atoms and their applications", was held in the conference hall of the Lebedev Physical Institute, RAS, on 28 October 2015.The papers collected in this issue were written based on talks given at the session:(1) Vishnyakova G A, Golovizin A A, Kalganova E S, Tregubov D O, Khabarova K Yu (Lebedev Physical Institute, Russian Academy of Sciences, Moscow; Moscow Institute of Physics and Technology (State University), Dolgoprudnyi, Moscow region), Sorokin V N, Sukachev D D, Kolachevsky N N (Lebedev Physical Institute, Russian Academy of Sciences, Moscow) "Ultracold lanthanides: from optical clock to a quantum simulator"; (2) Barmashova T V, Martiyanov K A, Makhalov V B (Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod), Turlapov A V (Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod; Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod) "Fermi liquid to Bose condensate crossover in a two-dimensional ultracold gas experiment"; (3) Taichenachev A V, Yudin V I, Bagayev S N (Institute of Laser Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk; Novosibirsk State University, Novosibirsk) "Ultraprecise optical frequency standards based on ultracold atoms: state of the art and prospects"; (4) Ryabtsev I I, Beterov I I, Tretyakov D B, Entin V M, Yakshina E A (Rzhanov Institute of Semiconductor Physics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk; Novosibirsk State University, Novosibirsk) "Spectroscopy of cold rubidium Rydberg atoms for applications in quantum information". • Ultracold lanthanides: from optical clock to a quantum simulator, G A Vishnyakova, A A Golovizin, E S Kalganova, V N Sorokin, D D Sukachev, D O Tregubov, K Yu Khabarova, N N Kolachevsky Physics-Uspekhi, 2016, Volume 59, Number 2, Pages 168–173 • Fermi liquid-to-Bose condensate crossover in a

  5. A precise clock distribution network for MRPC-based experiments

    NASA Astrophysics Data System (ADS)

    Wang, S.; Cao, P.; Shang, L.; An, Q.

    2016-06-01

    In high energy physics experiments, the MRPC (Multi-Gap Resistive Plate Chamber) detectors are widely used recently which can provide higher-resolution measurement for particle identification. However, the application of MRPC detectors leads to a series of challenges in electronics design with large number of front-end electronic channels, especially for distributing clock precisely. To deal with these challenges, this paper presents a universal scheme of clock transmission network for MRPC-based experiments with advantages of both precise clock distribution and global command synchronization. For precise clock distributing, the clock network is designed into a tree architecture with two stages: the first one has a point-to-multipoint long range bidirectional distribution with optical channels and the second one has a fan-out structure with copper link inside readout crates. To guarantee the precision of clock frequency or phase, the r-PTP (reduced Precision Time Protocol) and the DDMTD (digital Dual Mixer Time Difference) methods are used for frequency synthesis, phase measurement and adjustment, which is implemented by FPGA (Field Programmable Gate Array) in real-time. In addition, to synchronize global command execution, based upon this clock distribution network, synchronous signals are coded with clock for transmission. With technique of encoding/decoding and clock data recovery, signals such as global triggers or system control commands, can be distributed to all front-end channels synchronously, which greatly simplifies the system design. The experimental results show that both the clock jitter (RMS) and the clock skew can be less than 100 ps.

  6. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    Not Available

    1994-12-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 204 citations and includes a subject term index and title list.)

  7. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS bibliographic database). Published Search

    SciTech Connect

    1994-02-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles cover sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Citations discuss applications in high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains a minimum of 185 citations and includes a subject term index and title list.)

  8. Laser cooling and trapping of atomic particles. (Latest citations from the NTIS data base). Published Search

    SciTech Connect

    Not Available

    1992-04-01

    The bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps of very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications for high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion are examined. (Contains a minimum of 151 citations and includes a subject term index and title list.)

  9. A New Trapped Ion Clock Based on Hg-201(+)

    NASA Technical Reports Server (NTRS)

    Taghavi-Larigani, S.; Burt, E. A.; Lea, S. N.; Prestage, J. D.; Tjoelker, R. L.

    2009-01-01

    There are two stable odd isotopes of mercury with singly ionized hyperfine structure suitable for a microwave clock: Hg-199(+) and Hg-201(+). Virtually all trapped mercury ion clocks to date have used the 199 isotope. We have begun to investigate the viability of a trapped ion clock based on Hg-201(+). We have measured the unperturbed frequency of the (S-2)(sub 1/2) F = 1, m(sub F) = 0 to (S-2)(sub 1/2) F = 2, m(sub F) = 0 clock transition to be 29.9543658211(2) GHz. In this paper we describe initial measurements with Hg-201(+) and new applications to clocks and fundamental physics.

  10. Clock Synchronization in Wireless Sensor Networks: An Overview

    PubMed Central

    Rhee, Ill-Keun; Lee, Jaehan; Kim, Jangsub; Serpedin, Erchin; Wu, Yik-Chung

    2009-01-01

    The development of tiny, low-cost, low-power and multifunctional sensor nodes equipped with sensing, data processing, and communicating components, have been made possible by the recent advances in micro-electro-mechanical systems (MEMS) technology. Wireless sensor networks (WSNs) assume a collection of such tiny sensing devices connected wirelessly and which are used to observe and monitor a variety of phenomena in the real physical world. Many applications based on these WSNs assume local clocks at each sensor node that need to be synchronized to a common notion of time. This paper reviews the existing clock synchronization protocols for WSNs and the methods of estimating clock offset and clock skew in the most representative clock synchronization protocols for WSNs. PMID:22389588

  11. Progress Towards a Compact Optical Clock at JPL

    NASA Astrophysics Data System (ADS)

    Sullivan, Scott; Rellergert, Wade; Grudinin, Ivan; Baumgartel, Lukas; Yu, Nan

    2014-05-01

    The unprecedented stability and accuracy provided by optical clocks allows improved navigation and planetary science in space applications as well as more precise tests of fundamental laws of physics. However, technological advances towards the miniaturization of the physical volume and reduced power consumption of these clocks must be made to suit space-based application. We will describe JPL's effort towards the development of a compact, low-power optical clock based on 171Yb+. This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. Partial support from NASA Fundamental Physics Program is acknowledged.

  12. Stable Kalman filters for processing clock measurement data

    NASA Technical Reports Server (NTRS)

    Clements, P. A.; Gibbs, B. P.; Vandergraft, J. S.

    1989-01-01

    Kalman filters have been used for some time to process clock measurement data. Due to instabilities in the standard Kalman filter algorithms, the results have been unreliable and difficult to obtain. During the past several years, stable forms of the Kalman filter have been developed, implemented, and used in many diverse applications. These algorithms, while algebraically equivalent to the standard Kalman filter, exhibit excellent numerical properties. Two of these stable algorithms, the Upper triangular-Diagonal (UD) filter and the Square Root Information Filter (SRIF), have been implemented to replace the standard Kalman filter used to process data from the Deep Space Network (DSN) hydrogen maser clocks. The data are time offsets between the clocks in the DSN, the timescale at the National Institute of Standards and Technology (NIST), and two geographically intermediate clocks. The measurements are made by using the GPS navigation satellites in mutual view between clocks. The filter programs allow the user to easily modify the clock models, the GPS satellite dependent biases, and the random noise levels in order to compare different modeling assumptions. The results of this study show the usefulness of such software for processing clock data. The UD filter is indeed a stable, efficient, and flexible method for obtaining optimal estimates of clock offsets, offset rates, and drift rates. A brief overview of the UD filter is also given.

  13. Analytical evaluation of atomic form factors: Application to Rayleigh scattering

    SciTech Connect

    Safari, L.; Santos, J. P.; Amaro, P.; Jänkälä, K.; Fratini, F.

    2015-05-15

    Atomic form factors are widely used for the characterization of targets and specimens, from crystallography to biology. By using recent mathematical results, here we derive an analytical expression for the atomic form factor within the independent particle model constructed from nonrelativistic screened hydrogenic wave functions. The range of validity of this analytical expression is checked by comparing the analytically obtained form factors with the ones obtained within the Hartee-Fock method. As an example, we apply our analytical expression for the atomic form factor to evaluate the differential cross section for Rayleigh scattering off neutral atoms.

  14. An optical lattice clock with accuracy and stability at the 10(-18) level.

    PubMed

    Bloom, B J; Nicholson, T L; Williams, J R; Campbell, S L; Bishof, M; Zhang, X; Zhang, W; Bromley, S L; Ye, J

    2014-02-01

    Progress in atomic, optical and quantum science has led to rapid improvements in atomic clocks. At the same time, atomic clock research has helped to advance the frontiers of science, affecting both fundamental and applied research. The ability to control quantum states of individual atoms and photons is central to quantum information science and precision measurement, and optical clocks based on single ions have achieved the lowest systematic uncertainty of any frequency standard. Although many-atom lattice clocks have shown advantages in measurement precision over trapped-ion clocks, their accuracy has remained 16 times worse. Here we demonstrate a many-atom system that achieves an accuracy of 6.4 × 10(-18), which is not only better than a single-ion-based clock, but also reduces the required measurement time by two orders of magnitude. By systematically evaluating all known sources of uncertainty, including in situ monitoring of the blackbody radiation environment, we improve the accuracy of optical lattice clocks by a factor of 22. This single clock has simultaneously achieved the best known performance in the key characteristics necessary for consideration as a primary standard-stability and accuracy. More stable and accurate atomic clocks will benefit a wide range of fields, such as the realization and distribution of SI units, the search for time variation of fundamental constants, clock-based geodesy and other precision tests of the fundamental laws of nature. This work also connects to the development of quantum sensors and many-body quantum state engineering (such as spin squeezing) to advance measurement precision beyond the standard quantum limit. PMID:24463513

  15. Science 101: How Do Atomic Clocks Work?

    ERIC Educational Resources Information Center

    Science and Children, 2008

    2008-01-01

    You might be wondering why in the world we need such precise measures of time. Well, many systems we use everyday, such as Global Positioning Systems, require precise synchronization of time. This comes into play in telecommunications and wireless communications, also. For purely scientific reasons, we can use precise measurement of time to…

  16. Chromatic dispersion induced PM-AM conversion and its application in the all-optical clock recovery of NRZ-DPSK signals

    NASA Astrophysics Data System (ADS)

    Tang, Ming; Fu, Songnian; Zhong, Wen-de; Wen, Yang Jing; Shum, Ping

    2007-11-01

    We investigated the property of conversion between phase modulation (PM) and amplitude modulation (AM) in optical fiber transmission link due to chromatic dispersion (CD) for the purpose of clock information generation. As a result, a novel all-optical clock recovery (CR) scheme from 10 Gbps non-return-to-zero differential phase-shift-keying (NRZ-DPSK) signal has been demonstrated experimentally. We introduce a chromatic dispersion induced clock tone from the NRZ-DPSK signal and feed it into a free-running semiconductor optical amplifier (SOA) based fiber ring laser to achieve an injection mode-locking. The generated mode-locked pulse is the corresponding regenerated clock of the original signal. Since no special component is required for NRZ-DPSK demodulation, our proposed method is very promising because of its simple configuration and higher stability. In experiments, 20km standard single mode fiber is employed to accumulate CD and generate PM-AM conversion hence regenerate clock tone of the NRZ-DPSK signal. The recovered clock signal with the extinction ratio over 15 dB and the root-mean-square timing jitter of 720 fs is achieved under 2 31-1 pseudorandom binary sequence NRZ-DPSK signals measurement. We also demonstrated a similar CR system by using a chirped fiber Bragg grating (CFBG) as the dispersion device. With the same operation principle, it is quite convenient and promising to extend our configuration to implement all-optical CR for NRZ-DPSK signal with data rate up to 40Gbps.

  17. N+CPT clock resonance

    SciTech Connect

    Crescimanno, M.; Hohensee, M.

    2008-12-15

    In a typical compact atomic time standard a current modulated semiconductor laser is used to create the optical fields that interrogate the atomic hyperfine transition. A pair of optical sidebands created by modulating the diode laser become the coherent population trapping (CPT) fields. At the same time, other pairs of optical sidebands may contribute to other multiphoton resonances, such as three-photon N-resonance [Phys. Rev. A 65, 043817 (2002)]. We analyze the resulting joint CPT and N-resonance (hereafter N+CPT) analytically and numerically. Analytically we solve a four-level quantum optics model for this joint resonance and perturbatively include the leading ac Stark effects from the five largest optical fields in the laser's modulation comb. Numerically we use a truncated Floquet solving routine that first symbolically develops the optical Bloch equations to a prescribed order of perturbation theory before evaluating. This numerical approach has, as input, the complete physical details of the first two excited-state manifolds of {sup 87}Rb. We test these theoretical approaches with experiments by characterizing the optimal clock operating regimes.

  18. Clocks in algae.

    PubMed

    Noordally, Zeenat B; Millar, Andrew J

    2015-01-20

    As major contributors to global oxygen levels and producers of fatty acids, carotenoids, sterols, and phycocolloids, algae have significant ecological and commercial roles. Early algal models have contributed much to our understanding of circadian clocks at physiological and biochemical levels. The genetic and molecular approaches that identified clock components in other taxa have not been as widely applied to algae. We review results from seven species: the chlorophytes Chlamydomonas reinhardtii, Ostreococcus tauri, and Acetabularia spp.; the dinoflagellates Lingulodinium polyedrum and Symbiodinium spp.; the euglenozoa Euglena gracilis; and the red alga Cyanidioschyzon merolae. The relative simplicity, experimental tractability, and ecological and evolutionary diversity of algal systems may now make them particularly useful in integrating quantitative data from "omic" technologies (e.g., genomics, transcriptomics, metabolomics, and proteomics) with computational and mathematical methods. PMID:25379817

  19. Direct drive rotary atomization for dry flue gas desulfurization applications

    SciTech Connect

    Martinelli, R.; Elwell, R.C.

