Ultra-sensitive all-optical comagnetometer with laser heating

Abstract Ultra-sensitive comagnetometers, which are designed to detect nuclear-and electron-spin-dependent interaction, have important applications ranging from basic research to inertial navigation systems (INSs). Unfortunately, electric heating, which is typically used in comagnetometers, introduces systematic errors because of the unavoidable generation of a modulated magnetic field. In this study, we investigate and introduce K-Rb-21Ne comagnetometer that uses laser heating for the first time, when operated in the spin-exchange relaxation free (SERF) regime. The performance of the comagnetometer, which is equipped with both laser heating and electric heating, is investigated, and the two heating modes are compared. The temperature characteristics of the comagnetometer are studied theoretically and experimentally. By optimizing the operating temperature and power density of the pump-light, an equivalent rotation sensitivity of 2.5×10^(-7) rad/s/√Hz@1Hz is achieved in laser heating mode. The improvement of laser-heating technology could prove essential to reduce electron relaxation and increase the low-frequency sensitivity of comagnetometers. Our results indicate that laser heating can make comagnetometers more suitable for applications in basic research (fifth force, dark matter, etc.), INSs, and other accurate measurements of electronic and nuclear precession.

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Frequency Encoded All Optical Tri-state Logic Gates NOT and NAND Using Semiconductor Optical Amplifier Based Interferometric Switches

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681209666190620110027 ◽

2020 ◽

Vol 10 (4) ◽

pp. 369-380

Author(s):

K. Maji ◽

K. Mukherjee ◽

A. Raja

Keyword(s):

Semiconductor Optical Amplifier ◽

Extinction Ratio ◽

Optical Power ◽

Logic Gates ◽

Optical Amplifier ◽

All Optical ◽

State Frequency ◽

Spontaneous Noise ◽

First Time ◽

Practical Feasibility

All optical tri-state frequency encoded logic gates NOT and NAND are proposed and numerically investigated using TOAD based interferometric switch for the first time to the best of our knowledge. The optical power spectrum, extinction ratio, contrast ration, and amplified spontaneous noise are calculated to analyze and confirm practical feasibility of the gates. The proposed device works for low switching energy and has high contrast and extinction ratio as indicated in this work.

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The Key Factors of Low-Frequency Electric Heating Assisted Depressurization Method in the Exploiting of Methane Hydrate Sediments

10.2118/205119-ms ◽

2021 ◽

Author(s):

Ermeng Zhao ◽

Jian Hou ◽

Yunkai Ji ◽

Lu Liu ◽

Yongge Liu ◽

...

Keyword(s):

Thermal Conductivity ◽

Heat Capacity ◽

Specific Heat ◽

Specific Heat Capacity ◽

Low Frequency ◽

Electric Heating ◽

Gas Production ◽

Hydrate Decomposition ◽

Hydrate Saturation ◽

Production Behavior

Abstract Natural gas hydrate is widely distributed in the permafrost and marine deposits, and is regarded as an energy resource with great potential. The low-frequency electric heating assisted depressurization (LF-EHAD) has been proven to be an efficient method for exploiting hydrate sediments, which involves complex multi-physics processes, i.e. current conduction, multiphase flow, chemical reaction and heat transfer. The physical properties vary greatly in different hydrate sediments, which may profoundly affect the hydrate decomposition in the LF-EHAD process. In order to evaluate the influence of hydrate-bearing sediment properties on the gas production behavior and energy utilization efficiency of the LF-EHAD method, a geological model was first established based on the data of hydrate sediments in the Shenhu Area. Then, the influence of permeability, porosity, thermal conductivity, specific heat capacity, hydrate saturation and hydrate-bearing layer (HBL) thickness on gas production behavior is comprehensively analyzed by numerical simulation method. Finally, the energy efficiency ratio under different sediment properties is compared. Results indicate that higher gas production is obtained in the high-permeability hydrate sediments during depressurization. However, after the electric heating is implemented, the gas production first increases and then tends to be insensitive as the permeability decreases. With the increasing of porosity, the gas production during depressurization decreases due to the low effective permeability; while in the electric heating stage, this effect is reversed. High thermal conductivity is beneficial to enhance the heat conduction, thus promoting the hydrate decomposition. During depressurization, the gas production is enhanced with the increase of specific heat capacity. However, more heat is consumed to increase the reservoir temperature during electric heating, thereby reducing the gas production. High hydrate saturation is not conducive to depressurization because of the low effective permeability. After electric heating, the gas production increases significantly. High HBL thickness results in a higher gas production during depressurization, while in the electric heating stage, the gas production first increases and then remains unchanged with the increase of thickness, due to the limited heat supply. The comparison results of energy efficiency suggest that electric heating is more advantageous for hydrate sediments with low permeability, high porosity, high thermal conductivity, low specific heat capacity, high hydrate saturation and high HBL thickness. The findings in this work can provide a useful reference for evaluating the application of the LF-EHAD method in gas hydrate sediments.

