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Search Results: 1 - 10 of 19774 matches for " Alexander Nevsky "
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Locking the frequency of lasers to an optical cavity at the $1.6 \times 10^{-17}$ relative instability level
Qun-Feng Chen,Alexander Nevsky,Stephan Schiller
Physics , 2012, DOI: 10.1007/s00340-012-5014-9
Abstract: We stabilized the frequencies of two independent Nd:YAG lasers to two adjacent longitudinal modes of a high-finesse Fabry-P\'erot resonator and obtained a beat frequency instability of 6.3 mHz at an integration time of 40 s. Referred to a single laser, this is $1.6\times10^{-17}$ relative to the laser frequency, and $1.3\times10^{-6}$ relative to the full width at half maximum of the cavity resonance. The amplitude spectrum of the beat signal had a FWHM of 7.8 mHz. This stable frequency locking is of importance for next-generation optical clock interrogation lasers and fundamental physics tests.
Spectrally narrow, long-term stable optical frequency reference based on a Eu$^{3+}$:Y$_{2}$SiO$_{5}$ crystal at cryogenic temperature
Qun-Feng Chen,Andrei Troshyn,Ingo Ernsting,Steffen Kayser,Sergey Vasilyev,Alexander Nevsky,Stephan Schiller
Physics , 2011, DOI: 10.1103/PhysRevLett.107.223202
Abstract: Using an ultrastable continuous-wave laser at 580 nm we performed spectral hole burning of Eu$^{3+}$:Y$_{2}$SiO$_{5}$ at very high spectral resolution. Essential parameters determining the usefulness as a "macroscopic" frequency reference: linewidth, temperature sensitivity, long-term stability were characterized, using a H-maser stabilized frequency comb. Spectral holes with linewidth as low as 6 kHz were observed and the upper limit of the drift of the hole frequency was determined to be on the order of 5$\pm$3 mHz/s. We discuss necessary requirements for achieving ultra-high-stability in laser frequency stabilization to these spectral holes.
Thermal noise of whispering gallery resonators
Akobuije Chijioke,Qun-Feng Chen,Alexander Yu. Nevsky,Stephan Schiller
Physics , 2011, DOI: 10.1103/PhysRevA.85.053814
Abstract: By direct application of the fluctuation-dissipation theorem, we numerically calculate the fundamental dimensional fluctuations of crystalline CaF2 whispering gallery resonators in the case of structural damping, and the limit that this noise imposes on the frequency stability of such resonators at both room and cryogenic temperatures. We analyze elasto-optic noise - the effect of Brownian dimensional fluctuation on frequency via the strain-dependence of the refractive index - a noise term that has so far not been considered for whispering-gallery resonators. We find that dimensional fluctuation sets a lower limit of 1E-16 to the Allan deviation for a 10-millimeter-radius sphere at 5 K, predominantly via induced fluctuation of the refractive index.
A silicon single-crystal cryogenic optical resonator
Eugen Wiens,Qun-Feng Chen,Ingo Ernsting,Heiko Luckmann,Ulrich Rosowski,Alexander Nevsky,Stephan Schiller
Physics , 2014, DOI: 10.1364/OL.39.003242
Abstract: We report on the demonstration and characterization of a silicon optical resonator for laser frequency stabilization, operating in the deep cryogenic regime at temperatures as low as 1.5 K. Robust operation was achieved, with absolute frequency drift less than 20 Hz over 1 hour. This stability allowed sensitive measurements of the resonator thermal expansion coefficient ($\alpha$). We found $\alpha=4.6\times10^{-13}$ ${\rm K^{-1}}$ at 1.6 K. At 16.8 K $\alpha$ vanishes, with a derivative equal to $-6\times10^{-10}$ ${\rm K}^{-2}$. The temperature of the resonator was stabilized to a level below 10 $\mu$K for averaging times longer than 20 s. The sensitivity of the resonator frequency to a variation of the laser power was also studied. The corresponding sensitivities and the expected Brownian noise indicate that this system should enable frequency stabilization of lasers at the low-$10^{-17}$ level.
