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1
Pumpe, Daniel, Martin Reinecke, and Torsten A. Enßlin. "Denoising, deconvolving, and decomposing multi-domain photon observations." Astronomy & Astrophysics 619 (November 2018): A119. http://dx.doi.org/10.1051/0004-6361/201832781.
Повний текст джерелаАнотація:
Astronomical imaging based on photon count data is a non-trivial task. In this context we show how to denoise, deconvolve, and decompose multi-domain photon observations. The primary objective is to incorporate accurate and well motivated likelihood and prior models in order to give reliable estimates about morphologically different but superimposed photon flux components present in the data set. Thereby we denoise and deconvolve photon counts, while simultaneously decomposing them into diffuse, point-like and uninteresting background radiation fluxes. The decomposition is based on a probabilistic hierarchical Bayesian parameter model within the framework of information field theory (IFT). In contrast to its predecessor D3PO, D4PO reconstructs multi-domain components. Thereby each component is defined over its own direct product of multiple independent domains, for example location and energy. D4PO has the capability to reconstruct correlation structures over each of the sub-domains of a component separately. Thereby the inferred correlations implicitly define the morphologically different source components, except for the spatial correlations of the point-like flux. Point-like source fluxes are spatially uncorrelated by definition. The capabilities of the algorithm are demonstrated by means of a synthetic, but realistic, mock data set, providing spectral and spatial information about each detected photon. D4PO successfully denoised, deconvolved, and decomposed a photon count image into diffuse, point-like and background flux, each being functions of location as well as energy. Moreover, uncertainty estimates of the reconstructed fields as well as of their correlation structure are provided employing their posterior density function and accounting for the manifolds the domains reside on.
2
Li, Wei, Ling Lin, Lei Bao, Longfei Zhao, and Gang Li. "Monte Carlo simulation of photon migration in multi-component media." Optical and Quantum Electronics 47, no. 7 (November 8, 2014): 1919–31. http://dx.doi.org/10.1007/s11082-014-0058-1.
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Huang, Ying, Yusheng Zhang, Yuming Su, Zhenghao Zhai, Jiawei Chen, and Cheng Wang. "Two-photon induced polymerization in a porous polymer film to create multi-layer structures." Chemical Communications 57, no. 37 (2021): 4516–19. http://dx.doi.org/10.1039/d1cc01383a.
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Kastner, Alexander, Greta Koumarianou, Pavle Glodic, Peter C. Samartzis, Nicolas Ladda, Simon T. Ranecky, Tom Ring, et al. "High-resolution resonance-enhanced multiphoton photoelectron circular dichroism." Physical Chemistry Chemical Physics 22, no. 14 (2020): 7404–11. http://dx.doi.org/10.1039/d0cp00470g.
Повний текст джерелаАнотація:
By combining molecular beam techniques with high resolution resonance enhanced multi photon ionization followed by angular resolved photoelectron detection we pave the way for enantiomer specific molecular identification in multi-component mixtures.
5
Rebufello, E., F. Piacentini, M. López, R. A. Kirkwood, I. Ruo Berchera, M. Gramegna, G. Brida, et al. "Towards a standard procedure for the measurement of the multi-photon component in a CW telecom heralded single-photon source." Metrologia 56, no. 2 (February 22, 2019): 025004. http://dx.doi.org/10.1088/1681-7575/ab022e.
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Streed, E. W., B. G. Norton, J. J. Chapman, and D. Kielpinski. "Scalable, efficient ion-photon coupling with phase Fresnel lenses for large-scale quantum computing." Quantum Information and Computation 9, no. 3&4 (March 2009): 203–14. http://dx.doi.org/10.26421/qic9.3-4-2.
