Nearly continuous Ca^+ optical clocks with stability at the 10^-18 level

Abstract Optical clocks are important for precise measurements in the field of physics. As reported, both the instability and uncertainty of optical lattice clocks are more than two orders of magnitude smaller than those of the best microwave clocks. Therefore, in the near future, optical clocks could be used to redefine the second. Nevertheless, an optical clock with reliability comparable to microwave clocks has not been achieved thus far. In this paper, we compared the frequencies of two Ca^+ optical clocks that were nearly continuously operated for 31 days. Through the comparison experiment, the frequency stability of a single clocks was found to be 6.3×10^-18 at an averaging time of 520 000 s and 7.9×10^-18 at averaging time of 262000 s, while the operating uptime rate reached more than 90% in the period of around 5 days. Thus, our experiment demonstrated that it is possible to increase the stability of single-ion optical clocks to the 10^-18 level, while still maintaining quasi-continuous operation with a high operating rate. This result further confirms that optical clocks can potentially be used to redefine the second.

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Demonstration of the nearly continuous operation of an 171Yb optical lattice clock for half a year

Metrologia ◽

10.1088/1681-7575/ab9f1f ◽

2020 ◽

Vol 57 (6) ◽

pp. 065021 ◽

Cited By ~ 1

Author(s):

Takumi Kobayashi ◽

Daisuke Akamatsu ◽

Kazumoto Hosaka ◽

Yusuke Hisai ◽

Masato Wada ◽

...

Keyword(s):

Optical Lattice ◽

Continuous Operation ◽

Optical Lattice Clock ◽

Nearly Continuous

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A pulsed-Laser Rb atomic frequency standard for GNSS applications

GPS Solutions ◽

10.1007/s10291-021-01136-9 ◽

2021 ◽

Vol 25 (3) ◽

Author(s):

S. Micalizio ◽

F. Levi ◽

C. E. Calosso ◽

M. Gozzelino ◽

A. Godone

Keyword(s):

Optical Pumping ◽

Frequency Standard ◽

Frequency Stability ◽

Allan Deviation ◽

Rubidium Vapor ◽

Vapor Cell ◽

Continuous Regime ◽

Remarkable Result ◽

Averaging Time ◽

Consequent Improvement

AbstractWe present the results of 10 years of research related to the development of a Rubidium vapor cell clock based on the principle of pulsed optical pumping (POP). Since in the pulsed approach, the clock operation phases take place at different times, this technique demonstrated to be very effective in curing several issues affecting traditional Rb clocks working in a continuous regime, like light shift, with a consequent improvement of the frequency stability performances. We describe two laboratory prototypes of POP clock, both developed at INRIM. The first one achieved the best results in terms of frequency stability: an Allan deviation of σy(τ) = 1.7 × 10−13 τ−1/2, being τ the averaging time, has been measured. In the prospect of a space application, we show preliminary results obtained with a second more recent prototype based on a loaded cavity-cell arrangement. This clock has a reduced size and exhibited an Allan deviation of σy(τ) = 6 × 10−13 τ−1/2, still a remarkable result for a vapor cell device. In parallel, an ongoing activity performed in collaboration with Leonardo S.p.A. and aimed at developing an engineered space prototype of the POP clock is finally mentioned. Possible issues related to space implementation are also briefly discussed. On the basis of the achieved results, the POP clock represents a promising technology for future GNSSs.

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Magic wavelengths of the optical clock transition at 877 nm of barium

Modern Physics Letters B ◽

10.1142/s0217984914501838 ◽

2014 ◽

Vol 28 (23) ◽

pp. 1450183 ◽

Cited By ~ 3

Author(s):

Geng-Hua Yu ◽

Qi-Ming Xu ◽

Chao Zhou ◽

Liang Liang ◽

Long Li ◽

...