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Electrochemical Impedance of Hydrogenated Phases of ZnO and CuO Nanoparticles for Electrode Applications

Asian Journal of Physical and Chemical Sciences ◽

10.9734/ajopacs/2020/v8i330116 ◽

2020 ◽

pp. 1-6

Author(s):

L. I. Menegbo ◽

J. L. Konne ◽

N. Boisa

Keyword(s):

Electrochemical Impedance ◽

Sol Gel ◽

Low Frequency ◽

High Gain ◽

High Frequency Region ◽

Nyquist Plots ◽

Eis Measurements ◽

Xrd Patterns ◽

Straight Lines ◽

First Time

The Electrochemical Impedance Spectroscopy (EIS) measurements of Sol-gel synthesized ZnO, CuO and their respective hydrogenated phases (ZnO:H and CuO:H) for a proton-type battery model has been reported for the first time. The XRD patterns confirmed that CuO and ZnO were phase pure with minor impurities. However, that of CuO:H showed mixed phases of CuO and Cu2O with the later appearing prominent. The estimated particle sizes of ZnO, ZnO:H, CuO and CuO:H obtained using Scherrers’ equation were 17.83, 17.75, 21.63 and 15.42 nm respectively, showing remarkable particle size reductions upon hydrogenation as oxygen vacancies were substituted with smaller hydrogen ions. Nyquist plots from the EIS experimental data recorded over a frequency range of 100 kHz – 5 mHz showed expected flat semicircles at the high frequency region and straight lines at the low frequency regions while resistance estimations from the intercepts of the Bode plots were 12.10, 7.80, 16.00 and 10.80 Ω for ZnO, ZnO:H, CuO and CuO:H respectively. It also indicated high gain margins suggesting impressive electrochemical properties for battery applications.

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The significance of Gerta Vrbová's low-frequency stimulation experiment

European Journal of Translational Myology ◽

10.4081/ejtm.2020.9585 ◽

2021 ◽

Cited By ~ 1

Author(s):

Dirk Pette

Keyword(s):

Low Frequency ◽

Basic Research ◽

Contractile Properties ◽

Scientific Cooperation ◽

Low Frequency Stimulation ◽

Slow Twitch Muscle ◽

Frequency Stimulation ◽

Time Courses ◽

Fast Twitch

An inspiring scientific cooperation has come to an end, when Gerta Vrbová, an internationally renowned researcher in the field of neuromuscular interactions, passed away on October 2, 2020. Comparative EMG studies had led Gerta to suggest that different contractile properties of fast- and slow-twitch muscle fibers relate to specific firing patterns of their motoneurones. In support of her hypothesis, long term stimulation of fast-twitch muscles with a stimulus pattern resembling that of slow motoneurones, were shown to induce a pronounced fast-to-slow shift in contractile properties. In our cooperation which started in 1970, and also in cooperation with others, Gerta's experiment proved to be an ideal model for the study of neurally controlled changes in phenotype characteristics at various levels of molecular and cellular organization, their time courses and ranges. It has become most important in basic research on the adaptive potential or plasticity of muscle.