Повний текст джерелаАнотація:
Efficient ion-photon coupling is an important component for large-scale ion-trap quantum computing. We propose that arrays of phase Fresnel lenses (PFLs) are a favorable optical coupling technology to match with multi-zone ion traps. Both are scalable technologies based on conventional micro-fabrication techniques. The large numerical apertures (NAs) possible with PFLs can reduce the readout time for ion qubits. PFLs also provide good coherent ion-photon coupling by matching a large fraction of an ion's emission pattern to a single optical propagation mode (TEM$_{00}$). To this end we have optically characterized a large numerical aperture phase Fresnel lens (NA=0.64) designed for use at 369.5 nm, the principal fluorescence detection transition for Yb$^+$ ions. A diffraction-limited spot $w_0=350\pm15$ nm ($1/e^2$ waist) with mode quality $M^2= 1.08\pm0.05$ was measured with this PFL. From this we estimate the minimum expected free space coherent ion-photon coupling to be 0.64\%, which is twice the best previous experimental measurement using a conventional multi-element lens. We also evaluate two techniques for improving the entanglement fidelity between the ion state and photon polarization with large numerical aperture lenses.
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Kamada, Ayuki, Hee Jung Kim, Jong-Chul Park, and Seodong Shin. "Manifesting hidden dynamics of a sub-component dark matter." Journal of Cosmology and Astroparticle Physics 2022, no. 10 (October 1, 2022): 052. http://dx.doi.org/10.1088/1475-7516/2022/10/052.
Повний текст джерелаАнотація:
Abstract We emphasize the distinctive cosmological dynamics in multi-component dark-matter scenarios and their impact on probing a sub-dominant component of dark matter. The dynamics originate from the conversion among different dark-matter components. We find that the temperature of the self-interacting sub-component dark matter is significantly enhanced by the dark-matter annihilation into the sub-component. The same annihilation sharply increases the required annihilation cross section for the sub-component as we consider a smaller relative abundance fraction among the dark-matter species. Because of the enhanced temperature and couplings of the sub-component, contrary to a naive expectation, the sub-component with smaller abundance fractions tends to be disfavored by dark-matter direct/indirect-detection experiments and cosmological observations. We demonstrate this by taking a dark photon portal scenario for the sub-component at the sub-GeV mass scale. For the abundance fraction ≳ 10 %, the enhanced temperature of the sub-component is subject to warm dark matter constraints which are complementary to the parameter space probed by accelerator-based experiments. Smaller abundance fractions tend to be disfavored by accelerator-based experiments due to the enhanced coupling to Standard Model particles.
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Nash, B., D. T. Abell, R. Nagler, P. Moeller, M. Keilman, I. Pogorelov, N. Goldring, et al. "Combining diagnostics, modeling, and control systems for automated alignment of the TES beamline." Journal of Physics: Conference Series 2380, no. 1 (December 1, 2022): 012103. http://dx.doi.org/10.1088/1742-6596/2380/1/012103.
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Abstract X-ray beamlines are essential components of all synchrotron light sources. Practical operations involve frequent variation in beamline component positions and orientation, particularly when photon beam parameters shift due to experimental needs, or due to variations in the incoming photon beam. The alignment process can be time consuming and takes away from valuable beam time for experimental data collection. We describe progress in the automation of certain alignment tasks on the tender-energy X-ray spectroscopy (TES) beamline at the National Synchrotron Light Source II (NSLS-II). The beamline is controlled using the BlueSky software in which high level experimental plans guide the beamline components during an experiment. Numerous software packages exist for beamline modeling, and they may be tied to the beamline control system using a package we are continuing to develop called Sirepo-Bluesky. The photon beam distribution may be measured with fluorescent screens, and a relation between beam and machine state can be found by varying the mirror and aperture settings over a multi-dimensional range. We describe the results of such parameter varying measurements and how we are combining Sirepo-Bluesky with machine learning methods and reduced models to automate mirror alignment on the TES beamline.
9
KODAMA, HIDEO, and MISAO SASAKI. "EVOLUTION OF ISOCURVATURE PERTURBATIONS II: RADIATION-DUST UNIVERSE." International Journal of Modern Physics A 02, no. 02 (April 1987): 491–560. http://dx.doi.org/10.1142/s0217751x8700020x.
Повний текст джерелаАнотація:
Density perturbations in a universe in which matter consists of noninteracting nonrelativistic particles(dust) and strongly coupled photon-baryon fluid(radiation) are analyzed in terms of the gauge-invariant formalism extended to a multi-component system. Detailed analytic estimate is presented for the time evolution of both primordially adiabatic and primordially isocurvature perturbations. In particular, analytic formulas for characteristic scales appearing in the transfer functions are derived. The evolutionary behavior of these two types of perturbations are compared and the origins of their differences and similarities are clarified.