    1986-01-01

    General Electric Environmental Services, Inc. (GEESI) and APV Anhydro A/S (Anhydro) have chosen the direct drive approach for atomizers rated at 200 HP and above. This approach was selected to increase component life, improve reliability and reduce power transmission losses which are encountered in conventional gear-driven units. As an added benefit, the use of a variable frequency drive simplified atomizer speed changes, and provides lower inrush current than required with a conventional starter. This paper presents design and production considerations, laboratory tests results, and field experience with the GEESI variable speed, direct drive atomizer system. Data is presented on atomized droplet size characterization, power consumption, rotor vibration, bearing temperatures, and motor performance at various liquid flow rates and atomizer rotating speeds.

  20. Applications of AFM for atomic manipulation and spectroscopy

    NASA Astrophysics Data System (ADS)

    Custance, Oscar

    2009-03-01

    Since the first demonstration of atom-by-atom assembly [1], atomic manipulation with scanning tunneling microscopy has yielded stunning realizations in nanoscience. A new exciting panorama has been recently opened with the possibility of manipulating atoms at surfaces using atomic force microscopy (AFM) [2-5]. In this talk, we will present two different approaches that enable patterning structures at semiconductor surfaces by manipulating individual atoms with AFM and at room temperature [2, 3]. We will discuss the physics behind each protocol through the analysis of the measured forces associated with these manipulations [3-5]. Another challenging issue in scanning probe microscopy is the ability to disclose the local chemical composition of a multi-element system at atomic level. Here, we will introduce a single-atom chemical identification method, which is based on detecting the forces between the outermost atom of the AFM tip and the atoms at a surface [6]. We demonstrate this identification procedure on a particularly challenging system, where any discrimination attempt based solely on topographic measurements would be impossible to achieve. [4pt] References: [0pt] [1] D. M. Eigler and E. K. Schweizer, Nature 344, 524 (1990); [0pt] [2] Y. Sugimoto, M. Abe, S. Hirayama, N. Oyabu, O. Custance and S. Morita, Nature Materials 4, 156 (2005); [0pt] [3] Y. Sugimoto, P. Pou, O. Custance, P. Jelinek, M. Abe, R. Perez and S. Morita, Science 322, 413 (2008); [0pt] [4] Y. Sugimoto, P. Jelinek, P. Pou, M. Abe, S. Morita, R. Perez and O. Custance, Phys. Rev. Lett. 98, 106104 (2007); [0pt] [5] M. Ternes, C. P. Lutz, C. F. Hirjibehedin, F. J. Giessibl and A. J. Heinrich, Science 319, 1066 (2008); [0pt] [6] Y. Sugimoto, P. Pou, M. Abe, P. Jelinek, R. Perez, S. Morita, and O. Custance, Nature 446, 64 (2007)

  1. 229Th the Bridge Between Nuclear and Atomic Interactions

    SciTech Connect

    Burke, J T; Casperson, R J; Swanberg, E L; Thomas, D

    2010-12-02

    The precise measurement of time has been a goal of physicists for centuries. With every new increase in our ability to measure time we have discovered new phenomena. The most advanced clocks available to us currently are atomic clocks that use electronic transitions to track the passage of time. In this proposal, I put forward the framework for the first nuclear clock estimated to be 1000 to 10000 times more precise than the current atomic clocks. This research will explore in detail the atomic nuclear interactions and help perfect and refine current atomic-nuclear interaction models. The realization of a {sup 229}Th nuclear clock will allow tests of cosmology by measuring the change of the fine structure constant as a function of time. The results of these experiments could dramatically alter our view of the universe, its past and future evolution. Precision clocks - with fundamental physics applications - require a long-lived quantum transition (two-level system) that is immune to external perturbations. Nuclear transitions would be better suited than atomic transitions for these applications except that nuclear transitions are typically much higher in energy and therefore cannot be accessed with table-top lasers. There is, however, one promising nuclear transition: the doublet between the ground and first excited states of the {sup 229}Th nucleus discovered by Helmer and Reich. This doublet has an energy splitting of 7.6 {+-} 0.5 eV, a spin difference of 1 h-bar, and an excited state half-life that could be as long as hours. A precision clock based on the {sup 229}Th nuclear doublet has been proposed by Peik et al. Their design is similar to the ion clock research being conducted at NIST in Boulder, CO. However, the NIST researchers use atomic transitions for their frequency standards. In the {sup 229}Th nuclear doublet transition is the frequency standard while atomic transitions are used to cool the ions and for probing the state of the {sup 229}Th nucleus

  2. Stochastic modeling of high-stability ground clocks in GPS analysis

    NASA Astrophysics Data System (ADS)

    Wang, Kan; Rothacher, Markus

    2013-05-01

    In current global positioning system (GPS) applications, receiver clocks are typically estimated epoch-wise in the data analyses even for clocks with high performance like Hydrogen-masers (H-maser). Applying an appropriate clock model for high-stability receiver clocks should, in view of the strong correlation between the station height and the clock parameters, significantly improve the positioning results. Recent experiments have shown that modeling the deterministic behavior of high-quality receiver clocks can improve the kinematic precise point positioning considerably. In this paper, well-behaving ground clocks are studied in detail applying constraints between subsequent and near-subsequent clock parameters. The influence of different weights for these relative clock constraints on the positioning quality, especially on the height, is investigated. For excellent clocks, an improvement of up to a factor of 3 can be obtained for the repeatability of the kinematic height estimates. This may be essential to detect small but sudden changes in the vertical component (e.g., caused by earthquakes). Troposphere zenith path delays (ZPD) are also heavily correlated with the receiver clock estimates and station heights. All these parameters are usually estimated simultaneously. We show that the use of relative clock constraints allows for a higher time resolution of the ZPD estimates (smaller than 2 h) without compromising the quality of the kinematic height estimates.

  3. Clock synchronization of a large multiprocessor system in the presence of malicious faults

    NASA Technical Reports Server (NTRS)

    Shin, Kang G.; Ramanathan, P.

    1987-01-01

    An interconnection algorithm is presented for achieving clock synchronization in a multiprocessor system. The system is assumed to be maliciously faulty, i.e., some processors are out of synchronization and lie about their clock state to other intragroup or intergroup processors. A phase-locked clock network design is proposed which groups the clocks in the system into diverse clusters. The clusters are then treated as single clock units from the perspective of the network. The algorithm minimizes the number of interconnections while permitting synchronization of large multiprocessor systems controlling time-critical applications such as aircraft, nuclear reactors and industrial processes.

  4. RACE: A High Performance Clock for the ISS

    NASA Astrophysics Data System (ADS)

    Gibble, K.; Fertig, C.; Li, R.; Klipstein, W.; Prestage, J.; Seidel, D.; Thompson, R.

    RACE, the Rubidium Atomic Clock Experiment, is a clock experiment that may fly on the International Space Station. The principle advantage of microgravity for laser-cooled atomic clocks is a long interrogation time. In a microgravity clock, the interrogation time may be as long as 10 s, which correspond to a transition linewidth of 50 mHz. We expect the long interrogation time may allow accuracies approaching 10t17 for RACE. To achieve the high accuracy, a high short-term stability is very advantageous. RACE is based on 87Rb because it has a cold collision frequency shift 50 times smaller than that for Cesium. This allows a much higher density and therefore a higher short-term stability. Our design goals include achieving a high short-term stability as well as minimizing the demands on the local oscillator. Solutions to these problems include multiply launching atoms, or juggling, to retain a high throughput, and a continuous probing of the local oscillator. We will discuss the design and performance goals, potential tests of relativity and fundamental physics, and the importance of clocks for space navigation.

  5. Systematic Study of the ^87Sr Clock Transition in an Optical Lattice

    NASA Astrophysics Data System (ADS)

    Boyd, Martin; Ludlow, Andrew; Zelevinsky, Tanya; Foreman, Seth; Blatt, Sebastian; Notcutt, Mark; Ido, Tetsuya; Ye, Jun

    2006-05-01

    The ^1S0-^3P0 transition in ^87Sr is studied for the realization of an optical atomic clock, using μK atoms in a magic wavelength optical lattice [1]. The probe laser frequency is measured with an octave-spanning fs comb, which is referenced to a hydrogen maser (directly calibrated by the NIST primary Cs fountain clock) allowing high precision evaluation of potential systematic frequency shifts . By varying the lattice wavelength and trapping depth we find that the magic wavelength for the clock transition is 813.418(10) with a clock sensitivity to lattice deviations of ˜2 mHz/MHz for lattice intensities of 10 kW/cm^2. To explore the effect of atomic collisions on the clock frequency we varied the atomic density by a factor of 50 and did not find any shifts at the 3 x10-14 level. Dependence of the clock transition on magnetic fields has been examined as the hyperfine interaction (I = 9/2), which provides the small transition moment for the doubly forbidden clock transition, also results in a differential g factor of the ^3P0 and ^1S0 levels. We will report the latest results of this optical clock system. [1] A.D. Ludlow et al., Phys Rev Lett 96, 033003 (2006).

  6. Frequency ratios of optical lattice clocks at the 17th decimal place

    NASA Astrophysics Data System (ADS)

    Katori, Hidetoshi

    2016-05-01

    Optical lattice clocks benefit from a low quantum-projection noise by simultaneously interrogating a large number of atoms, which are trapped in an optical lattice tuned to the ``magic wavelength'' to largely cancel out light shift perturbation in the clock transition. About a thousand atoms enable the clocks to achieve 10-18 instability in a few hours of operation, allowing intensive investigation and control of systematic uncertainties. As optical lattice clocks have reached inaccuracies approaching 10-18, it is now the uncertainty of the SI second (~ 10-16) itself that restricts the measurement of the absolute frequencies of such optical clocks. Direct comparisons of optical clocks are, therefore, the only way to investigate and utilize their superb performance beyond the SI second. In this presentation, we report on frequency comparisons of optical lattice clocks with neutral strontium (87 Sr), ytterbium (171 Yb) and mercury (199 Hg) atoms. By referencing cryogenic Sr clocks, we determine frequency ratios, νYb/νSr and νHg/νSr, of a cryogenic Yb clock and a Hg clock with uncertainty at the mid 10-17 level. Such ratios provide an access to search for temporal variation of the fundamental constants. We also present remote comparisons between cryogenic Sr clocks located at RIKEN and the University of Tokyo over a 30-km-long phase-stabilized fiber link. The gravitational red shift Δν /ν0 ~ 1.1× 10-18 Δh cm-1 reads out the height difference of Δh ~ 15 m between the two clocks with uncertainty of 5 cm, which demonstrates a step towards relativistic geodesy. ERATO, JST.

  7. Circadian Clock, Cancer, and Chemotherapy

    PubMed Central

    2015-01-01

    The circadian clock is a global regulatory system that interfaces with most other regulatory systems and pathways in mammalian organisms. Investigations of the circadian clock–DNA damage response connections have revealed that nucleotide excision repair, DNA damage checkpoints, and apoptosis are appreciably influenced by the clock. Although several epidemiological studies in humans and a limited number of genetic studies in mouse model systems have indicated that clock disruption may predispose mammals to cancer, well-controlled genetic studies in mice have not supported the commonly held view that circadian clock disruption is a cancer risk factor. In fact, in the appropriate genetic background, clock disruption may instead aid in cancer regression by promoting intrinsic and extrinsic apoptosis. Finally, the clock may affect the efficacy of cancer treatment (chronochemotherapy) by modulating the pharmacokinetics and pharmacodynamics of chemotherapeutic drugs as well as the activity of the DNA repair enzymes that repair the DNA damage caused by anticancer drugs. PMID:25302769

  8. Huygens synchronization of two clocks

    PubMed Central

    Oliveira, Henrique M.; Melo, Luís V.

    2015-01-01

    The synchronization of two pendulum clocks hanging from a wall was first observed by Huygens during the XVII century. This type of synchronization is observed in other areas, and is fundamentally different from the problem of two clocks hanging from a moveable base. We present a model explaining the phase opposition synchronization of two pendulum clocks in those conditions. The predicted behaviour is observed experimentally, validating the model. PMID:26204557

  9. A mixed relaxed clock model.

    PubMed

    Lartillot, Nicolas; Phillips, Matthew J; Ronquist, Fredrik

    2016-07-19

    Over recent years, several alternative relaxed clock models have been proposed in the context of Bayesian dating. These models fall in two distinct categories: uncorrelated and autocorrelated across branches. The choice between these two classes of relaxed clocks is still an open question. More fundamentally, the true process of rate variation may have both long-term trends and short-term fluctuations, suggesting that more sophisticated clock models unfolding over multiple time scales should ultimately be developed. Here, a mixed relaxed clock model is introduced, which can be mechanistically interpreted as a rate variation process undergoing short-term fluctuations on the top of Brownian long-term trends. Statistically, this mixed clock represents an alternative solution to the problem of choosing between autocorrelated and uncorrelated relaxed clocks, by proposing instead to combine their respective merits. Fitting this model on a dataset of 105 placental mammals, using both node-dating and tip-dating approaches, suggests that the two pure clocks, Brownian and white noise, are rejected in favour of a mixed model with approximately equal contributions for its uncorrelated and autocorrelated components. The tip-dating analysis is particularly sensitive to the choice of the relaxed clock model. In this context, the classical pure Brownian relaxed clock appears to be overly rigid, leading to biases in divergence time estimation. By contrast, the use of a mixed clock leads to more recent and more reasonable estimates for the crown ages of placental orders and superorders. Altogether, the mixed clock introduced here represents a first step towards empirically more adequate models of the patterns of rate variation across phylogenetic trees.This article is part of the themed issue 'Dating species divergences using rocks and clocks'. PMID:27325829

  10. The Vitamin C Clock Reaction

    NASA Astrophysics Data System (ADS)

    Wright, Stephen W.

    2002-01-01

    An iodine clock reaction that gives a colorless to black result similar to that of the familiar Landolt iodate-bisulfite clock reaction is described. The vitamin C clock reaction uses chemicals that are readily available on the retail market: vitamin C, tincture of iodine, 3% hydrogen peroxide, and laundry starch. Orange juice may be used as the vitamin C source to give an orange to black reaction.