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Mineral assemblage within secondary crystallized melt inclusions in olivine of mantle xenoliths from the Bultfontein kimberlite pipe (Kaapvaal craton, South Africa)

10.5194/egusphere-egu21-4486 ◽

2021 ◽

Author(s):

Alexey Tarasov ◽

Igor Sharygin ◽

Alexander Golovin ◽

Anna Dymshits ◽

Dmitriy Rezvukhin

Keyword(s):

Melt Inclusions ◽

Basic Research ◽

Kimberlite Pipe ◽

Mantle Xenoliths ◽

Mantle Minerals ◽

Source Regions ◽

Basic Research Grant ◽

Carbonate Composition ◽

First Time ◽

Ca Carbonate

For the first time, snapshots of crystallized melts in olivine of sheared garnet peridotite xenoliths from the Bultfontein kimberlite pipe have been studied. This type of xenoliths represents the deepest mantle rocks derived from the base of lithosphere (at depths from 110 to 230 km for various ancient cratons). According to different models, such type of inclusions (secondary) in mantle minerals can be interpreted as relics of the most primitive (i.e., close-to-primary) kimberlite melt that infiltrated into sheared garnet peridotites. In general, these secondary inclusions are directly related to kimberlite magmatism that finally formed the Bultfontein diamond deposits. The primary/primitive composition of kimberlite melt is poorly constrained because kimberlites are ubiquitously contaminated by xenogenic material and altered by syn/post-emplacement hydrothermal processes. Thus, the study of these inclusions helps to significantly advance in solving numerous problems related to the kimberlite petrogenesis.The unexposed melt inclusions were studied by using a confocal Raman spectroscopy. In total, fifteen daughter minerals within the inclusions were identified by this method. Several more phases give distinct Raman spectra, but their determination is difficult due to the lack of similar spectra in the databases. Various carbonates and carbonates with additional anions, alkali sulphates, phosphates and silicates were determined among daughter minerals in the melt inclusions: calcite CaCO3, magnesite MgCO3, dolomite CaMg(CO3)2, eitelite Na2Mg(CO3)2, nyerereite (Na,K)2Ca(CO3)2, gregoryite (Na,K,Ca)2CO3, K-Na-Ca-carbonate (K,Na)2Ca(CO3)2, northupite Na3Mg(CO3)2Cl, bradleyite Na3Mg(PO4)(CO3), burkeite Na6(CO3)(SO4)2, glauberite Na2Ca(SO4)2, thenardite Na2SO4, aphthitalite K3Na(SO4)2, apatite Ca5(PO4)3(OH,Cl,F) and tetraferriphlogopite KMg3FeSi3O10(F,Cl,OH). Note that carbonates are predominant among the daughter minerals in the melt inclusions. Moreover, there are quite a lot of alkali-rich daughter minerals within the inclusions as well. During the last decade, some research groups using different approaches proposed a model of carbonate/alkali&#8209;carbonate composition of kimberlite melts in their source regions. This model contradicts to the generally accepted ultramafic silicate nature of parental kimberlite liquids. This study is a direct support of a new model of carbonatitic composition of kimberlite melts and also shows that alkali contents in kimberlite petrogenesis are usually underestimated.This work was supported by the Russian Foundation for Basic Research (grant No. 20-35-70058).

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Fundamental differences in the radio properties of red and blue quasars: insight from the LOFAR Two-metre Sky Survey (LoTSS)

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa866 ◽

2020 ◽

Vol 494 (3) ◽

pp. 3061-3079 ◽

Cited By ~ 3

Author(s):

D J Rosario ◽

V A Fawcett ◽

L Klindt ◽

D M Alexander ◽

L K Morabito ◽

...