Demonstration of a Transportable 1 Hz-Linewidth Laser
Stefan Vogt,Christian Lisdat,Thomas Legero,Uwe Sterr,Ingo Ernsting,Alexander Nevsky,Stephan Schiller
Physics , 2010, DOI: 10.1007/s00340-011-4652-7
Abstract: We present the setup and test of a transportable clock laser at 698 nm for a strontium lattice clock. A master-slave diode laser system is stabilized to a rigidly mounted optical reference cavity. The setup was transported by truck over 400 km from Braunschweig to D\"usseldorf, where the cavity-stabilized laser was compared to a stationary clock laser for the interrogation of ytterbium (578 nm). Only minor realignments were necessary after the transport. The lasers were compared by a Ti:Sapphire frequency comb used as a transfer oscillator. The thus generated virtual beat showed a combined linewidth below 1 Hz (at 1156 nm). The transport back to Braunschweig did not degrade the laser performance, as was shown by interrogating the strontium clock transition.
Proton irradiation robustness of dielectric mirrors for high-finesse Fabry-Pérot resonators in the near-infrared spectral range
Qun-Feng Chen,Alexander Nevsky,Stephan Schiller,Erwin Portuondo Campa,Steve Lecomte,David Parker
Physics , 2013, DOI: 10.1007/s00340-013-5704-y
Abstract: We demonstrate that a proton irradiation with fluences of $3.6\times10^{10}$/cm$^{2}$ at low energy ($<$ 36 MeV) and $1.46 \times 10^{10}$/cm$^{2}$ at high energy (40 MeV and 90 MeV combined) on the dielectric mirrors of Fabry-P\'erot cavities with a finesse of about 700 000 causes less than 5% change in the finesse. Furthermore, no influence on the coupling efficiency to the cavities was observed, the efficiency being approximately 70%. The irradiation was carried out with a spectrum approximating the proton energy spectrum of a highly elliptic Earth orbit with duration of 5 years, proposed for the Space-Time Explorer and Quantum Equivalence Space Test (STE-QUEST) mission [\url{http://sci.esa.int/ste-quest/}].
A compact, robust, and transportable ultra-stable laser with a fractional frequency instability of $1\times10^{-15}$
Qun-Feng Chen,Alexander Nevsky,Marco Cardace,Stephan Schiller,Thomas Legero,Sebastian H?fner,Andre Uhde,Uwe Sterr
Physics , 2014, DOI: 10.1063/1.4898334
Abstract: We present a compact and robust transportable ultra-stable laser system with minimum fractional frequency instability of $1\times10^{-15}$ at integration times between 1 to 10 s. The system was conceived as a prototype of a subsystem of a microwave-optical local oscillator to be used on the satellite mission STE-QUEST (Space-Time Explorer and QUantum Equivalence Principle Space Test, http://sci.esa.int/ste-quest/). It was therefore designed to be compact, to sustain accelerations occurring during rocket launch, to exhibit low vibration sensitivity, and to reach a low frequency instability. Overall dimensions of the optical system are $40\textrm{ cm}\times20\textrm{ cm}\times30\textrm{ cm}$. The acceleration sensitivities of the optical frequency in the three directions were measured to be $1.7\times10^{-11}/g$, $8.0\times10^{-11}/g$, and $3.9\times10^{-10}/g$, and the absolute frequency instability was determined via a three-cornered hat measurement. The design is also appropriate and useful for terrestrial applications.