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Liprandi, Silvia, Michael Mayerhofer, Saad Aldawood, Tim Binder, George Dedes, Agnese Miani, Dennis R. Schaart, Ingrid I. Valencia Lozano, Katia Parodi, and Peter G. Thirolf. "Sub-3mm spatial resolution from a large monolithic LaBr3 (Ce) scintillator." Current Directions in Biomedical Engineering 3, no. 2 (September 7, 2017): 655–59. http://dx.doi.org/10.1515/cdbme-2017-0138.
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AbstractA Compton camera prototype for ion beam range monitoring via prompt (< 1 ns) gamma detection in hadron therapy is being developed and characterized at the Medical Physics Department of LMU Munich. The system consists of a large (50x50x30 mm3) monolithic LaBr3(Ce) scintillation crystal as absorber component to detect the multi-MeV Compton scattered photons, together with a stack of 6 double-sided silicon strip detectors (DSSSD) acting as scatterer component. Key ingredient of the γ-source reconstruction is the determination of the γ-ray interaction position in the scintillator, which is read out by a 256-fold segmented multi-anode photomultiplier tube (PMT). From simulations an angular resolution of about 1.5o for the photon source reconstruction can be expected for the energy range around 3 – 5 MeV, provided that a spatial resolution of 3 mm can be reached in the absorbing scintillator [1]. Therefore, particular effort was dedicated to characterize this latter property as a function of the γ-ray energy. Intense, tightly collimated 137Cs and 60Co photon sources were used for 2D irradiation scans (step size 0.5 mm) as prerequisite for studying the performance of the “k-Nearest-Neighbors” algorithm developed at TU Delft [2] (together with its variant ”Categorical Average Pattern”, CAP) and extending its applicability into the energy range beyond the original 511 keV. In this paper we present our most recent interaction position analysis in the absorbing scintillator, leading to a considerably improved value for the spatial resolution: systematic studies were performed as a function of the k-NN parameters and the PMT segmentation. A trend of improving spatial resolution with increasing photon energy was confirmed, resulting in the realization of the presently optimum spatial resolution of 2.9(1) mm @1.3 MeV, thus reaching the design specifications of the Compton camera absorber. The specification goal was reached also for a reduced PMT segmentation of 8x8 anode segments (each with 6x6 mm2 active area), thus allowing to reduce the complexity of the signal processing while preserving the performance.
11
Zhang, S. N. "High Energy Continuum Spectra from X-Ray Binaries." International Astronomical Union Colloquium 163 (1997): 41–52. http://dx.doi.org/10.1017/s0252921100042482.
Повний текст джерелаАнотація:
AbstractA variety of high energy (>1 keV) spectra have been observed in recent years from Black Hole (BH) and Neutron Star (NS) X-ray Binaries (XB). Some common physical components exist between BHXBs and NSXBs, resulting in some high energy spectral features. A common component between a BHXB and a weakly magnetized NSXB is the inner accretion disk region extending very close to the surface (for a NS) or the horizon (for a BH). The inner disk radiation can be described by a multi-color blackbody (MCB) spectral model. The surface radiation of the NS can be approximated by a Single Color Blackbody (SCB) spectrum. For a strongly magnetized NSXB, the high energy emission is from its magnetosphere, characterised by a thermal bremsstrahlung (TB) spectrum. In both BHXBs and weakly magnetized NSXBs, a hot electron cloud may exist, producing the hard X-ray power law (photon index −1.5 to −2.0) with thermal cutoff (50–200 keV). It has been recently proposed that a converging flow may be formed near the horizon of a BH, producing a softer power law (photon index about −2.5) without cutoff up to several hundred keV. Based on these concepts we also discuss possible ways to distinguish between BH and NS XBs. Finally we discuss briefly spectral state transitions in both BH and NS XBs.
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Chang, Huibin, Ziqin Rong, Pablo Enfedaque, and Stefano Marchesini. "Iterative X-ray spectroscopic ptychography." Journal of Applied Crystallography 53, no. 4 (July 8, 2020): 937–48. http://dx.doi.org/10.1107/s1600576720006354.