Keyword(s):

Theoretical Calculation ◽

Optical Lattice ◽

Optical Lattices ◽

Optical Clock ◽

Light Shift ◽

Laser Trapping ◽

Clock Transition ◽

Linearly Polarized

Magic wavelengths for laser trapping of barium atoms in the optical lattices are investigated while considering the optical clock transition at 877 nm between the 6s21S0 state and 6s5d 1D2 state. Theoretical calculation shows that there are several magic wavelengths with the linearly polarized trapping laser. The trap depths of the optical lattice and the slope of light shift difference with different magic wavelengths are also discussed and analyzed. Some of these magic wavelengths are selected and recommended for the optical lattice trapping laser.

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Mineralogical response of the Mediterranean crustose coralline alga <i>Lithophyllum cabiochae</i> to near-future ocean acidification and warming

10.5194/bg-2016-160 ◽

2016 ◽

Cited By ~ 1

Author(s):

Merinda C. Nash ◽

Sophie Martin ◽

Jean-Pierre Gattuso

Keyword(s):

Ocean Acidification ◽

Crustose Coralline Alga ◽

Coralline Algae ◽

Coralline Alga ◽

Magnesium Calcite ◽

The Mediterranean ◽

One Year ◽

The Stability ◽

Strong Control ◽

Near Future

Abstract. Red calcareous coralline algae are thought to be among organisms the most vulnerable to ocean acidification due to the high solubility of their magnesium calcite skeleton. Although, skeletal mineralogy is proposed to change as CO2 and temperature continues rising, there is currently very little information available on the response of coralline algal carbonate mineralogy to near-future changes in pCO2 and temperature. Here we present results from a one-year controlled laboratory experiment to test mineralogical responses to pCO2 and temperature in the Mediterranean crustose coralline alga (CCA) Lithophyllum cabiochae. Our results show that Mg incorporation is mainly constrained by temperature (+1 mol% MgCO3 for an increase of 3 °C) and there was no response to pCO2. This suggests that L. cabiochae thalli have the ability to buffer calcifying medium against ocean acidification, enabling them to continue to deposit Mg-calcite with a significant mol% MgCO3 under elevated pCO2. Analyses of CCA dissolution chips showed a decrease in Mg content after 1 year for all treatments but this was not affected by pCO2 nor by temperature. Our findings suggest that biological processes exert a strong control on calcification on Mg-calcite and that CCA may be more resilient under rising CO2 than previously thought. However, previously demonstrated increased skeletal dissolution with ocean acidification will still have major consequences for the stability and maintenance of Mediterranean coralligenous habitats.

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Study of Continuos Settling Vessels Operating with Suspensions Previously Floculated

Materials Science Forum ◽

10.4028/www.scientific.net/msf.591-593.358 ◽

2008 ◽

Vol 591-593 ◽

pp. 358-361

Author(s):

J.F. Nunes ◽

J.R. Lira ◽

João Jorge Ribeiro Damasceno

Keyword(s):

Wastewater Treatment ◽

Solid Particle ◽

Aluminum Sulfate ◽

Cylindrical Part ◽

Continuous Operation ◽

Circular Section ◽

Operational Conditions ◽

The Stability ◽

Solid Liquid ◽

Solid Liquid Separation

The settling vessels are equipment destined to solid-liquid separation; usually have continuous operation, with a circular section, presenting one conic and one cylindrical part. They are very used in chemical industries: wastewater treatment, minerals industries; to concentrate or to remove the solids. The solid particle splitting with small granular becomes difficult through the operation of conventional sedimentation. An expedient very used in the industry is the flocculant substance addition, whose objective is to promote the precipitation of particles, with decantation speed is upper than the single one. The present work aim the study of the burst operational conditions that influence the formation and the stability of these aggregates, the flake, the effect of pH and the concentration of flocculant using kaolin suspension and genfloc, that contains aluminum sulfate, as a flocculant; and the capacity of conventional settling vessel, which area of the transversal remains constant, considering this operational conditions.