  11. Huygens synchronization of two clocks.

    PubMed

    Oliveira, Henrique M; Melo, Luís V

    2015-01-01

    The synchronization of two pendulum clocks hanging from a wall was first observed by Huygens during the XVII century. This type of synchronization is observed in other areas, and is fundamentally different from the problem of two clocks hanging from a moveable base. We present a model explaining the phase opposition synchronization of two pendulum clocks in those conditions. The predicted behaviour is observed experimentally, validating the model. PMID:26204557

  12. Low-power, miniature {sup 171}Yb ion clock using an ultra-small vacuum package

    SciTech Connect

    Jau, Y.-Y.; Schwindt, P. D. D.; Partner, H.; Prestage, J. D.; Kellogg, J. R.; Yu, N.

    2012-12-17

    We report a demonstration of a very small microwave atomic clock using the 12.6 GHz hyperfine transition of the trapped {sup 171}Yb ions inside a miniature, completely sealed-off 3 cm{sup 3} ion-trap vacuum package. In the ion clock system, all of the components are highly miniaturized with low power consumption except the 369 nm optical pumping laser still under development for miniaturization. The entire clock, including the control electronics, consumes <300 mW. The fractional frequency instability of the miniature Yb{sup +} clock reaches the 10{sup -14} range after a few days of integration.

  13. European plans for new clocks in space

    NASA Technical Reports Server (NTRS)

    Leschiutta, Sigfrido M.; Tavella, Patrizia

    1995-01-01

    An outline of the future European space research program where precise clocks are necessary is presented, pointing out how space applications are posing impressive requirements as regards clock mass, power, ruggedness, long life, accuracy and, in some cases, spectral purity. The material presented was gathered in some laboratories; useful information was obtained from the Space Agencies of France (CNES), Germany (DARA) and Italy (ASI), but the bulk is coming from a recent exercise promoted inside ESA (the European Space Agency) and aimed to prefigure space research activities at the beginning of the next millennium. This exercise was called Horizon 2000 plus; the outcomings were summarized in two reports, presented by ESA in may 1994. Precise clocks and time measurements are needed not only for deep-space or out-ward space missions, but are essential tools also for Earth oriented activities. In this latter field, the European views and needs were discussed in October 1994, in a meeting organized by ESA and devoted to Earth Observation problems. By a scrutiny of these reports, an analysis was performed on the missions requiring a precise clock on board and the driving requirements were pointed out, leading to a survey of the necessary PTTI developments that, to some extent, are in the realm of possibility but that pose serious challenges. In this report the use of frequency standards in the satellite navigation systems is not considered.

  14. Spaceborne clock system: Some alternatives for a proposed NASA experiment

    NASA Technical Reports Server (NTRS)

    Beehler, R. E.

    1971-01-01

    A spaceborne clock experiment is proposed with the objectives of improving international time and frequency comparisons, studying precise one-way Doppler tracking and one-way ranging techniques, performing relativistic studies, and developing new atomic frequency standards technology. Various alternatives are considered for accomplishing these goals, including the use of existing satellite and earth-based time dissemination systems as well as the development of a new frequency standard for this specific application. One conclusion is that several attractive alternatives already exist for meeting the goal of improved time and frequency dissemination. However, to achieve all the other 4 goals at the NASA-stated levels of accuracy, a spaceborne atomic frequency standard may be required. An analysis of achievements to date with quartz oscillators, rubidium standards, cesium beam standards, hydrogen masers, and several other possibilities leads to the conclusion that cesium and rubidium standards offer the best choices for the experiment as proposed by NASA. The greatest obstacle to a spaceborne atomic standard appears to be its electrical power requirements.

  15. Spin-orbit coupling in a strontium optical lattice clock

    NASA Astrophysics Data System (ADS)

    Bothwell, Tobias; Bromley, Sarah; Kolkowitz, Shimon; Zhang, Xibo; Wall, Michael; Rey, Ana Maria; Ye, Jun

    2016-05-01

    Synthetic gauge fields are a promising tool for creating complex Hamiltonians with ultracold neutral atoms that may mimic the fractional Quantum Hall effect and other topological states. A promising approach is to use spin-orbit coupling to treat an internal degree of freedom as an effective `synthetic' spatial dimension. Here, this synthetic dimension is comprised by the internal ground and excited states used for high-precision clock spectroscopy in a fermionic strontium optical lattice clock. We report on our progress towards this goal in a system where atoms tunnel through a 1D optical lattice during clock interrogation. We present measurements of the lattice band structure under varying Lamb-Dicke parameters and in a regime where s-wave collisions are expected to contribute density dependent frequency shifts.

  16. Applications of atom interferometry - from ground to space

    NASA Astrophysics Data System (ADS)

    Schubert, Christian; Rasel, Ernst Maria; Gaaloul, Naceur; Ertmer, Wolfgang

    2016-07-01

    Atom interferometry is utilized for the measurement of rotations [1], accelerations [2] and for tests of fundamental physics [3]. In these devices, three laser light pulses separated by a free evolution time coherently manipulate the matter waves which resembles the Mach-Zehnder geometry in optics. Atom gravimeters demonstrated an accuracy of few microgal [2,4], and atom gradiometers showed a noise floor of 30 E Hz^{-1/2} [5]. Further enhancements of atom interferometers are anticipated by the integration of novel source concepts providing ultracold atoms, extending the free fall time of the atoms, and enhanced techniques for coherent manipulation. Sources providing Bose-Einstein condensates recently demontrated a flux compatible with precision experiments [6]. All of these aspects are studied in the transportable quantum gravimeter QG-1 and the very long baseline atom interferometry teststand in Hannover [7] with the goal of surpassing the microgal regime. Going beyond ground based setups, the QUANTUS collaboration exploits the unique features of a microgravity environment in drop tower experiments [8] and in a sounding rocket mission. The payloads are compact and robust atom optics experiments based on atom chips [6], enabling technology for transportable sensors on ground as a byproduct. More prominently, they are pathfinders for proposed satellite missions as tests of the universality of free fall [9] and gradiometry based on atom interferometers [10]. This work is supported by the German Space Agency (DLR) with funds provided by the Federal Ministry for Economic Affairs and Energy (BMWi) due to an enactment of the German Bundestag under grant numbers DLR 50WM1552-1557 (QUANTUS-IV-Fallturm) and by the Deutsche Forschungsgemeinschaft in the framework of the SFB 1128 geo-Q. [1] PRL 114 063002 2015 [2] Nature 400 849 1999 [3] PRL 112 203002 2014 [4] NJP 13 065026 2011 [5] PRA 65 033608 2002 [6] NJP 17 065001 2015 [7] NJP 17 035011 2015 [8] PRL 110 093602 2013 [9

  17. Code-Phase Clock Bias and Frequency Offset in PPP Clock Solutions.

    PubMed

    Defraigne, Pascale; Sleewaegen, Jean-Marie

    2016-07-01

    Precise point positioning (PPP) is a zero-difference single-station technique that has proved to be very effective for time and frequency transfer, enabling the comparison of atomic clocks with a precision of a hundred picoseconds and a one-day stability below the 1e-15 level. It was, however, noted that for some receivers, a frequency difference is observed between the clock solution based on the code measurements and the clock solution based on the carrier-phase measurements. These observations reveal some inconsistency either between the code and carrier phases measured by the receiver or between the data analysis strategy of codes and carrier phases. One explanation for this discrepancy is the time offset that can exist for some receivers between the code and the carrier-phase latching. This paper explains how a code-phase bias in the receiver hardware can induce a frequency difference between the code and the carrier-phase clock solutions. The impact on PPP is then quantified. Finally, the possibility to determine this code-phase bias in the PPP modeling is investigated, and the first results are shown to be inappropriate due to the high level of code noise. PMID:26595916

  18. A high-performance frequency stability compact CPT clock based on a Cs-Ne microcell.

    PubMed

    Boudot, Rodolphe; Liu, Xiaochi; Abbé, Philippe; Chutani, Ravinder; Passilly, Nicolas; Galliou, Serge; Gorecki, Christophe; Giordano, Vincent

    2012-11-01

    This paper reports on a compact table-top Cs clock based on coherent population trapping (CPT) with advanced frequency stability performance. The heart of the clock is a single buffer gas Cs-Ne microfabricated cell. Using a distributed feedback (DFB) laser resonant with the Cs D1 line, the contrast of the CPT signal is found to be maximized around 80°C, a value for which the temperature dependence of the Cs clock frequency is canceled. Advanced techniques are implemented to actively stabilize the clock operation on a zero-light-shift point. The clock frequency stability is measured to be 3.8 × 10(-11) at 1 s and well below 10(-11) until 50,000 s. These results demonstrate the possibility to develop high-performance chip-scale atomic clocks using vapor cells containing a single buffer gas. PMID:23192824

  19. Master/slave clock arrangement for providing reliable clock signal

    NASA Technical Reports Server (NTRS)

    Abbey, Duane L. (Inventor)

    1977-01-01

    The outputs of two like frequency oscillators are combined to form a single reliable clock signal, with one oscillator functioning as a slave under the control of the other to achieve phase coincidence when the master is operative and in a free-running mode when the master is inoperative so that failure of either oscillator produces no effect on the clock signal.

  20. A Light Clock Satisfying the Clock Hypothesis of Special Relativity

    ERIC Educational Resources Information Center

    West, Joseph

    2007-01-01

    The design of the FMEL, a floor-mirrored Einstein-Langevin "light clock", is introduced. The clock provides a physically intuitive manner to calculate and visualize the time dilation effects for a spatially extended set of observers (an accelerated "frame") undergoing unidirectional acceleration or observers on a rotating cylinder of constant…

  1. The Mechanism of the Formaldehyde Clock Reaction.

    ERIC Educational Resources Information Center

    Burnett, M. G.

    1982-01-01

    Provides background information and problems with the formaldehyde clock reaction, including comparisons of experimental clock times reported in the literature and conditions for the reliable use of the formaldehyde clock based on a method discussed. (JN)

  2. Digital processing clock

    NASA Technical Reports Server (NTRS)

    Phillips, D. H.

    1982-01-01

    Tthe digital processing clock SG 1157/U is described. It is compatible with the PTTI world where it can be driven by an external cesium source. Built-in test equipment shows synchronization with cesium through 1 pulse per second. It is built to be expandable to accommodate future time-keeping needs of the Navy as well as any other time ordered functions. Examples of this expandibility are the inclusion of an unmodulated XR3 time code and the 2137 modulate time code (XR3 with 1 kHz carrier).

  3. Methodologies for steering clocks

    NASA Technical Reports Server (NTRS)

    Chadsey, Harold

    1995-01-01

    One of the concerns of the PTTI community is the coordination of one time scale with another. This is accomplished through steering one clock system to another, with a goal of a zero or constant offset in time and frequency. In order to attain this goal, rate differences are calculated and allowed for by the steering algorithm. This paper will present several of these different methods of determining rate differences. Ideally, any change in rate should not cause the offset to change sign (overshoot) by any amount, but certainly not by as much as its previous absolute value. The advantages and disadvantages of each depend on the user's situation.

  4. Einstein’s Clocks

    SciTech Connect

    Lincoln, Don

    2015-09-09

    One of the most non-intuitive physics theories ever devised is Einstein’s Theory of Special Relativity, which claim such crazy-sounding things as two people disagreeing on such familiar concepts as length and time. In this video, Fermilab’s Dr. Don Lincoln shows that every single day particle physicists prove that moving clocks tick more slowly than stationary ones. He uses an easy to understand example of particles that move for far longer distances than you would expect from combining their velocity and stationary lifetime.

  5. Biological switches and clocks

    PubMed Central

    Tyson, John J.; Albert, Reka; Goldbeter, Albert; Ruoff, Peter; Sible, Jill

    2008-01-01

    To introduce this special issue on biological switches and clocks, we review the historical development of mathematical models of bistability and oscillations in chemical reaction networks. In the 1960s and 1970s, these models were limited to well-studied biochemical examples, such as glycolytic oscillations and cyclic AMP signalling. After the molecular genetics revolution of the 1980s, the field of molecular cell biology was thrown wide open to mathematical modellers. We review recent advances in modelling the gene–protein interaction networks that control circadian rhythms, cell cycle progression, signal processing and the design of synthetic gene networks. PMID:18522926

  6. A mixed relaxed clock model

    PubMed Central

    2016-01-01

    Over recent years, several alternative relaxed clock models have been proposed in the context of Bayesian dating. These models fall in two distinct categories: uncorrelated and autocorrelated across branches. The choice between these two classes of relaxed clocks is still an open question. More fundamentally, the true process of rate variation may have both long-term trends and short-term fluctuations, suggesting that more sophisticated clock models unfolding over multiple time scales should ultimately be developed. Here, a mixed relaxed clock model is introduced, which can be mechanistically interpreted as a rate variation process undergoing short-term fluctuations on the top of Brownian long-term trends. Statistically, this mixed clock represents an alternative solution to the problem of choosing between autocorrelated and uncorrelated relaxed clocks, by proposing instead to combine their respective merits. Fitting this model on a dataset of 105 placental mammals, using both node-dating and tip-dating approaches, suggests that the two pure clocks, Brownian and white noise, are rejected in favour of a mixed model with approximately equal contributions for its uncorrelated and autocorrelated components. The tip-dating analysis is particularly sensitive to the choice of the relaxed clock model. In this context, the classical pure Brownian relaxed clock appears to be overly rigid, leading to biases in divergence time estimation. By contrast, the use of a mixed clock leads to more recent and more reasonable estimates for the crown ages of placental orders and superorders. Altogether, the mixed clock introduced here represents a first step towards empirically more adequate models of the patterns of rate variation across phylogenetic trees. This article is part of the themed issue ‘Dating species divergences using rocks and clocks’. PMID:27325829

  7. Automatic minimisation of micromotion in a 88Sr+ optical clock

    NASA Astrophysics Data System (ADS)

    Barwood, G. P.; Huang, G.; Klein, H. A.; Gill, P.