Повний текст джерелаАнотація:
Spectroscopic ptychography is a powerful technique to determine the chemical composition of a sample with high spatial resolution. In spectro-ptychography, a sample is rastered through a focused X-ray beam with varying photon energy so that a series of phaseless diffraction data are recorded. Each chemical component in the material under investigation has a characteristic absorption and phase contrast as a function of photon energy. Using a dictionary formed by the set of contrast functions of each energy for each chemical component, it is possible to obtain the chemical composition of the material from high-resolution multi-spectral images. This paper presents SPA (spectroscopic ptychography with alternating direction method of multipliers), a novel algorithm to iteratively solve the spectroscopic blind ptychography problem. First, a nonlinear spectro-ptychography model based on Poisson maximum likelihood is designed, and then the proposed method is constructed on the basis of fast iterative splitting operators. SPA can be used to retrieve spectral contrast when considering either a known or an incomplete (partially known) dictionary of reference spectra. By coupling the redundancy across different spectral measurements, the proposed algorithm can achieve higher reconstruction quality when compared with standard state-of-the-art two-step methods. It is demonstrated how SPA can recover accurate chemical maps from Poisson-noised measurements, and its enhanced robustness when reconstructing reduced-redundancy ptychography data using large scanning step sizes is shown.
13
Middei, R., S. Bianchi, M. Cappi, P. O. Petrucci, F. Ursini, N. Arav, E. Behar, et al. "Multi-wavelength campaign on NCG 7469." Astronomy & Astrophysics 615 (July 2018): A163. http://dx.doi.org/10.1051/0004-6361/201832726.
Повний текст джерелаАнотація:
We conducted a multi-wavelength 6-month campaign to observe the Seyfert Galaxy NGC 7469, using the space-based observatories HST, Swift, XMM-Newton and NuSTAR. We report the results of the spectral analysis of the seven simultaneous XMM-Newton and NuSTAR observations. The source shows significant flux variability within each observation, but the average flux is less variable among the different pointings of our campaign. Our spectral analysis reveals a prominent narrow neutral Fe Kα emission line in all the spectra and weaker contributions from Fe Kβ, neutral Ni Kα, and ionized iron. We find no evidence for variability or relativistic effects acting on the emission lines, which indicates that they originate from distant material. In the joint analysis of XMM-Newton and NuSTAR data, a constant photon index is found (Γ = 1.78 ± 0.02) together with a high energy cut-off Ecut = 170−40+60 keV. Adopting a self-consistent Comptonization model, these values correspond to an average coronal electron temperature of kT = 45−12+15 keV and, assuming a spherical geometry, an optical depth τ = 2.6 ± 0.9. The reflection component is consistent with being constant and the reflection fraction is in the range R = 0.3−0.6. A prominent soft excess dominates the spectra below 4 keV. This is best fit with a second Comptonization component, arising from a warm corona with an average kT = 0.67 ± 0.03 keV and a corresponding optical depth τ = 9.2 ± 0.2.
14
Rohith, M., C. Sudheesh, and R. Rajeev. "Entanglement dynamics of quantum states generated by a Kerr medium and a beam splitter." Modern Physics Letters B 30, no. 02 (January 20, 2016): 1550269. http://dx.doi.org/10.1142/s0217984915502693.
Повний текст джерелаАнотація:
We study theoretically the dynamics of entangled states created in a beam splitter with a nonlinear Kerr medium placed into one input arm. Entanglement dynamics of initial classical and nonclassical states are studied and compared. Signatures of revival and fractional revival phenomena exhibited during the time evolution of states in the Kerr medium are captured in the entangled states produced by the beam splitter. Dynamics of entanglement shows local minima at the instants of fractional revivals. These minima correspond to the generation of two-component Schrödinger cat states or multi-component Schrödinger cat-like states if the initial state considered is a coherent state. Maximum entanglement is obtained at the instants of collapses of wave packets in the medium. Our analysis shows increase in entanglement with increase in the degree of nonclassicality of the initial states considered. We show that the states generated at the output of the beam splitter using initial nonclassical states are more robust against decoherence due to photon absorption by an environment than those formed by an initial classical state.