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A Review of Preparation and Tribological Applications of Pickering Emulsion

Journal of Tribology ◽

10.1115/1.4052480 ◽

2021 ◽

pp. 1-27

Author(s):

Yichen Bao ◽

Kai Liu ◽

Quan Zheng ◽

Lulu Yao ◽

Yufu Xu

Keyword(s):

Pickering Emulsion ◽

Solid Particles ◽

Preparation Methods ◽

Factors Affecting ◽

Long Term Stability ◽

New Strategy ◽

New Type ◽

The Stability ◽

Near Future

Abstract Pickering emulsion is a new type of stable emulsion made by ultra-fine solid particles instead of traditional surfactants as stabilizers, which has received widespread attention in recent years. The preparation methods of stator-rotor homogenization, high-pressure homogenization, and ultrasonic emulsification were compared with others in this work. The main factors affecting the stability of Pickering emulsion are the surface humidity of the solid particles, the polarity of the oil phase, and the oil-water ratio. These factors could affect the nature of the solid particles, the preparation process of Pickering emulsion and the external environment. Consequently, the long-term stability of Pickering emulsion is still a challenge. The tribological investigations of Pickering emulsion were summarized, and the multifunctional Pickering emulsion shows superior prospects for tribological applications. Moreover, the latest development of Pickering emulsion offers a new strategy for smart lubrication in the near future.

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Continuous-Operation Test at Engineering Scale Uranium Crystallizer System

Volume 5: Fuel Cycle and High and Low Level Waste Management and Decommissioning; Computational Fluid Dynamics (CFD), Neutronics Methods and Coupled Codes; Instrumentation and Control ◽

10.1115/icone17-75339 ◽

2009 ◽

Author(s):

Tadahiro Washiya ◽

Toshimitsu Tayama ◽

Kazuhito Nakamura ◽

Kimihiko Yano ◽

Atsuhiro Shibata ◽

...

Keyword(s):

Steady State ◽

Crystallization Process ◽

Continuous Operation ◽

Energy Agency ◽

Monitoring Method ◽

State Test ◽

Operation Test ◽

The Stability ◽

Crystal Accumulation ◽

Steady State Test

Uranium crystallization based on solubility difference is one of the remarkable technologies which can provide simple process to separate uranium in nitric acid solution since the process is mainly controlled by temperature and concentration of solute ions. Japan Atomic Energy Agency (JAEA) and Mitsubishi Materials Corporation (MMC) are developing the crystallization process for elemental technology of FBR fuel reprocessing.[1–3] The uranium (U) crystallization process is a key technology for New Extraction System for TRU Recovery (NEXT) process that was evaluated as the most promising process for future FBR reprocessing.[4–6] We had developed an innovative crystallizer and carried out several fundamental investigations. On the basis of the results, we fabricated an engineering-scale crystallizer and have carried out continuous operation test to investigate the stability of the equipment at steady and non-steady state conditions by using depleted uranium. As for simulating typical failure events in the crystallizer, crystal accumulation and crystal blockage were occurred intentionally, and monitoring method and resume procedure were tried and selected in this work. As the test results, no significant phenomenon was observed in the steady state test. And in the non-steady state test, process fluctuation could be detected by monitoring of screw torque and liquid level in the crystallizer, and all failure events are proven to be recovered by appropriate resumed procedures.

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Design of the High-Speed X-Band Frequency Hopping Source

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.662.231 ◽

2014 ◽

Vol 662 ◽

pp. 231-234

Author(s):

Shuang Zhao ◽

Dian Ren Chen

Keyword(s):

High Speed ◽

Frequency Hopping ◽

Frequency Stability ◽

Band Frequency ◽

X Band ◽

Frequency Source ◽

The Stability ◽

Stability And Accuracy ◽

Low Phase Noise ◽

Communication Equipment

In modern communication system, the spacing of channel becomes ever more finely. For communication equipment, it has made high demands on the stability and accuracy of the frequency. Based on DDS technology, combined with the multiplier circuit, we developed a high-speed X-band frequency hopping source. Experimental results show that this frequency source is with excellent frequency stability and low phase noise.

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