Keyword(s):

Star Formation ◽

Control Sample ◽

Low Frequency ◽

Galactic Nuclei ◽

Sloan Digital Sky Survey ◽

Stellar Objects ◽

Radio Detection ◽

Sky Survey ◽

Quasi Stellar Objects ◽

First Time

ABSTRACT Red quasi-stellar objects (QSOs) are a subset of the luminous end of the cosmic population of active galactic nuclei (AGNs), most of which are reddened by intervening dust along the line of sight towards their central engines. In recent work from our team, we developed a systematic technique to select red QSOs from the Sloan Digital Sky Survey, and demonstrated that they have distinctive radio properties using the Faint Images of the Radio Sky at Twenty centimetres radio survey. Here we expand our study using low-frequency radio data from the LOFAR Two-metre Sky Survey (LoTSS). With the improvement in depth that LoTSS offers, we confirm key results: Compared to a control sample of normal ‘blue’ QSOs matched in redshift and accretion power, red QSOs have a higher radio detection rate and a higher incidence of compact radio morphologies. For the first time, we also demonstrate that these differences arise primarily in sources of intermediate radio loudness: Radio-intermediate red QSOs are × 3 more common than typical QSOs, but the excess diminishes among the most radio-loud systems and the most radio-quiet systems in our study. We develop Monte Carlo simulations to explore whether differences in star formation could explain these results, and conclude that, while star formation is an important source of low-frequency emission among radio-quiet QSOs, a population of AGN-driven compact radio sources is the most likely cause for the distinct low-frequency radio properties of red QSOs. Our study substantiates the conclusion that fundamental differences must exist between the red and normal blue QSO populations.

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Revealing the Bonding Nature in an ALnZnTe3-Type Alkaline-Metal (A) Lanthanide (Ln) Zinc Telluride by Means of Experimental and Quantum-Chemical Techniques

Crystals ◽

10.3390/cryst10100916 ◽

2020 ◽

Vol 10 (10) ◽

pp. 916

Author(s):

Katharina Eickmeier ◽

Simon Steinberg

Keyword(s):

Electronic Structures ◽

Zinc Telluride ◽

Basic Research ◽

Alkaline Metal ◽

X Ray Diffraction ◽

Unique Type ◽

Late Transition Metals ◽

Future Challenges ◽

Late Transition ◽

First Time

Tellurides have attracted an enormous interest in the quest for materials addressing future challenges, because many of them are at the cutting edge of basic research and technologies due to their remarkable chemical and physical properties. The key to the tailored design of tellurides and their properties is a thorough understanding of their electronic structures including the bonding nature. While a unique type of bonding has been recently identified for post-transition-metal tellurides, the electronic structures of tellurides containing early and late-transition-metals have been typically understood by applying the Zintl−Klemm concept; yet, does the aforementioned formalism actually help us in understanding the electronic structures and bonding nature in such tellurides? To answer this question, we prototypically examined the electronic structure for an alkaline metal lanthanide zinc telluride, i.e., RbDyZnTe3, by means of first-principles-based techniques. In this context, the crystal structures of RbLnZnTe3 (Ln = Gd, Tb, Dy), which were obtained from high-temperature solid-state syntheses, were also determined for the first time by employing X-ray diffraction techniques.

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Searching for the largest bound atoms in space

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936562 ◽

2020 ◽

Vol 634 ◽

pp. A138

Author(s):

K. L. Emig ◽

P. Salas ◽

F. de Gasperin ◽

J. B. R. Oonk ◽

M. C. Toribio ◽

...