15
HIGO, S., M. IMAI, Y. HAKURAKU, I. KAWANO, and T. OGUSHI. "JOSEPHSON JUNCTION USING A CROSSED CONTACT OF SUPERCONDUCTING Bi(Pb)-Sr-Ca-Cu-O THIN FILM WITH 110 K-PHASE." Modern Physics Letters B 05, no. 14n15 (June 1991): 985–92. http://dx.doi.org/10.1142/s0217984991001209.
Повний текст джерелаАнотація:
Bi 1.75 Pb 0.17 Sr 2 Ca 2.1 Cu 3.2 O y thin films with zero resistivity at 115 K, were prepared by dc magnetron sputtering and subsequent high-temperature annealing. Josephson bridges were fabricated by crossed contact of two cleaved planes of the thin films. Self-induced current steps and multi photon-assisted tunneling currents due to quasi-particles tunneling across the oxide gap barriers were observed. It was proved that the formation of the oxide gap barriers was due to oxidation of the Cu component and the extrication of Ca near the crossed contact of the thin film by soaking the thin film in liquid nitrogen. It seems possible to fabricate smaller bridge with a single junction by the use of thinner as-grown films with smoother surfaces.
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Mondal, Samaresh, Agata Różańska, Eleonora Veronica Lai, and Barbara De Marco. "An extreme ultraluminous X-ray source X-1 in NGC 5055." Astronomy & Astrophysics 642 (October 2020): A94. http://dx.doi.org/10.1051/0004-6361/202038684.
Повний текст джерелаАнотація:
Aims. We analysed multi-epoch X-ray data of the ultraluminous X-ray source NGC 5055 X-1, with luminosity up to 2.32 × 1040 erg s−1, to constrain the physical parameters of the source. Methods. We performed a timing and spectral analysis of Chandra and XMM-Newton observations. We used spectral models that assume the emission is from an accreting black hole system. We fit the data with a multicolour disk combined with a powerlaw or a thermal Comptonization (NTHCOMP) component and compared those fits with a slim disk model. Results. The light curves of the source do not show significant variability. From the hardness ratios (3–10 keV/0.3–3 keV flux), we infer that the source is not spectrally variable. We found that the photon index is tightly, positively correlated with the unabsorbed 0.3–10 keV flux and the hydrogen column density. Furthermore, the temperature emissivity profile indicates a deviation from the standard sub-Eddington thin disk model. The source shows an inverse correlation between luminosity and inner disk temperature in all fitted models. Conclusions. Our analysis favours the source to be in an ultraluminous soft state. The positive correlations between the photon index and the flux as well as between the photon index and the hydrogen column density may suggest the source is accreting at high Eddington ratios and might indicate the presence of a wind. The inverse luminosity relation with the inner disk temperature for all spectral models may indicate that the emission is geometrically beamed by an optically thick outflow.
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Razzaq, Muhammad Yasar, Joamin Gonzalez-Gutierrez, Gregory Mertz, David Ruch, Daniel F. Schmidt, and Stephan Westermann. "4D Printing of Multicomponent Shape-Memory Polymer Formulations." Applied Sciences 12, no. 15 (August 5, 2022): 7880. http://dx.doi.org/10.3390/app12157880.
Повний текст джерелаАнотація:
Four-dimensional (4D) printing technology, as a next-generation additive manufacturing method, enables printed objects to further change their shapes, functionalities, or properties upon exposure to external stimuli. The 4D printing of programmable and deformable materials such as thermo-responsive shape-memory polymers (trSMPs), which possess the ability to change shape by exposure to heat, has attracted particular interest in recent years. Three-dimensional objects based on SMPs have been proposed for various potential applications in different fields, including soft robotics, smart actuators, biomedical and electronics. To enable the manufacturing of complex multifunctional 3D objects, SMPs are often coupled with other functional polymers or fillers during or before the 3D printing process. This review highlights the 4D printing of state-of-the-art multi-component SMP formulations. Commonly used 4D printing technologies such as material extrusion techniques including fused filament fabrication (FFF) and direct ink writing (DIW), as well as vat photopolymerization techniques such as stereolithography (SLA), digital light processing (DLP), and multi-photon polymerization (MPP), are discussed. Different multicomponent SMP systems, their actuation methods, and potential applications of the 3D printed objects are reviewed. Finally, current challenges and prospects for 4D printing technology are summarized.