    2015-07-01

    Optical clocks based on narrow linewidth transitions in single cold ions confined in RF traps are being developed at a number of laboratories worldwide. For these ion clock systems, excess micromotion can cause both Stark and Doppler frequency shifts and also a degradation of frequency stability as a result of a reduced excitation rate to the clock transition. At NPL, we detect micromotion in our 88Sr+ optical clocks by observing the correlation between photon arrival times and the zero crossing of the RF trap drive signal. Recently, two nominally identical 88Sr+ optical clocks have been operated over several days and their frequencies compared against one another. During this time the dc voltages on the endcap and compensation voltage electrodes required to minimise the micromotion can change significantly, particularly following the loading of an ion. This paper describes an automatic method to monitor and minimise micromotion applicable to single ion clocks and which we demonstrate using our two NPL 88Sr+ ion clocks.

  8. Decoherence Spectroscopy Theory and Application with an Atom Interferometer

    NASA Astrophysics Data System (ADS)

    Trubko, Raisa; Cronin, Alexander

    2016-05-01

    We developed decoherence spectroscopy as a method to improve the accuracy of a tune-out wavelength (λzero) measurement made with atom interferometry. Specifically, we used atom interference fringe contrast loss as a function of laser frequency in order to monitor Doppler shifts. This was particularly helpful since we used a multi-pass cavity to recycle laser light in this experiment. The resulting decoherence spectra have non-intuitive features. Therefore we present a theoretical model for decoherence spectroscopy and compare this model to several empirical examples.

  9. RAPID COMMUNICATION: Improving prediction accuracy of GPS satellite clocks with periodic variation behaviour

    NASA Astrophysics Data System (ADS)

    Heo, Youn Jeong; Cho, Jeongho; Heo, Moon Beom

    2010-07-01

    The broadcast ephemeris and IGS ultra-rapid predicted (IGU-P) products are primarily available for use in real-time GPS applications. The IGU orbit precision has been remarkably improved since late 2007, but its clock products have not shown acceptably high-quality prediction performance. One reason for this fact is that satellite atomic clocks in space can be easily influenced by various factors such as temperature and environment and this leads to complicated aspects like periodic variations, which are not sufficiently described by conventional models. A more reliable prediction model is thus proposed in this paper in order to be utilized particularly in describing the periodic variation behaviour satisfactorily. The proposed prediction model for satellite clocks adds cyclic terms to overcome the periodic effects and adopts delay coordinate embedding, which offers the possibility of accessing linear or nonlinear coupling characteristics like satellite behaviour. The simulation results have shown that the proposed prediction model outperforms the IGU-P solutions at least on a daily basis.

  10. Mapping the magnetic field vector in a fountain clock

    SciTech Connect

    Gertsvolf, Marina; Marmet, Louis

    2011-12-15

    We show how the mapping of the magnetic field vector components can be achieved in a fountain clock by measuring the Larmor transition frequency in atoms that are used as a spatial probe. We control two vector components of the magnetic field and apply audio frequency magnetic pulses to localize and measure the field vector through Zeeman spectroscopy.

  11. The Vitamin C Clock Reaction.

    ERIC Educational Resources Information Center

    Wright, Stephen W.

    2002-01-01

    Describes an iodine clock reaction that produces an effect similar to the Landolt clock reaction. This reaction uses supermarket chemicals and avoids iodate, bisulfite, and mercury compounds. Ascorbic acid and tincture of iodine are the main reactants with alternate procedures provided for vitamin C tablets and orange juice. (DDR)

  12. Entanglement and spin squeezing in a network of distant optical lattice clocks

    NASA Astrophysics Data System (ADS)

    Polzik, Eugene S.; Ye, Jun

    2016-02-01

    We propose an approach for the collective enhancement of precision for remote optical lattice clocks and a way of generating the Einstein-Podolsky-Rosen (EPR) state of remote clocks. In the first scenario, a distributed spin-squeezed state (SSS) of M clocks is generated by a collective optical quantum nondemolition measurement on clocks with parallel Bloch vectors. Surprisingly, optical losses, which usually present the main limitation to SSS, can be overcome by an optimal network design which provides close to Heisenberg scaling of the time precision with the number of clocks M . We provide an optimal network solution for distant clocks as well as for clocks positioned within close proximity of each other. In the second scenario, we employ collective dissipation to drive two clocks with oppositely oriented Bloch vectors into a steady-state entanglement. The corresponding EPR state provides secret time sharing beyond the projection noise limit between the two quantum synchronized clocks protected from eavesdropping. An important application of the EPR-entangled clock pair is the remote sensing of, for example, gravitational effects and other disturbances to which clock synchronization is sensitive.

  13. The Local-Density Theory: Application to Atoms and Molecules

    NASA Astrophysics Data System (ADS)

    Guo, Yufei

    1990-01-01

    The generalized local-spin-density functional (G-LSD) theory is proposed which avoids (a) the physical restriction used in the generalized exchange local-spin -density functional (GX-LSD) theory; (b) the homogeneous electron-density approximation in the Hartree-Fock-Slater (HFS) theory and in the Gaspar-Kohn-Sham (GKS) theory; and (c) the time-consuming step to search the optimal exchange parameter for each atom or ion in the Xalpha and Xia theories. Theoretically, the G-LSD theory is more rigorous than the GX-LSD, HFS, GKS, and Xia theories. Numerically, the statistical total energies for atoms are better in the G-LSD theory than in the GKS theory. Ionization potentials and electron affinities of atoms, the stability of singly and doubly charged negative ions, and the electronegativities, and hardnesses of the fractional charged atoms with Z < 37 are calculated by the SIC-GX-LSD theory with the GWB Fermi -hole parameters and electron-correlation correction. The self-interaction correction (SIC) is introduced into the multiple-Scattering Xalpha (MS-Xalpha) method and used to calculate some molecules and molecular anions. The results show that the ionization potentials from the negative of the one-electron eigenvalues are as good as those obtained in the transition state calculation and in very good agreement with experiment.

  14. Precision Spectroscopy of Atomic Hydrogen

    NASA Astrophysics Data System (ADS)

    Beyer, A.; Parthey, Ch G.; Kolachevsky, N.; Alnis, J.; Khabarova, K.; Pohl, R.; Peters, E.; Yost, D. C.; Matveev, A.; Predehl, K.; Droste, S.; Wilken, T.; Holzwarth, R.; Hänsch, T. W.; Abgrall, M.; Rovera, D.; Salomon, Ch; Laurent, Ph; Udem, Th

    2013-12-01

    Precise determinations of transition frequencies of simple atomic systems are required for a number of fundamental applications such as tests of quantum electrodynamics (QED), the determination of fundamental constants and nuclear charge radii. The sharpest transition in atomic hydrogen occurs between the metastable 2S state and the 1S ground state. Its transition frequency has now been measured with almost 15 digits accuracy using an optical frequency comb and a cesium atomic clock as a reference [1]. A recent measurement of the 2S - 2P3/2 transition frequency in muonic hydrogen is in significant contradiction to the hydrogen data if QED calculations are assumed to be correct [2, 3]. We hope to contribute to this so-called "proton size puzzle" by providing additional experimental input from hydrogen spectroscopy.

  15. Circadian clocks: lessons from fish.

    PubMed

    Idda, M Laura; Bertolucci, Cristiano; Vallone, Daniela; Gothilf, Yoav; Sánchez-Vázquez, Francisco Javier; Foulkes, Nicholas S

    2012-01-01

    Our understanding of the molecular and cellular organization of the circadian timing system in vertebrates has increased enormously over the past decade. In large part, progress has been based on genetic studies in the mouse as well as on fundamental similarities between vertebrate and Drosophila clocks. The zebrafish was initially considered as a potentially attractive genetic model for identifying vertebrate clock genes. However, instead, fish have ultimately proven to be valuable complementary models for studying various aspects of clock biology. For example, many fish can shift from diurnal to nocturnal activity implying specific flexibility in their clock function. We have learned much about the function of light input pathways, and the ontogeny and function of the pineal organ, the fish central pacemaker. Finally, blind cavefish have also provided new insight into the evolution of the circadian clock under extreme environmental conditions. PMID:22877658

  16. Frequency ratio of Yb and Sr clocks with 5 × 10‑17 uncertainty at 150 seconds averaging time

    NASA Astrophysics Data System (ADS)

    Nemitz, Nils; Ohkubo, Takuya; Takamoto, Masao; Ushijima, Ichiro; Das, Manoj; Ohmae, Noriaki; Katori, Hidetoshi

    2016-04-01

    Transition frequencies of atoms and ions are among the most accurately accessible quantities in nature, playing important roles in pushing the frontiers of science by testing fundamental laws of physics, in addition to a wide range of applications such as satellite navigation systems. Atomic clocks based on optical transitions approach uncertainties of 10‑18 (refs 1–3), where full frequency descriptions are far beyond the reach of the SI second. Direct measurements of the frequency ratios of such super clocks, on the other hand, are not subject to this limitation. They can verify consistency and overall accuracy for an ensemble of super clocks, an essential step towards a redefinition of the second. Here we report a measurement that finds the frequency ratio of neutral ytterbium and strontium clocks to be ℛ = 1.207507039343337749(55), with a fractional uncertainty of 4.6 × 10‑17 and a measurement instability as low as 4 × 10‑16 (τ/s)‑1/2.

  17. Simulating Future GPS Clock Scenarios with Two Composite Clock Algorithms

    NASA Technical Reports Server (NTRS)

    Suess, Matthias; Matsakis, Demetrios; Greenhall, Charles A.

    2010-01-01

    Using the GPS Toolkit, the GPS constellation is simulated using 31 satellites (SV) and a ground network of 17 monitor stations (MS). At every 15-minutes measurement epoch, the monitor stations measure the time signals of all satellites above a parameterized elevation angle. Once a day, the satellite clock estimates the station and satellite clocks. The first composite clock (B) is based on the Brown algorithm, and is now used by GPS. The second one (G) is based on the Greenhall algorithm. The composite clock of G and B performance are investigated using three ground-clock models. Model C simulates the current GPS configuration, in which all stations are equipped with cesium clocks, except for masers at USNO and Alternate Master Clock (AMC) sites. Model M is an improved situation in which every station is equipped with active hydrogen masers. Finally, Models F and O are future scenarios in which the USNO and AMC stations are equipped with fountain clocks instead of masers. Model F is a rubidium fountain, while Model O is more precise but futuristic Optical Fountain. Each model is evaluated using three performance metrics. The timing-related user range error having all satellites available is the first performance index (PI1). The second performance index (PI2) relates to the stability of the broadcast GPS system time itself. The third performance index (PI3) evaluates the stability of the time scales computed by the two composite clocks. A distinction is made between the "Signal-in-Space" accuracy and that available through a GNSS receiver.

  18. Atomic temporal interval relations in branching time: calculation and application

    NASA Astrophysics Data System (ADS)

    Anger, Frank D.; Ladkin, Peter B.; Rodriguez, Rita V.

    1991-03-01

    A practical method of reasoning about intervals in a branching-time model which is dense, unbounded, future-branching, without rejoining branches is presented. The discussion is based on heuristic constraint- propagation techniques using the relation algebra of binary temporal relations among the intervals over the branching-time model. This technique has been applied with success to models of intervals over linear time by Allen and others, and is of cubic-time complexity. To extend it to branding-time models, it is necessary to calculate compositions of the relations; thus, the table of compositions for the 'atomic' relations is computed, enabling the rapid determination of the composition of arbitrary relations, expressed as disjunctions or unions of the atomic relations.

  19. The Strontium Optical Lattice Clock: Optical Spectroscopy with Sub-Hertz Accuracy

    NASA Astrophysics Data System (ADS)

    Ludlow, Andrew

    2009-05-01

    Atomic clocks find significant roles in a number of scientific and technological settings. One interesting approach to a next-generation clock based on an optical transition uses atomic strontium confined in an optical lattice. The tight atomic confinement eliminates motional effects which otherwise trouble the atomic interrogation. At the same time, the optical lattice is equally perturbs the two electronic clock states so that the confinement introduces a net zero shift of the natural transition frequency. Here I describe the design and realization of an optical frequency standard using ^87Sr confined in a 1-D optical lattice. With an ultra-stable laser light source, atomic spectral linewidths of the optical clock transition are observed below 2 Hz. High accuracy spectroscopy of the clock transition is carried out utilizing a frequency comb referenced to the NIST-F1 Cs fountain. To explore the performance of an improved, spin-polarized Sr standard, a coherent optical phase transfer link is established between JILA and NIST. This enables remote comparison of the Sr standard against optical standards at NIST. The high frequency stability of a Sr-Ca comparison (3x10-16 at 200 s) is used to make measurements of Sr transition frequency shifts at the fractional frequency level below 10-16. These systematic shifts are discussed in detail, resulting in a total uncertainty of the Sr clock frequency at 1.5x10-16, the smallest for a neutral atom system.

  20. Accuracy Evaluation of NIM5 Cesium Fountain Clock

    NASA Astrophysics Data System (ADS)

    Liu, Nian-Feng; Fang, Fang; Chen, Wei-Liang; Lin, Ping-Wei; Wang, Ping; Liu, Kun; Suo, Rui; Li, Tian-Chu

    2013-01-01

    The NIM5 fountain clock is the second fountain clock built at NIM (National Institute of Metrology, China), and has been operating stably and sub-continually since 2008. The fountain operates with a simple one-stage optical molasses to collect cold atoms, which reduces the collisional frequency shift dramatically. The fractional frequency uncertainty is estimated to be 2 × 10-15. The typical frequency instability of 2.5 × 10-14 is obtained at 10 s. Comparisons with other fountain frequency standards worldwide demonstrate agreement within the stated uncertainties.

  1. A Superfluid Clock

    NASA Technical Reports Server (NTRS)

    Penanen, Konstantin

    2004-01-01

    The performance of clocks is limited by the characteristics of the underlying oscillator. Both the quality factor of the oscillator and the signal-to-noise ratio for the resonator state measurement are important. A superfluid helium Helmholtz resonator operating at approx.100mK temperatures has the potential of maintaining frequency stability of 5x10(exp -15)/t(exp 1/2) on the time scale of a few months. The high dynamic range of lossless SQUID position displacement measurement, and low losses associated with the superfluid flow, combined with high mechanical stability of cryogenic assemblies, contribute to the projected stability. Low overall mass of the assembly allows for multiple stages of vibration isolation.