Keyword(s):

High Redshift ◽

Low Frequency ◽

Significant Feature ◽

Starburst Galaxy ◽

Frequency Spectra ◽

Cassiopeia A ◽

Radio Recombination Lines ◽

Searching Method ◽

Spectral Searching ◽

First Time

Context. Radio recombination lines (RRLs) at frequencies ν < 250 MHz trace the cold, diffuse phase of the interstellar medium, and yet, RRLs have been largely unexplored outside of our Galaxy. Next-generation low-frequency interferometers such as LOFAR, MWA, and the future SKA will, with unprecedented sensitivity, resolution, and large fractional bandwidths, enable the exploration of the extragalactic RRL universe. Aims. We describe methods used to (1) process LOFAR high band antenna (HBA) observations for RRL analysis, and (2) search spectra for RRLs blindly in redshift space. Methods. We observed the radio quasar 3C 190 (z ≈ 1.2) with the LOFAR HBA. In reducing these data for spectroscopic analysis, we placed special emphasis on bandpass calibration. We devised cross-correlation techniques that utilize the unique frequency spacing between RRLs to significantly identify RRLs in a low-frequency spectrum. We demonstrate the utility of this method by applying it to existing low-frequency spectra of Cassiopeia A and M 82, and to the new observations of 3C 190. Results. Radio recombination lines have been detected in the foreground of 3C 190 at z = 1.12355 (assuming a carbon origin) owing to the first detection of RRLs outside of the local universe (first reported in A&A, 622, A7). Toward the Galactic supernova remnant Cassiopeia A, we uncover three new detections: (1) stimulated Cϵ transitions (Δn = 5) for the first time at low radio frequencies, (2) Hα transitions at 64 MHz with a full width at half-maximum of 3.1 km s−1 the most narrow and one of the lowest frequency detections of hydrogen to date, and (3) Cα at vLSR ≈ 0 km s−1 in the frequency range 55–78 MHz for the first time. Additionally, we recover Cα, Cβ, Cγ, and Cδ from the −47 km s−1 and −38 km s−1 components. In the nearby starburst galaxy M 82, we do not find a significant feature. With previously used techniques, we reproduce the previously reported line properties. Conclusions. RRLs have been blindly searched and successfully identified in Galactic (to high-order transitions) and extragalactic (to high redshift) observations with our spectral searching method. Our current searches for RRLs in LOFAR observations are limited to narrow (<100 km s−1) features, owing to the relatively small number of channels available for continuum estimation. Future strategies making use of a wider band (covering multiple LOFAR subbands) or designs with larger contiguous frequency chunks would aid calibration to deeper sensitivities and broader features.

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Particle precipitations during NEIAL events: simultaneous ground based observations at Svalbard

Annales Geophysicae ◽

10.5194/angeo-25-1323-2007 ◽

2007 ◽

Vol 25 (6) ◽

pp. 1323-1336 ◽

Cited By ~ 3

Author(s):

J. Lunde ◽

B. Gustavsson ◽

U. P. Løvhaug ◽

D. A. Lorentzen ◽

Y. Ogawa

Keyword(s):

Minimum Energy ◽

Soft Particle ◽

Particle Precipitation ◽

Characteristic Energy ◽

Incoherent Scatter ◽

Large Numbers ◽

All Optical ◽

Ion Acoustic ◽

Scatter Spectrum ◽

First Time

Abstract. In this paper we present Naturally Enhanced Ion Acoustic Lines (NEIALs) observed with the EISCAT Svalbard Radar (ESR). For the first time, long sequences of NEIALs are recorded, with more than 50 events within an hour, ranging from 6.4 to 140 s in duration. The events took place from ~08:45 to 10:00 UT, 22 January 2004. We combine ESR data with observations of optical aurora by a meridian scanning photometer at wavelengths 557.7, 630.0, 427.8, and 844.6 nm, as well as records from a magnetometer and an imaging riometer. The large numbers of observed NEIALs together with these additional observations, enable us to characterise the particle precipitation during the NEIAL events. We find that the intensities in all optical lines studied must be above a certain level for the NEIALs to appear. We also find that the soft particle precipitation is associated with the down-shifted shoulder in the incoherent scatter spectrum, and that harder precipitation may play a role in the enhancement of the up-shifted shoulder. The minimum energy flux during NEIAL events found in this study was ~3.5 mW/m2 and minimum characteristic energy around 50 eV.

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