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Middei, R., F. Vagnetti, F. Tombesi, S. Bianchi, A. Marinucci, F. Ursini, and A. Tortosa. "NuSTAR view of the Seyfert galaxy HE 0436-4717." Astronomy & Astrophysics 618 (October 2018): A167. http://dx.doi.org/10.1051/0004-6361/201833598.
Повний текст джерелаАнотація:
We present the multi-epoch spectral analysis of HE 0436-4717, a bright Seyfert 1 galaxy serendipitously observed by the high energy satellite NuSTAR four times between December 2014 and December 2015. The source flux shows modest variability within each pointing and among the four observations. Spectra are well modelled in terms of a weakly variable primary power law with constant photon index (Γ = 2.01 ± 0.08). A constant narrow Fe Kα emission line suggests that this feature has an origin far from the central black hole, while a broad relativistic component is not required by the data. The Compton reflection component is also constant in flux with a corresponding reflection fraction R = 0.7+0.2−0.3. The iron abundance is compatible with solar (AFe = 1.2+1.4−0.4), and a lower limit for the high energy cut-off Ec > 280 keV is obtained. Adopting a self-consistent model accounting for a primary Comptonized continuum, we obtain a lower limit for the hot corona electron temperature kTe > 65 keV and a corresponding upper limit for the coronal optical depth of τe < 1.3. The results of the present analysis are consistent with the locus of local Seyfert galaxies in the kTe − τe and temperature-compactness diagrams.
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Osorio-Clavijo, N., O. González-Martín, I. E. Papadakis, J. Masegosa, and L. Hernández-García. "The inner view of NGC 1052 using multiple X-ray observations." Monthly Notices of the Royal Astronomical Society 491, no. 1 (November 19, 2019): 29–38. http://dx.doi.org/10.1093/mnras/stz2785.
Повний текст джерелаАнотація:
ABSTRACT In this paper, we present a multi-epoch analysis of NGC 1052, a prototypical low-luminisity active galactic nucleus, using XMM–Newton, Suzaku and NuSTAR observations taken from 2001 to 2017. This is the first time that results from NuSTAR observations have been reported for NGC 1052. Regarding technical aspects, we found a wavelength-dependent calibration issue between simultaneous XMM–Newton and NuSTAR spectra, characterized by a change in the photon index of $\rm { \Gamma _{NuSTAR}- \Gamma _{XMM-Newton}=0.17\pm 0.04}$. We use ancillary Chandra data to decontaminate the nuclear spectrum from circumnuclear contributors. We find that two baseline models can fit the broad (0.5–50 keV) X-ray spectrum of the source. One consists of a power-law-like continuum that is absorbed by a uniform absorber, and is reflected by neutral material, and a separate power-law component in the soft band. The second model consists of a clumpy absorber. The reflection component is still present, but not the soft-band power law. Instead, absorption by a warm absorber is necessary to fit the spectra. This is the first time that a reflection component has been established in this object, thanks to high-energy data from NuSTAR. This component is constant in flux and shape, supporting the idea that it is produced away from the central source (probably in the torus). We find flux, spectral slope and absorption variations on time-scales of months to years. We also find that a patchy absorber can explain the behaviour of this source better, as it is ∼200 times more likely than the uniform absorber and yields smaller intrinsic variations.
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Mishra, Manoj K., Hari Prakash, and Vibhuti B. Jha. "Ququats as superposition of coherent states and their application in quantum information processing." International Journal of Quantum Information 19, no. 02 (March 2021): 2150013. http://dx.doi.org/10.1142/s0219749921500131.
Повний текст джерелаАнотація:
Superposition of optical coherent states (SCS) [Formula: see text], possessing opposite phases, plays an important role as qubits in quantum information processing tasks like quantum computation, teleportation, key distribution, etc. and are of fundamental importance in testing quantum mechanics. Passage of such SCS from a 50:50 beam splitter leads to generation of entangled coherent states. Recently, ququats and qutrits defined in four- and three-dimensional Hilbert space, respectively, have attracted much attention as they offer advantage in secure quantum communication. However, practical utilization of these advantages essentially requires physical realization of quantum optical ququats and qutrits. Here, we define four new multi-photonic states (MPS) with [Formula: see text] (here, [Formula: see text] or 3 and [Formula: see text]) numbers of photon and show how the SCS can be used to encode ququat using these MPS as basis vectors of a four-dimensional Hilbert space. When these MPS fall upon a 50:50 beam splitter, the resulting states are bipartite four-component entangled coherent states (BFECS) equivalently representing the entangled ququats. We briefly discuss the photon statistical properties of such MPS and BFECS. We show that these MPS and BFECS can be synthesized using even coherent states as input to an interferometer. We give a simple linear optical protocol for almost perfect teleportation of a ququat encoded in SCS with the aid of BFECS as quantum channel. We also describe how these ququats can be used for realization of higher-dimensional BB84 protocol to increase the security of quantum key distribution. Finally, we discuss the possible advantages of using SCS as ququats and BFECS as quantum channel in different quantum information processing tasks.