  2. Application of Density Functional Theory to Systems Containing Metal Atoms

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1997-01-01

    The accuracy of density functional theory (DFT) for problems involving metal atoms is considered. The DFT results are compared with experiment as well as results obtained using the coupled cluster approach. The comparisons include geometries, frequencies, and bond energies. The systems considered include MO2, M(OH)+(sub n), MNO+, and MCO+(sub 2). The DFT works well for frequencies and geometries, even in cases with symmetry breaking; however, some examples have been found where the symmetry breaking is quite severe and the DFT methods do not work well. The calculation of bond energies is more difficult and examples of the successes as well as failures of DFT will be given.

  3. Application of Density Functional Theory to Systems Containing Metal Atoms

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.

    2006-01-01

    The accuracy of density functional theory (DFT) for problems involving metal atoms is considered. The DFT results are compared with experiment as well as results obtained using the coupled cluster approach. The comparisons include geometries, frequencies, and bond energies. The systems considered include MO2, M(OH)+n, MNO+, and MCO+2. The DFT works well for frequencies and geometries, even in case with symmetry breaking; however, some examples have been found where the symmetry breaking is quite severe and the DFT methods do not work well. The calculation of bond energies is more difficult and examples of successes as well as failures of DFT will be given.

  4. Partial Wave Dispersion Relations: Application to Electron-Atom Scattering

    NASA Technical Reports Server (NTRS)

    Temkin, A.; Drachman, Richard J.

    1999-01-01

    In this Letter we propose the use of partial wave dispersion relations (DR's) as the way of solving the long-standing problem of correctly incorporating exchange in a valid DR for electron-atom scattering. In particular a method is given for effectively calculating the contribution of the discontinuity and/or poles of the partial wave amplitude which occur in the negative E plane. The method is successfully tested in three cases: (i) the analytically solvable exponential potential, (ii) the Hartree potential, and (iii) the S-wave exchange approximation for electron-hydrogen scattering.

  5. Direct frequency comb optical frequency standard based on two-photon transitions of thermal atoms.

    PubMed

    Zhang, S Y; Wu, J T; Zhang, Y L; Leng, J X; Yang, W P; Zhang, Z G; Zhao, J Y

    2015-01-01

    Optical clocks have been the focus of science and technology research areas due to their capability to provide highest frequency accuracy and stability to date. Their superior frequency performance promises significant advances in the fields of fundamental research as well as practical applications including satellite-based navigation and ranging. In traditional optical clocks, ultrastable optical cavities, laser cooling and particle (atoms or a single ion) trapping techniques are employed to guarantee high stability and accuracy. However, on the other hand, they make optical clocks an entire optical tableful of equipment, and cannot work continuously for a long time; as a result, they restrict optical clocks used as very convenient and compact time-keeping clocks. In this article, we proposed, and experimentally demonstrated, a novel scheme of optical frequency standard based on comb-directly-excited atomic two-photon transitions. By taking advantage of the natural properties of the comb and two-photon transitions, this frequency standard achieves a simplified structure, high robustness as well as decent frequency stability, which promise widespread applications in various scenarios. PMID:26459877

  6. Direct frequency comb optical frequency standard based on two-photon transitions of thermal atoms

    PubMed Central

    Zhang, S. Y.; Wu, J. T.; Zhang, Y. L.; Leng, J. X.; Yang, W. P.; Zhang, Z. G.; Zhao, J. Y.

    2015-01-01

    Optical clocks have been the focus of science and technology research areas due to their capability to provide highest frequency accuracy and stability to date. Their superior frequency performance promises significant advances in the fields of fundamental research as well as practical applications including satellite-based navigation and ranging. In traditional optical clocks, ultrastable optical cavities, laser cooling and particle (atoms or a single ion) trapping techniques are employed to guarantee high stability and accuracy. However, on the other hand, they make optical clocks an entire optical tableful of equipment, and cannot work continuously for a long time; as a result, they restrict optical clocks used as very convenient and compact time-keeping clocks. In this article, we proposed, and experimentally demonstrated, a novel scheme of optical frequency standard based on comb-directly-excited atomic two-photon transitions. By taking advantage of the natural properties of the comb and two-photon transitions, this frequency standard achieves a simplified structure, high robustness as well as decent frequency stability, which promise widespread applications in various scenarios. PMID:26459877

  7. Circadian clocks and breast cancer.

    PubMed

    Blakeman, Victoria; Williams, Jack L; Meng, Qing-Jun; Streuli, Charles H

    2016-01-01

    Circadian clocks respond to environmental time cues to coordinate 24-hour oscillations in almost every tissue of the body. In the breast, circadian clocks regulate the rhythmic expression of numerous genes. Disrupted expression of circadian genes can alter breast biology and may promote cancer. Here we overview circadian mechanisms, and the connection between the molecular clock and breast biology. We describe how disruption of circadian genes contributes to cancer via multiple mechanisms, and link this to increased tumour risk in women who work irregular shift patterns. Understanding the influence of circadian rhythms on breast cancer could lead to more efficacious therapies, reformed public health policy and improved patient outcome. PMID:27590298

  8. Expansion of the USDA ARS Aerial Application spray atomization models

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An effort is underway to update the USDA ARS aerial spray nozzle models using new droplet sizing instrumen-tation and measurement techniques. As part of this effort, the applicable maximum airspeed is being increased from 72 to 80 m/s to provide guidance to applicators when using new high speed air...

  9. Precision measurements with an ultracold molecular clock

    NASA Astrophysics Data System (ADS)

    Zelevinsky, Tanya

    2014-05-01

    High-precision spectroscopy has been instrumental in the progress of atomic physics. In this talk, we extend precision spectroscopy techniques to ultracold diatomic strontium molecules tightly trapped in an optical lattice, and discuss the results from the point of view of molecular and fundamental science. For weakly bound molecules near the atomic threshold corresponding to the narrow intercombination transition, we observe peculiar and unexpected physics, including multiply forbidden transitions and anomalously large linear and quadratic Zeeman shifts. The Zeeman shifts are highly sensitive to nonadiabatic mixing angles of the molecular wave functions. For the first time, we quantitatively compare the electric- and magnetic-dipole transition strengths for forbidden transitions in molecules, and discuss the dependence on the internuclear separation. In addition, we study ground state molecules, and discuss the present status of the molecular lattice clock and the physics it is able to probe. Magic-wavelength spectroscopy is successfully demonstrated for a range of narrow molecular transitions.

  10. Analytical control of wollastonite for biomedical applications by use of atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry.

    PubMed

    De Aza, P N; Guitián, F; De Aza, S; Valle, F J

    1998-04-01

    Preliminary in vitro experiments revealed that wollastonite (CaSiO3) is a potentially highly bioactive material that forms a hyroxyapatite (HA) surface layer on exposure to simulated body fluid with an ion concentration, pH and temperature virtually identical with those of human blood plasma. The formation of the HA layer is an essential requirement for an artificial material to be used as bioactive bone substitute. This finding opens up a wide field for biomedical applications of wollastonite. Biomaterials used as implants in the human body require strict control of trace elements and of the toxic species specified in American Society for Testing and Materials F-1185-88 (As, Cd, Hg and Pb) in ceramic hydroxyapatite for surgical implantation. In this work, two types of pseudowollastonite, the high temperature form of wollastonite, were analysed by using cold vapour atomic absorption spectrometry and hydride generation atomic absorption spectrometry, in order to determine the elements stated in the above-mentioned norm, and inductively coupled plasma atomic emission spectrometry to establish the SiO2/CaO ratio of the two materials and analyse for all other impurities introduced by the raw materials and by the processes of synthesis, sintering and grinding. Barium and Mg were especially prominent in raw materials, and Zr, Y, Mg, W, Co and Ni come mainly from the processing. PMID:9684401

  11. Laser cooling and trapping of atomic particles. January 1970-September 1989 (Citations from the NTIS data base). Report for Jan 70-Sep 89

    SciTech Connect

    Not Available

    1989-11-01

    This bibliography contains citations concerning theory and experiments on laser cooling and laser trapping of neutral atoms and atomic ions. Atoms and ions are cooled by laser radiation pressure to very low Kelvin temperatures and confined in electromagnetic traps with very high density. Atomic particles discussed include sodium atoms, mercury ions, beryllium ions, magnesium ions, and hydrogen. Applications include high performance spectroscopy, atomic clocks, microwave and optical frequency standards, relativistic neutral particle beam weapons, exotic fuels, cooling of electron beams, and space propulsion. (Contains 97 citations fully indexed and including a title list.)

  12. Highly charged ions as a basis of optical atomic clockwork of exceptional accuracy.

    PubMed

    Derevianko, Andrei; Dzuba, V A; Flambaum, V V

    2012-11-01

    We propose a novel class of atomic clocks based on highly charged ions. We consider highly forbidden laser-accessible transitions within the 4f(12) ground-state configurations of highly charged ions. Our evaluation of systematic effects demonstrates that these transitions may be used for building exceptionally accurate atomic clocks which may compete in accuracy with recently proposed nuclear clocks. PMID:23215265

  13. Application of the embedded atom method to Pb and Be

    NASA Technical Reports Server (NTRS)

    Karimi, M.; Yang, Z.; Tibbits, P.; Ila, D.; Dalins, I.; Vidali, G.

    1990-01-01

    We have derived the embedding energy functional and two-body potential of the embedded atom method using decreasing exponentials for both the electron density and the two body potential. The embedding function was obtained from the equation of state given by Rose et al. (1984). Because of the form of the embedding function, the equilibrium lattice constant, cohesive energy, and bulk modulus are automatically satisfied. The two parameters phi(e) and gamma of the two-body potential were determined by fitting to shear modulus and the single vacancy formation energy. Contributions of up to the third nearest neighbors were included in the evaluation of the charge density rho and the two-body potential phi. The stability and anisotropy of each structure were estimated and compared with the available experimental data.

  14. Circadian Clocks, Stress, and Immunity

    PubMed Central

    Dumbell, Rebecca; Matveeva, Olga; Oster, Henrik

    2016-01-01

    In mammals, molecular circadian clocks are present in most cells of the body, and this circadian network plays an important role in synchronizing physiological processes and behaviors to the appropriate time of day. The hypothalamic–pituitary–adrenal endocrine axis regulates the response to acute and chronic stress, acting through its final effectors – glucocorticoids – released from the adrenal cortex. Glucocorticoid secretion, characterized by its circadian rhythm, has an important role in synchronizing peripheral clocks and rhythms downstream of the master circadian pacemaker in the suprachiasmatic nucleus. Finally, glucocorticoids are powerfully anti-inflammatory, and recent work has implicated the circadian clock in various aspects and cells of the immune system, suggesting a tight interplay of stress and circadian systems in the regulation of immunity. This mini-review summarizes our current understanding of the role of the circadian clock network in both the HPA axis and the immune system, and discusses their interactions. PMID:27199894

  15. A transportable optical lattice clock

    NASA Astrophysics Data System (ADS)

    Vogt, Stefan; Häfner, Sebastian; Grotti, Jacopo; Koller, Silvio; Al-Masoudi, Ali; Sterr, Uwe; Lisdat, Christian

    2016-06-01

    We present the experimental setup and first results of PTB's transportable 87Sr clock. It consists of a physics package, several compact laser breadboards, and a transportable high finesse cavity for the clock laser. A comparison of the transportable system with our stationary optical lattice clock yields an instability of 2.2 x 10-15 √s/τ for the transportable clock. The current fractional uncertainty of 1 × 10-15 is still limited by the not yet fully evaluated light shift from the free running optical lattice laser operated near the magic wavelength. We are currently improving our transportable system to reach an uncertainty at or below the 10-17 level, which will finaly be limited by the uncertainty in blackbody radiation shift correction.

  16. The Cyanobacterial Clock and Metabolism

    PubMed Central

    Pattanayak, Gopal; Rust, Michael J.

    2014-01-01

    Cyanobacteria possess the simplest known circadian clock, which presents a unique opportunity to study how rhythms are generated and how input signals from the environment reset the clock time. The kaiABC locus forms the core of the oscillator, and the remarkable ability to reconstitute oscillations using purified KaiABC proteins has allowed researchers to study mechanism using the tools of quantitative biochemistry. Autotrophic cyanobacteria experience major shifts in metabolism following a light-dark transition, and recent work suggests that input mechanisms that couple the day-night cycle to the clock involve energy and redox metabolites acting directly on clock proteins. We offer a summary of the current state of knowledge in this system and present a perspective for future lines of investigation. PMID:24667330

  17. Application of an atomic oxygen beam facility to the investigation of shuttle glow chemistry

    NASA Technical Reports Server (NTRS)

    Arnold, G. S.; Peplinski, D. R.

    1985-01-01

    A facility for the investigation of the interactions of energetic atomic oxygen with solids is described. The facility is comprised of a four chambered, differentially pumped molecular beam apparatus which can be equipped with one of a variety of sources of atomic oxygen. The primary source is a dc arc heated supersonic nozzle source which produces a flux of atomic oxygen in excess of 10 to the 15th power sq cm/sec at the target, at a velocity of 3.5 km/sec. Results of applications of this facility to the study of the reactions of atomic oxygen with carbon and polyimide films are briefly reviewed and compared to data obtained on various flights of the space shuttle. A brief discussion of possible application of this facility to investigation of chemical reactions which might contribute to atmosphere induced vehicle glow is presented.

  18. Preliminary Evaluation of Atomization Characteristics of Improved Biodiesel for Gas Turbine Application

    NASA Astrophysics Data System (ADS)

    Kumaran, P.; Gopinathan, M.; Razali, N. M.; Kuperjans, Isabel; Hariffin, B.; Hamdan, H.

    2013-06-01

    Biodiesel is one of the clean burning alternative fuels derived from natural resources and animal fats which is promising fuel for gas turbine application. However, inferior properties of biodiesel such as high viscosity, density and surface tension results in inferior atomization and high emission, hence impedes the fuel compatible for gas turbine application and emits slightly higher emission pollutants due to inferior atomization. This research work focuses on preliminary evaluation of the atomization characteristics of derived from Malaysian waste cooking oil which is the physical properties are subsequently improved by a microwave assisted post treatment scheme. The results shows with improvement in physical properties achieved through the post treatment, biodiesel exhibits significantly better atomization characteristics in terms of spray angle, spray length, sauter mean diameter and shorter evaporation time compared to the biodiesel before improvement and fossil diesel.