Russian meteorite Bronze Age (rock record)
Larisa Vodolazhskaya,Mikhail Nevsky
Physics , 2013,
Abstract: This paper presents the results of a study of petroglyphs found in the quartzite grotto near the Skelnovsky small village in the Northern Black Sea in the South of Russia. The aim of the study was the analysis and interpretation of the Early Bronze Age petroglyphs using archaeoastronomical methods. The article presents a comparative analysis of Skelnovsky grotto ancient images and contemporary eyewitness accounts of the Sikhote-Alin meteorite fall and meteorite shower. Some petroglyphs were interpreted by us using ethnographic and folklore material. In this study, the magnetic declination for the geographical coordinates Skelnovsky farm was calculated, and the projection of the whole picture Skelnovskih petroglyphs on the topographical map of the area was built. The proposed location of the meteorite fall was determined with this projection. It is confirmed by satellite pictures, on which are the distinguishable terrain features, typical for the meteorite fall, are visible including the possible impact crater, and the corresponding symbols on a topographical map. The studies in the article conclude the astronomical character of the main content of the Skelnovsky petroglyphs picture which depicts the fall of a large meteoroid (bolide), similar to the Sikhote-Alin meteorite, accompanied by a meteorite shower. After a comparative analysis of the images in Sklenovsky Grotto it was discovered that the petroglyph is a copy of the figure depicted on the famous Mesopotamic clay tablet YBC 7289. We speculate that this figure is a prototype of an important building used either for ritual or farm purposes, typical for the Bronze Age and distributed as in Mesopotamia, as also on the coast of the Northern Black Sea. archaeoastronomy, petroglyphs, rock art, meteoroid, meteorite shower, impact crater, Babylonian clay tablet YBC 7289
Robust frequency stabilization of multiple spectroscopy lasers with large and tunable offset frequencies
Alexander Nevsky,Soroosh Alighanbari,Qun-Feng Chen,Ingo Ernsting,Sergey Vasilyev,Stephan Schiller,Geoffrey Barwood,Patrick Gill,Nicola Poli,Guglielmo M. Tino
Physics , 2013, DOI: 10.1364/OL.38.004903
Abstract: We demonstrate a compact and robust device for simultaneous absolute frequency stabilization of three diode lasers whose carrier frequencies can be chosen freely relative to the reference. A rigid ULE multi-cavity block is employed, and, for each laser, the sideband locking technique is applied. Useful features of the system are a negligible lock error, computer control of frequency offset, wide range of frequency offset, simple construction, and robust operation. One concrete application is as a stabilization unit for the cooling and trapping lasers of a neutral atom lattice clock. The device significantly supports and improves the operation of the clock. The laser with the most stringent requirements imposed by this application is stabilized to a linewidth of 70 Hz, and a residual frequency drift less than 0.5 Hz/s. The carrier optical frequency can be tuned over 350 MHz while in lock.
The water clock of the Bronze Age (Northern Black Sea Coast)
Larisa N. Vodolazhskaya,Anatoliy N. Usachuk,Mikhail Yu. Nevsky
Physics , 2015,
Abstract: In the article presents the results of the multidisciplinary study conducted with the help of archaeological, physical and astronomical methods. The aim of the study was to analyze and interpret marks and drawings applied to the surface of the vessel of the Bronze Age (Srubna culture) found near the Staropetrovsky village (Donetsk region, Ukraine) near the border between the Donetsk and Lugansk regions. The carried out calculations and measurements possible to prove that staropetrovsky vessel is the most ancient water clock, discovered on the territory of Europe, and have approximately the same age as the oldest known ancient Egyptian water clock. Such vessels - water clocks were needed for Srubna population to mark sundial, which had recently been discovered in the Northern Black Sea Coast. Based on the analysis of marks on the outside of the vessel, it was revealed that Staropetrovsky vessel is unique ancient complex device for measuring time and at the same time using a water clock, and with the help of a sundial, allows to monitor of the uneven apparent motion of the Sun long before the existing written evidence about such monitoring. Series of marks on the outer surface of the vessel and on its corolla was associated with the star Sirius and its heliacal rising. Given in this paper the results of astronomical calculations allow to state that astronomical beginning of the year recorded since the heliacal rising of Sirius at the Srubna population of the Northern Black Sea Coast. Keywords: archaeoastronomy, modeling, Srubna culture, vessel, marks, water clock, sundial, equation of time, Sirius, heliacal rising.
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