  19. Common features in diverse insect clocks.

    PubMed

    Numata, Hideharu; Miyazaki, Yosuke; Ikeno, Tomoko

    2015-01-01

    This review describes common features among diverse biological clocks in insects, including circadian, circatidal, circalunar/circasemilunar, and circannual clocks. These clocks control various behaviors, physiological functions, and developmental events, enabling adaptation to periodic environmental changes. Circadian clocks also function in time-compensation for celestial navigation and in the measurement of day or night length for photoperiodism. Phase response curves for such clocks reported thus far exhibit close similarities; specifically, the circannual clock in Anthrenus verbasci shows striking similarity to circadian clocks in its phase response. It is suggested that diverse biological clocks share physiological properties in their phase responses irrespective of period length. Molecular and physiological mechanisms are best understood for the optic-lobe and mid-brain circadian clocks, although there is no direct evidence that these clocks are involved in rhythmic phenomena other than circadian rhythms in daily events. Circadian clocks have also been localized in peripheral tissues, and research on their role in various rhythmic phenomena has been started. Although clock genes have been identified as controllers of circadian rhythms in daily events, some of these genes have also been shown to be involved in photoperiodism and possibly in time-compensated celestial navigation. In contrast, there is no experimental evidence indicating that any known clock gene is involved in biological clocks other than circadian clocks. PMID:26605055

  20. Applications of Group Theory to Atoms, Molecules, and Solids

    NASA Astrophysics Data System (ADS)

    Wolfram, Thomas; Ellialtıǧlu, Şinasi

    2014-01-01

    Preface; 1. Introductory example: squarene; 2. Molecular vibrations of isotopically substituted AB2 molecules; 3. Spherical symmetry and the full rotation group; 4. Crystal field theory; 5. Electron spin and angular momentum; 6. Molecular electronic structure: the LCAO model; 7. Electronic states of diatomic molecules; 8. Transition metal complexes; 9. Space groups and crystalline solids; 10. Application of space group theory: energy bands for the perovskite structure; 11. Applications of space group theory: lattice vibrations; 12. Time reversal and magnetic groups; 13. Graphene; 14. Carbon nanotubes; Appendixes; Index.

  1. Metrology with Atom Interferometry: Inertial Sensors from Laboratory to Field Applications

    NASA Astrophysics Data System (ADS)

    Fang, B.; Dutta, I.; Gillot, P.; Savoie, D.; Lautier, J.; Cheng, B.; Garrido Alzar, C. L.; Geiger, R.; Merlet, S.; Pereira Dos Santos, F.; Landragin, A.

    2016-06-01

    Developments in atom interferometry have led to atomic inertial sensors with extremely high sensitivity. Their performances are for the moment limited by the ground vibrations, the impact of which is exacerbated by the sequential operation, resulting in aliasing and dead time. We discuss several experiments performed at LNE-SYRTE in order to reduce these problems and achieve the intrinsic limit of atomic inertial sensors. These techniques have resulted in transportable and high-performance instruments that participate in gravity measurements, and pave the way to applications in inertial navigation.

  2. Use of Atomic Oxygen for Increased Water Contact Angles of Various Polymers for Biomedical Applications

    NASA Technical Reports Server (NTRS)

    Beger, Lauren; Roberts, Lily; deGroh, Kim; Banks, Bruce

    2007-01-01

    In the low Earth orbit (LEO) space environment, spacecraft surfaces can be altered during atomic oxygen exposure through oxidation and erosion. There can be terrestrial benefits of such interactions, such as the modification of hydrophobic or hydrophilic properties of polymers due to chemical modification and texturing. Such modification of the surface may be useful for biomedical applications. For example, atomic oxygen texturing may increase the hydrophilicity of polymers, such as chlorotrifluoroethylene (Aclar), thus allowing increased adhesion and spreading of cells on textured Petri dishes. The purpose of this study was to determine the effect of atomic oxygen exposure on the hydrophilicity of nine different polymers. To determine whether hydrophilicity remains static after atomic oxygen exposure or changes with exposure, the contact angles between the polymer and a water droplet placed on the polymer s surface were measured. The polymers were exposed to atomic oxygen in a radio frequency (RF) plasma asher. Atomic oxygen plasma treatment was found to significantly alter the hydrophilicity of non-fluorinated polymers. Significant decreases in the water contact angle occurred with atomic oxygen exposure. Fluorinated polymers were found to be less sensitive to changes in hydrophilicity for equivalent atomic oxygen exposures, and two of the fluorinated polymers became more hydrophobic. The majority of change in water contact angle of the non-fluorinated polymers was found to occur with very low fluence exposures, indicating potential cell culturing benefit with short treatment time.

  3. The Application of DFT to Systems Containing Metal Atoms

    NASA Technical Reports Server (NTRS)

    Ricca, Alessandra; Bauschlicher, Charles W., Jr.; Arnold, James O. (Technical Monitor)

    1996-01-01

    The application of density functional theory (DFT) to a series of metal containing systems will be described. The focus will be on the calculation of accurate bond energies, especially metal-ligand successive bond energies. The DFT results will be compared with experiment and other levels of theory. If time permits, metal clusters will also be discussed.

  4. Quantum Metrology with Lattice-Confined Ultracold SR Atoms

    NASA Astrophysics Data System (ADS)

    Ludlow, A. D.; Campbell, G. K.; Blatt, S.; Boyd, M. M.; Martin, M. J.; Nicholson, T. L.; Swallows, M.; Thomsen, J. W.; Fortier, T.; Oates, C. W.; Diddams, S. A.; Lemke, N. D.; Barber, Z.; Porsev, S. G.; Ye, Jun

    2009-04-01

    Quantum state engineering of ultracold matter and precise control of optical fields have together allowed accurate measurement of light-matter interactions for applications in precision tests of fundamental physics. State-of-the-art lasers maintain optical phase coherence over one second. Optical frequency combs distribute this optical phase coherence across the entire visible and infrared parts of the electromagnetic spectrum, leading to the direct visualization and measurement of light ripples. At the same time, ultracold atoms confined in an optical lattice with zero differential ac Stark shift between two clock states allow us to minimize quantum decoherence while strengthening the clock signal. For 87Sr, we achieve a resonance quality factor > 2.4 × 1014 on the 1S0 - 3P0 doubly forbidden clock transition at 698 nm [1]. The uncertainty of this new clock has reached 1 × 10-16 and its instability approaches 1 × 10-15 at 1 s [2]. These developments represent a remarkable convergence of ultracold atoms, laser stabilization, and ultrafast science. Further improvements are still tantalizing, with quantum measurement and precision metrology combining forces to explore the next frontier.

  5. Test of an orbiting hydrogen maser clock system using laser time transfer

    NASA Astrophysics Data System (ADS)

    Vessot, Robert F. C.; Mattison, Edward M.; Nystrom, G. U.; Decher, Rudolph

    1992-07-01

    We describe a joint Smithsonian Astrophysical Laboratory/National Aeronautics and Space Administration (SAO/NASA) program for flight testing a atomic hydrogen maser clock system designed for long-term operation in space. The clock system will be carried by a shuttle-launched EURECA spacecraft. Comparisons with earth clocks to measure the clock's long-term frequency stability (tau = 10(exp 4) seconds) will be made using laser time transfer from existing NASA laser tracking stations. We describe the design of the maser clock and its control systems, and the laser timing technique. We describe the precision of station time synchronization and the limitations in the comparison between the earth and space time scales owing to gravitational and relativistic effects. We will explore the implications of determining the spacecraft's location by an on-board Global Position System (GPS) receiver, and of using microwave techniques for time and frequency transfer.

  6. Test of an orbiting hydrogen maser clock system using laser time transfer

    NASA Technical Reports Server (NTRS)

    Vessot, Robert F. C.; Mattison, Edward M.; Nystrom, G. U.; Decher, Rudolph

    1992-01-01

    We describe a joint Smithsonian Astrophysical Laboratory/National Aeronautics and Space Administration (SAO/NASA) program for flight testing a atomic hydrogen maser clock system designed for long-term operation in space. The clock system will be carried by a shuttle-launched EURECA spacecraft. Comparisons with earth clocks to measure the clock's long-term frequency stability (tau = 10(exp 4) seconds) will be made using laser time transfer from existing NASA laser tracking stations. We describe the design of the maser clock and its control systems, and the laser timing technique. We describe the precision of station time synchronization and the limitations in the comparison between the earth and space time scales owing to gravitational and relativistic effects. We will explore the implications of determining the spacecraft's location by an on-board Global Position System (GPS) receiver, and of using microwave techniques for time and frequency transfer.

  7. Cold atomic beam ion source for focused ion beam applications

    SciTech Connect

    Knuffman, B.; Steele, A. V.; McClelland, J. J.

    2013-07-28

    We report measurements and modeling of an ion source that is based on ionization of a laser-cooled atomic beam. We show a high brightness and a low energy spread, suitable for use in next-generation, high-resolution focused ion beam systems. Our measurements of total ion current as a function of ionization conditions support an analytical model that also predicts the cross-sectional current density and spatial distribution of ions created in the source. The model predicts a peak brightness of 2 × 10{sup 7} A m{sup −2} sr{sup −1} eV{sup −1} and an energy spread less than 0.34 eV. The model is also combined with Monte-Carlo simulations of the inter-ion Coulomb forces to show that the source can be operated at several picoamperes with a brightness above 1 × 10{sup 7} A m{sup −2} sr{sup −1} eV{sup −1}. We estimate that when combined with a conventional ion focusing column, an ion source with these properties could focus a 1 pA beam into a spot smaller than 1 nm. A total current greater than 5 nA was measured in a lower-brightness configuration of the ion source, demonstrating the possibility of a high current mode of operation.

  8. ORTHO- ELIMINATION OF TRACKING SYSTEM CLOCK ERRORS

    NASA Technical Reports Server (NTRS)

    Wu, J. T.

    1994-01-01

    ORTHO is part of the Global Positioning System (GPS) being developed by the U.S. Air Force, a navigational system that will use 18 NAVSTAR satellites to broadcast navigation messages and achieve worldwide coverage. The normal positioning technique uses one receiver which receives signals from at least four GPS satellites. For higher accuracy work it is often necessary to use a differential technique in which more than one receiver is used. The geodetic measurement has all receivers on the ground and allows the determination of the relative locations of the ground sites. The main application of the ORTHO program is in the elimination of clock errors in a GPS based tracking system. The measured distance (pseudo-range) from a GPS receiver contains errors due to differences in the receiver and satellite clocks. The conventional way of eliminating clock errors is to difference pseudo-ranges between different GPS satellites and receivers. The Householder transformation used in this program performs a function similar to the conventional single differencing or double differencing. This method avoids the problem of redundancy and correlation encountered in a differencing scheme. It is able to keep all information contained in the measurements within the scope of a least square estimation. For multiple transmitter and receiver GPS tracking network, this method is in general more accurate than the differencing technique. This program assumes that the non-clock measurement partial derivatives for the particular application are computed earlier by another program. With the partial derivatives and information to identify the transmitters and receivers as the input, the program performs the Householder transformation on the partial derivatives. The transformed partials are output by the program and may be used as an input to the filter program in the subsequent estimation process. Clock partial derivatives are generated internally and are not part of the input to the program

  9. Integrating Carbon Nanotubes For Atomic Force Microscopy Imaging Applications

    NASA Technical Reports Server (NTRS)

    Ye, Qi; Cassell, Alan M.; Liu, Hongbing; Han, Jie; Meyyappan, Meyya

    2004-01-01

    Carbon nanotube (CNT) related nanostructures possess remarkable electrical, mechanical, and thermal properties. To produce these nanostructures for real world applications, a large-scale controlled growth of carbon nanotubes is crucial for the integration and fabrication of nanodevices and nanosensors. We have taken the approach of integrating nanopatterning and nanomaterials synthesis with traditional silicon micro fabrication techniques. This integration requires a catalyst or nanomaterial protection scheme. In this paper, we report our recent work on fabricating wafer-scale carbon nanotube AFM cantilever probe tips. We will address the design and fabrication considerations in detail, and present the preliminary scanning probe test results. This work may serve as an example of rational design, fabrication, and integration of nanomaterials for advanced nanodevice and nanosensor applications.

  10. Pitfalls of Insulin Pump Clocks

    PubMed Central

    Reed, Amy J.

    2014-01-01

    The objective was to raise awareness about the importance of ensuring that insulin pumps internal clocks are set up correctly at all times. This is a very important safety issue because all commercially available insulin pumps are not GPS-enabled (though this is controversial), nor equipped with automatically adjusting internal clocks. Special attention is paid to how basal and bolus dose errors can be introduced by daylight savings time changes, travel across time zones, and am-pm clock errors. Correct setting of insulin pump internal clock is crucial for appropriate insulin delivery. A comprehensive literature review is provided, as are illustrative cases. Incorrect setting can potentially result in incorrect insulin delivery, with potential harmful consequences, if too much or too little insulin is delivered. Daylight saving time changes may not significantly affect basal insulin delivery, given the triviality of the time difference. However, bolus insulin doses can be dramatically affected. Such problems may occur when pump wearers have large variations in their insulin to carb ratio, especially if they forget to change their pump clock in the spring. More worrisome than daylight saving time change is the am-pm clock setting. If this setting is set up incorrectly, both basal rates and bolus doses will be affected. Appropriate insulin delivery through insulin pumps requires correct correlation between dose settings and internal clock time settings. Because insulin pumps are not GPS-enabled or automatically time-adjusting, extra caution should be practiced by patients to ensure correct time settings at all times. Clinicians and diabetes educators should verify the date/time of insulin pumps during patients’ visits, and should remind their patients to always verify these settings. PMID:25355713

  11. Rydberg Excitation of Single Atoms for Applications in Quantum Information and Metrology

    SciTech Connect

    Hankin, Aaron Michael

    2014-08-01

    With the advent of laser cooling and trapping, neutral atoms have become a foundational source of accuracy for applications in metrology and are showing great potential for their use as qubits in quantum information. In metrology, neutral atoms provide the most accurate references for the measurement of time and acceleration. The unsurpassed stability provided by these systems make neutral atoms an attractive avenue to explore applications in quantum information and computing. However, to fully investigate the eld of quantum information, we require a method to generate entangling interactions between neutral-atom qubits. Recent progress in the use of highly-excited Rydberg states for strong dipolar interactions has shown great promise for controlled entanglement using the Rydberg blockade phenomenon. I report the use of singly-trapped 133Cs atoms as qubits for applications in metrology and quantum information. Each atom provides a physical basis for a single qubit by encoding the required information into the ground-state hyper ne structure of 133Cs. Through the manipulation of these qubits with microwave and optical frequency sources, we demonstrate the capacity for arbitrary single-qubit control by driving qubit rotations in three orthogonal directions on the Bloch sphere. With this control, we develop an atom interferometer that far surpasses the force sensitivity of other approaches by applying the well-established technique of lightpulsed atom-matterwave interferometry to single atoms. Following this, we focus on two-qubit interactions using highly-excited Rydberg states. Through the development of a unique single-photon approach to Rydberg excitation using an ultraviolet laser at 319 nm, we observe the Rydberg blockade interaction between atoms separated by 6.6(3) m. Motivated by the observation of Rydberg blockade, we study the application of Rydberg-dressed states for a quantum controlled-phase gate. Using a realistic simulation of the

  12. Rydberg Excitation of Single Atoms for Applications in Quantum Information and Metrology

    NASA Astrophysics Data System (ADS)

    Hankin, Aaron Michael

    With the advent of laser cooling and trapping, neutral atoms have become a foundational source of accuracy for applications in metrology and are showing great potential for their use as qubits in quantum information. In metrology, neutral atoms provide the most accurate references for the measurement of time and acceleration. The unsurpassed stability provided by these systems make neutral atoms an attractive avenue to explore applications in quantum information and computing. However, to fully investigate the field of quantum information, we require a method to generate entangling interactions between neutral-atom qubits. Recent progress in the use of highly-excited Rydberg states for strong dipolar interactions has shown great promise for controlled entanglement using the Rydberg blockade phenomenon. I report the use of singly-trapped cesium-133 atoms as qubits for applications in metrology and quantum information. Each atom provides a physical basis for a single qubit by encoding the required information into the ground-state hyperfine structure of cesium-133. Through the manipulation of these qubits with microwave and optical frequency sources, we demonstrate the capacity for arbitrary single-qubit control by driving qubit rotations in three orthogonal directions on the Bloch sphere. With this control, we develop an atom interferometer that far surpasses the force sensitivity of other approaches by applying the well-established technique of light-pulsed atom-matterwave interferometry to single atoms. Following this, we focus on two-qubit interactions using highly-excited Rydberg states. Through the development of a unique single-photon approach to Rydberg excitation using an ultraviolet laser at 319 nm, we observe the Rydberg blockade interaction between atoms separated by 6.6(3) μm. Motivated by the observation of Rydberg blockade, we study the application of Rydberg-dressed states for a quantum controlled-phase gate. Using a realistic simulation of the

  13. High accuracy correction of blackbody radiation shift in an optical lattice clock.

    PubMed

    Middelmann, Thomas; Falke, Stephan; Lisdat, Christian; Sterr, Uwe

    2012-12-28

    We have determined the frequency shift that blackbody radiation is inducing on the 5s2 (1)S0-5s5p (3)P0 clock transition in strontium. Previously its uncertainty limited the uncertainty of strontium lattice clocks to 1×10(-16). Now the uncertainty associated with the blackbody radiation shift correction translates to a 5×10(-18) relative frequency uncertainty at room temperature. Our evaluation is based on a measurement of the differential dc polarizability of the two clock states and on a modeling of the dynamic contribution using this value and experimental data for other atomic properties. PMID:23368558

  14. High Accuracy Correction of Blackbody Radiation Shift in an Optical Lattice Clock

    NASA Astrophysics Data System (ADS)

    Middelmann, Thomas; Falke, Stephan; Lisdat, Christian; Sterr, Uwe

    2012-12-01

    We have determined the frequency shift that blackbody radiation is inducing on the 5s2 S01-5s5p P03 clock transition in strontium. Previously its uncertainty limited the uncertainty of strontium lattice clocks to 1×10-16. Now the uncertainty associated with the blackbody radiation shift correction translates to a 5×10-18 relative frequency uncertainty at room temperature. Our evaluation is based on a measurement of the differential dc polarizability of the two clock states and on a modeling of the dynamic contribution using this value and experimental data for other atomic properties.

  15. Engineering Stark Potentials for Precision Measurements: Optical Lattice Clock and Electrodynamic Surface Trap

    SciTech Connect

    Katori, Hidetoshi; Takamoto, Masao; Hachisu, Hidekazu; Fujiki, Jun; Higashi, Ryoichi; Yasuda, Masami; Kishimoto, Tetsuo

    2005-05-05

    Employing the engineered electric fields, we demonstrate novel platforms for precision measurements with neutral atoms. (1) Applying the light shift cancellation technique, atoms trapped in an optical lattice reveal 50-Hz-narrow optical spectrum, yielding nearly an order of magnitude improvement over existing neutral-atom-based clocks. (2) Surface Stark trap has been developed to manipulate scalar atoms that are intrinsically robust to decoherence.

  16. A clock directly linking time to a particle's mass.

    PubMed

    Lan, Shau-Yu; Kuan, Pei-Chen; Estey, Brian; English, Damon; Brown, Justin M; Hohensee, Michael A; Müller, Holger

    2013-02-01

    Historically, time measurements have been based on oscillation frequencies in systems of particles, from the motion of celestial bodies to atomic transitions. Relativity and quantum mechanics show that even a single particle of mass m determines a Compton frequency ω(0) = mc(2)/[formula: see text] where c is the speed of light and [formula: see text] is Planck's constant h divided by 2π. A clock referenced to ω(0) would enable high-precision mass measurements and a fundamental definition of the second. We demonstrate such a clock using an optical frequency comb to self-reference a Ramsey-Bordé atom interferometer and synchronize an oscillator at a subharmonic of ω(0.) This directly demonstrates the connection between time and mass. It allows measurement of microscopic masses with 4 × 10(-9) accuracy in the proposed revision to SI units. Together with the Avogadro project, it yields calibrated kilograms. PMID:23306441

  17. Circadian clocks and cell division

    PubMed Central

    2010-01-01

    Evolution has selected a system of two intertwined cell cycles: the cell division cycle (CDC) and the daily (circadian) biological clock. The circadian clock keeps track of solar time and programs biological processes to occur at environmentally appropriate times. One of these processes is the CDC, which is often gated by the circadian clock. The intermeshing of these two cell cycles is probably responsible for the observation that disruption of the circadian system enhances susceptibility to some kinds of cancer. The core mechanism underlying the circadian clockwork has been thought to be a transcription and translation feedback loop (TTFL), but recent evidence from studies with cyanobacteria, synthetic oscillators and immortalized cell lines suggests that the core circadian pacemaking mechanism that gates cell division in mammalian cells could be a post-translational oscillator (PTO). PMID:20890114

  18. Synchronous clock stopper for microprocessor

    NASA Technical Reports Server (NTRS)

    Kitchin, David A. (Inventor)

    1985-01-01

    A synchronous clock stopper circuit for inhibiting clock pulses to a microprocessor in response to a stop request signal, and for reinstating the clock pulses in response to a start request signal thereby to conserve power consumption of the microprocessor when used in an environment of limited power. The stopping and starting of the microprocessor is synchronized, by a phase tracker, with the occurrences of a predetermined phase in the instruction cycle of the microprocessor in which the I/O data and address lines of the microprocessor are of high impedance so that a shared memory connected to the I/O lines may be accessed by other peripheral devices. The starting and stopping occur when the microprocessor initiates and completes, respectively, an instruction, as well as before and after transferring data with a memory. Also, the phase tracker transmits phase information signals over a bus to other peripheral devices which signals identify the current operational phase of the microprocessor.

  19. Clocks, Metabolism, and the Epigenome

    PubMed Central

    Feng, Dan; Lazar, Mitchell A.

    2012-01-01

    Many behaviors and physiological activities in living organisms display circadian rhythms, allowing them to anticipate and prepare for the diurnal changes in the living environment. In this way, metabolic processes are aligned with the periodic environmental changes and behavioral cycles, such as the sleep/wake and fasting/feeding cycles. Disturbances of this alignment significantly increase the risk of metabolic diseases. Meanwhile, the circadian clock receives signals from the environment and feedback from metabolic pathways, and adjusts its activity and function. Growing evidence connects the circadian clock with epigenomic regulators. Here we review the recent advances in understanding the crosstalk between the circadian clock and energy metabolism through epigenomic programming and transcriptional regulation. PMID:22841001

  20. Sr+ single-ion clock

    NASA Astrophysics Data System (ADS)

    Dubé, P.; Madej, A. A.; Jian, B.

    2016-06-01

    The evaluated uncertainty of the 88Sr+ ion optical clock has decreased by several orders of magnitude during the last 15 years, currently reaching a level of 1.2 x 10-17. In this paper, we review the methods developed to control very effectively the largest frequency shifts that once were the main sources of uncertainty for the 88Sr+ single-ion clock. These shifts are the micromotion shifts, the electric quadrupole shift and the blackbody radiation shift. With further improvements to the evaluation of the systematic shifts, especially the blackbody radiation shift, it is expected that the total uncertainty of the single-ion clock transition frequency will reach the low 10-18 level in the near future.

  1. Titan's methane clock

    NASA Astrophysics Data System (ADS)

    Nixon, C. A.; Jennings, D. E.; Romani, P. N.; Teanby, N. A.; Irwin, P. G. J.; Flasar, F. M.

    2010-04-01

    Measurements of the 12C/13C and D/H isotopic ratios in Titan's methane show intriguing differences from the values recorded in the giant planets. This implies that either (1) the atmosphere was differently endowed with material at the time of formation, or (2) evolutionary processes are at work in the moon's atmosphere - or some combination of the two. The Huygens Gas Chromatograph Mass Spectrometer Instrument (GCMS) found 12CH4/13CH4 = 82 +/- 1 (Niemann et al. 2005), some 7% lower than the giant planets' value of 88 +/- 7 (Sada et al. 1996), which closely matches the terrestrial inorganic standard of 89. The Cassini Composite Infrared Spectrometer (CIRS) has previously reported 12CH4/13CH4 of 77 +/-3 based on nadir sounding, which we now revise upwards to 80 +/- 4 based on more accurate limb sounding. The CIRS and GCMS results are therefore in agreement about an overall enrichment in 13CH4 of ~10%. The value of D/H in Titan's CH4 has long been controversial: historical measurements have ranged from about 8-15 x 10-5 (e.g. Coustenis et al. 1989, Coustenis et al. 2003). A recent measurement based on CIRS limb data by Bezard et al. (2007) puts the D/H in CH4 at (13 +/- 1) x 10-5, very much greater than in Jupiter and Saturn, ~2 x 10-5 (Mahaffy et al. 1998, Fletcher et al. 2009). To add complexity, the 12C/13C and D/H vary among molecules in Titan atmosphere, typically showing enhancement in D but depletion in 13C in the daughter species (H2, C2H2, C2H6), relative to the photochemical progenitor, methane. Jennings et al. (2009) have sought to interpret the variance in carbon isotopes as a Kinetic Isotope Effect (KIE), whilst an explanation for the D/H in all molecules remains elusive (Cordier et al. 2008). In this presentation we argue that evolution of isotopic ratios in Titan's methane over time forms a ticking 'clock', somewhat analogous to isotopic ratios in geochronology. Under plausible assumptions about the initial values and subsequent replenishment, various

  2. The physics of spin polarized atomic vapors

    NASA Astrophysics Data System (ADS)

    Happer, William

    1988-05-01

    Research efforts are focussed on the study of spin polarized atoms, nuclei and electrons during the period covered by this report. Although this work is 6.1 basic research, it has applications to a number of important Air Force problems. For example, the atomic clocks used on the GPS satellite system operate with optically pumped rubidium absorption cells, very similar to the ones being investigated here. A number of the scientists and engineers working on atomic clocks used by Air Force satellite systems were trained with the support of this grant. We have participated in recent Air Force advisory panels to review concepts for high-energy-density fuels based on spin polarized atoms and molecules. The insights gained from research sponsored by this grant have been very useful in evaluating these ideas. Recent work has focussed on two main areas, the investigation of quadrupolar interactions between spin polarized noble gas nuclei and surfaces and the quantitative investigation of how magnetic field inhomogeneities cause spin relaxation.

  3. Phase modulation for reduced vibration sensitivity in laser-cooled clocks in space

    NASA Technical Reports Server (NTRS)

    Klipstein, W.; Dick, G.; Jefferts, S.; Walls, F.

    2001-01-01

    The standard interrogation technique in atomic beam clocks is square-wave frequency modulation (SWFM), which suffers a first order sensitivity to vibrations as changes in the transit time of the atoms translates to perceived frequency errors. Square-wave phase modulation (SWPM) interrogation eliminates sensitivity to this noise.

  4. Polarizabilities of the beryllium clock transition

    SciTech Connect

    Mitroy, J.

    2010-11-15

    The polarizabilities of the three lowest states of the beryllium atom are determined from a large basis configuration interaction calculation. The polarizabilities of the 2s{sup 2} {sup 1}S{sup e} ground state (37.73a{sub 0}{sup 3}) and the 2s2p {sup 3}P{sub 0}{sup o} metastable state (39.04a{sub 0}{sup 3}) are found to be very similar in size and magnitude. This leads to an anomalously small blackbody radiation shift at 300 K of -0.018(4) Hz for the 2s{sup 2} {sup 1}S{sup e}-2s2p {sup 3}P{sub 0}{sup o} clock transition. Magic wavelengths for simultaneous trapping of the ground and metastable states are also computed.

  5. Improved Frequency Measurement of a One-Dimensional Optical Lattice Clock with a Spin-Polarized Fermionic 87Sr Isotope

    NASA Astrophysics Data System (ADS)

    Takamoto, Masao; Hong, Feng-Lei; Higashi, Ryoichi; Fujii, Yasuhisa; Imae, Michito; Katori, Hidetoshi

    2006-10-01

    We demonstrate a one-dimensional optical lattice clock with a spin-polarized fermionic isotope designed to realize a collision-shift-free atomic clock with neutral atom ensembles. To reduce systematic uncertainties, we developed both Zeeman shift and vector light-shift cancellation techniques. By introducing both an H-maser and a global positioning system (GPS) carrier phase link, the absolute frequency of the 1S0(F=9/2)-{}3P0(F=9/2) clock transition of the 87Sr optical lattice clock is determined as 429,228,004,229,875(4) Hz, where the uncertainty is mainly limited by that of the frequency link. The result indicates that the Sr lattice clock will play an important role in the scope of the redefinition of the “second” by optical frequency standards.

  6. Optimized multiparty quantum clock synchronization

    SciTech Connect

    Ben-Av, Radel; Exman, Iaakov

    2011-07-15

    A multiparty protocol for distributed quantum clock synchronization has been claimed to provide universal limits on the clock accuracy, viz., that accuracy monotonically decreases with the number n of party members. But this is only true for synchronization when one limits oneself to W states. This work shows that the usage of Z (Symmetric Dicke) states, a generalization of W states, results in improved accuracy, having a maximum when Left-Floor n/2 Right-Floor of its members have their qubits with a |1> eigenstate.

  7. Acting with the Clock: Clocking Practices in Early Childhood

    ERIC Educational Resources Information Center

    Pacini-Ketchabaw, Veronica

    2012-01-01

    In this article, the author addresses intra-actions that take place among humans and non-human others--the physical world, the materials--in early childhood education's everyday practices. Her object of study is the clock. Specifically, she provides an example of what it might mean to account for the intra-activity of the material-discursive…

  8. Naming Analog Clocks Conceptually Facilitates Naming Digital Clocks

    ERIC Educational Resources Information Center

    Meeuwissen, Marjolein; Roelofs, Ardi; Levelt, Willem J. M.

    2004-01-01

    This study investigates how speakers of Dutch compute and produce relative time expressions. Naming digital clocks (e.g., 2:45, say ''quarter to three'') requires conceptual operations on the minute and hour information for the correct relative time expression. The interplay of these conceptual operations was investigated using a repetition…

  9. Single-transistor-clocked flip-flop

    DOEpatents

    Zhao, Peiyi; Darwish, Tarek; Bayoumi, Magdy

    2005-08-30

    The invention provides a low power, high performance flip-flop. The flip-flop uses only one clocked transistor. The single clocked transistor is shared by the first and second branches of the device. A pulse generator produces a clock pulse to trigger the flip-flop. In one preferred embodiment the device can be made as a static explicit pulsed flip-flop which employs only two clocked transistors.

  10. FOREWORD: Fifty years of atomic time-keeping: 1955 to 2005

    NASA Astrophysics Data System (ADS)

    Quinn, Terry

    2005-06-01

    the commercial development of atomic clocks of various types and on some of their applications. At the beginning there is a deliberate emphasis on the history of the introduction of atomic time, including the technical problems to be resolved and the personalities involved. You will see that it includes one article based on notes left by Louis Essen himself, for which we are most grateful to his son, Mr Ray Essen, for permission to use them and to Dale Henderson of the NPL, who arranged them for publication here. I hope that this issue will stand as a reference for years to come and I am most grateful to all those who have contributed. I also wish to thank most particularly Norman Ramsey, whose name is indelibly associated with atomic clocks, for having contributed the first article to this special issue.

  11. Developments and performances of cold atom inertial sensors for space applications

    NASA Astrophysics Data System (ADS)

    Landragin, Arnaud

    The techniques of laser cooling combined with atom interferometry make possible the real-ization of high performance inertial sensors like gyroscopes or accelerometers. Their excellent sensitivity and accuracy make these instruments very interesting tools for testing gravity and relativity[1]. Developments in atom interferometry already lead to performances at the level of the state of the art sensors on ground. Moreover, current developments aims to push ground performances[2] and to make these technologies compatible with the space environment[3]. The detailed characterization of these sensors[4] enables an extrapolations of performances in space[5], where they would benefit from much longer interrogation time and higher sensitivity. [1] G. Varoquaux, et al. "How to estimate the differential acceleration in a two-species atom interferometer to test the equivalence principle", New Journal of Physics 11, 113010 (2009). [2] T. Lév`que, et al., "Enhancing the area of a Raman atom interferometer using a versatile double-diffraction technique", Physical Review Letters 103, 080405 (2009). [3] G. Stern, et al., "Light-pulse atom interferometry in microgravity", Eur. Phys. J. D 53, 353-357 (2009). [4] A. Gauguet, et al., "Characterization and limits of a cold atom Sagnac interferometer", Physical Review A 80, 063604, (2009). [5] A. Landragin, and F. Pereira Dos Santos, "Accelerometer using atomic waves for space applications", in Atom Optics and Space Physics, Proceedings of the Enrico Fermi International School of Physics "Enrico Fermi," Course CLXVIII, Varenna, 2007, edited by E. Arimondo, W. Ertmer, E. M. Rasel, and W. P. Schleich (IOS press) p337-350, arXiv:0808.3837v1 (2009).

  12. Rapid evaluation of time scale using an optical clock

    NASA Astrophysics Data System (ADS)

    Ido, T.; Hachisu, H.; Nakagawa, F.; Hanado, Y.

    2016-06-01

    Feasibility of steering a time scale using an optical clock is investigated. Since the high stability of optical frequency standards enables rapid evaluation of the scale interval, the requirement for the continuous operation is mitigated. Numerical simulations with the input of real calibration data by a 87Sr lattice clock indicated that the calibrations once in two weeks maintain the time scale within 5 ns level using a currently available hydrogen maser at NICT. “Optical” steering of a time scale by the intermittent calibrations frees an optical frequency standard from being dedicated to the steering, enabling other applications using the same apparatus.

  13. 47 CFR 80.935 - Station clock.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Station clock. 80.935 Section 80.935... MARITIME SERVICES Compulsory Radiotelephone Installations for Small Passenger Boats § 80.935 Station clock. Each station subject to this subpart must have a working clock or timepiece readily available to...

  14. Time and clock synchronization with AFCK for CBM

    NASA Astrophysics Data System (ADS)

    Gumiński, M.; Zabołotny, W.; Kasprowicz, G.; Poźniak, K.; Romaniuk, R.

    2015-09-01

    The AMC FMC Carrier Kintex (AFCK) board is a prototype of Data Processing Board (DPB) for CBM experiment. AFCK is open hardware and was designed to be a versatile solution, applicable in multiple systems. In CBM experiment AFCK will serve as a data hub and communication interconnection. One of DPB's functions is synchronization of Front End Electronics (FEE). To provide this functionality, it is necessary to receive the reference clock and timing signals from the Timing and Flow Control system. The received clock after the jitter cleaning will be used as a reference clock for GBT-FPGA based 4.8 Gbps links used for communication with front end electronics. This article will briefly describe AFCK board function in CBM experiment. Afterwards it will focus on jitter cleaning technique based on White Rabbit solution that can be used on AFCK board.

  15. Quantum theory of an electron waiting time clock

    NASA Astrophysics Data System (ADS)

    Dasenbrook, David; Flindt, Christian

    2016-06-01

    The electron waiting time is the time that passes between two subsequent charge transfers in an electronic conductor. Recently, theories of electron waiting times have been devised for quantum transport in Coulomb-blockade structures and for mesoscopic conductors; however, so far a proper description of a detector has been missing. Here we develop a quantum theory of a waiting time clock capable of measuring the distribution of waiting times between electrons above the Fermi sea in a mesoscopic conductor. The detector consists of a mesoscopic capacitor coupled to a quantum two-level system whose coherent precession we monitor. Under ideal operating conditions our waiting time clock recovers the results of earlier theories without a detector. We investigate possible deviations due to an imperfect waiting time clock. As specific applications we consider a quantum point contact with a constant voltage and Lorentzian voltage pulses applied to an electrode.

  16. The NIST 27 Al+ quantum-logic clock

    NASA Astrophysics Data System (ADS)

    Leibrandt, David; Brewer, Samuel; Chen, Jwo-Sy; Hume, David; Hankin, Aaron; Huang, Yao; Chou, Chin-Wen; Rosenband, Till; Wineland, David

    2016-05-01

    Optical atomic clocks based on quantum-logic spectroscopy of the 1 S0 <--> 3 P0 transition in 27 Al+ have reached a systematic fractional frequency uncertainty of 8 . 0 ×10-18 , enabling table-top tests of fundamental physics as well as measurements of gravitational potential differences. Currently, the largest limitations to the accuracy are second order time dilation shifts due to the driven motion (i.e., micromotion) and thermal motion of the trapped ions. In order to suppress these shifts, we have designed and built new ion traps based on gold-plated, laser-machined diamond wafers with differential RF drive, and we have operated one of our clocks with the ions laser cooled to near the six mode motional ground state. We present a characterization of the time dilation shifts in the new traps with uncertainties near 1 ×10-18 . Furthermore, we describe a new protocol for clock comparison measurements based on synchronous probing of the two clocks using phase-locked local oscillators, which allows for probe times longer than the laser coherence time and avoids the Dick effect. This work is supported by ARO, DARPA, and ONR.

  17. The in-orbit performances of GIOVE clocks.

    PubMed

    Waller, Pierre; Gonzalez, Francisco; Binda, Stefano; Sesia, Ilaria; Hidalgo, Irene; Tobias, Guillermo; Tavella, Patrizia

    2010-03-01

    The Galileo In-Orbit Validation Element (GIOVE) is an experiment led by the European Space Agency (ESA) aimed at supporting the on-going implementation of Galileo, the European global navigation satellite system (GNSS). Among the objectives of the GIOVE Mission are the validation and characterization of the on-board clock technologies. The current baseline technologies for on-board clocks are the rubidium atomic frequency standard (RAFS) and the passive hydrogen maser (PHM). Both technologies have been validated and qualified on ground and are now being further validated in a representative in-orbit environment aboard 2 spacecrafts, GIOVE-A and GIOVE-B. This paper presents the results obtained in the frame of the GIOVE experimentation. The behavior and performances of the clock technologies on board both spacecrafts has been investigated and analyzed in terms of operation, frequency stability, and clock prediction error after more than 3 years of operation for GIOVE-A and almost one year for GIOVE-B. In addition, relativistic frequency shifts of GIOVE spacecrafts have been investigated. PMID:20211795

  18. Clock Drawing in Developmental Dyslexia.

    ERIC Educational Resources Information Center

    Eden, Guinevere F.; Wood, Frank B.; Stein, John F.

    2003-01-01

    A study involving 93 children (ages 10-12), 295 with poor reading skills, found many children with dyslexia and some garden-variety poor readers showed significant left neglect on the Clock Drawing Test. In poor readers with dyslexia, spatial construction deficits were observed like those of parents with acquired right-hemisphere lesions.…

  19. Light scattering from dense cold atomic media

    NASA Astrophysics Data System (ADS)

    Zhu, Bihui; Cooper, John; Ye, Jun; Rey, Ana Maria

    2016-08-01

    We theoretically study the propagation of light through a cold atomic medium, where the effects of motion, laser intensity, atomic density, and polarization can all modify the properties of the scattered light. We present two different microscopic models: the "coherent dipole model" and the "random-walk model", both suitable for modeling recent experimental work done in large atomic arrays in the low-light-intensity regime. We use them to compute relevant observables such as the linewidth, peak intensity, and line center of the emitted light. We further develop generalized models that explicitly take into account atomic motion. Those are relevant for hotter atoms and beyond the low-intensity regime. We show that atomic motion can lead to drastic dephasing and to a reduction of collective effects, together with a distortion of the line shape. Our results are applicable to model a full gamut of quantum systems that rely on atom-light interactions, including atomic clocks, quantum simulators, and nanophotonic systems.

  20. The Chemical and Educational Appeal of the Orange Juice Clock

    NASA Astrophysics Data System (ADS)

    Kelter, Paul B.; Carr, James D.; Johnson, Tanya; Mauricio Castro-Acuña, Carlos

    1996-12-01

    characterized by seeing educational possibilities in so many things, created a modified version of the clock, with the atomic numbers of the elements representing the hours in the day (see Fig. 2) in his internationally popular workshops. Due largely to Talesnick's efforts, the orange juice clock is a standard demonstration in many chemistry programs and presentations. Figure 2.Irwin Talesnick represents the hours of the day by the corresponding elements in his clock. The Procedure This can be done as a demonstration or as an activity, although at about 10 per clock, expense does become an issue. There are no unusual safety precautions with this demonstration. We know of no accidents that have occurred with the orange juice clock. The demonstration requires: a single AA-cell battery-operated wall clock with a sweep-second hand a medium-sized beaker (600 mL is fine) enough orange juice or other electrolyte mixture or solution to fill the beaker about 2/3 full (tap water often works fine!) a 20-30-cm magnesium strip, coiled at one end or wrapped around a popsicle stick a 20-30-cm copper strip, coiled at one end alligator clips to connect the strips to the battery terminals on the clock a stand against which to lean the setup The demonstration is put together as shown in Figure 3. Connect the magnesium to the "-" contact of the clock and the copper to the "+" contact. Immerse the other ends of the strips into the solution. The clock will start to tick within a few seconds. If it does not work within a short period of time, check that the strips are well connected to the battery terminals, are hooked to the proper poles, and are not touching each other. The clock should keep reasonably close time (in orange juice) for a couple of days, or until the magnesium is nearly completely oxidized. Figure 3.A schematic of the orange juice clock seup. Video of orange juice clock. In video, the copper electrode is on the left and the magnesium electrode is on the right. Video was filmed and