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Guevara, C., J. Stutzki, V. Ossenkopf-Okada, R. Simon, J. P. Pérez-Beaupuits, H. Beuther, S. Bihr, R. Higgins, U. Graf та R. Güsten. "[C II] 158 μm self-absorption and optical depth effects". Astronomy & Astrophysics 636 (квітень 2020): A16. http://dx.doi.org/10.1051/0004-6361/201834380.
Повний текст джерелаАнотація:
Context. The [C II] 158 μm far-infrared fine-structure line is one of the most important cooling lines of the star-forming interstellar medium (ISM). It is used as a tracer of star formation efficiency in external galaxies and to study feedback effects in parental clouds. High spectral resolution observations have shown complex structures in the line profiles of the [C II] emission. Aims. Our aim is to determine whether the complex profiles observed in [12C II] are due to individual velocity components along the line-of-sight or to self-absorption based on a comparison of the [12C II] and isotopic [13C II] line profiles. Methods. Deep integrations with the SOFIA/upGREAT 7-pixel array receiver in the sources of M43, Horsehead PDR, Monoceros R2, and M17 SW allow for the detection of optically thin [13C II] emission lines, along with the [12C II] emission lines, with a high signal-to-noise ratio. We first derived the [12C II] optical depth and the [C II] column density from a single component model. However, the complex line profiles observed require a double layer model with an emitting background and an absorbing foreground. A multi-component velocity fit allows us to derive the physical conditions of the [C II] gas: column density and excitation temperature. Results. We find moderate to high [12C II] optical depths in all four sources and self-absorption of [12C II] in Mon R2 and M17 SW. The high column density of the warm background emission corresponds to an equivalent Av of up to 41 mag. The foreground absorption requires substantial column densities of cold and dense [C II] gas, with an equivalent Av ranging up to about 13 mag. Conclusions. The column density of the warm background material requires multiple photon-dominated region surfaces stacked along the line of sight and in velocity. The substantial column density of dense and cold foreground [C II] gas detected in absorption cannot be explained with any known scenario and we can only speculate on its origins.
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Peng, X., J. Zhu, L. He, W. Xiao, F. Luo, M. Xiao, and X. Wang. "Simulation study on optical transmission performance and time resolution of Shashlik tower." Journal of Instrumentation 18, no. 02 (February 1, 2023): P02018. http://dx.doi.org/10.1088/1748-0221/18/02/p02018.
Повний текст джерелаАнотація:
Abstract The Shashlik tower is a significant component to measure the energy, time, and position of photons and electrons in the Electromagnetic Calorimeter (ECal), a vital detector of the Multi-Purpose Detector (MPD) in the Nuclotron-based lon Collider fAcility (NICA), Dubna, Russia. Based on the GEANT4 simulation toolkit, a variation of physical behavior in the tower was simulated, including the changes of photons during transmission, and used the rising edge detection method to measure the time-resolving ability of the module for natural muons and electron beams. Results show that 3 GeV electrons enter the tower, photons emitted by the scintillator are transmitted, 10665 photoelectrons are collected on Silicon Multipliers (SiPMs), yield is 3555 pe/GeV, and the light output is 0.16%. The time resolution of the module for muons is better than 160 ps, but the value of each tower is different. In addition, by changing the electron beam energy in the simulation, we observed that a larger number of photoelectrons collected by SiPMs leads to a better time resolution. At an electron beam energy of 1 GeV, the time resolution of the tower could be better than 101 ps. The simulated measuring results, and the methods of the tower photon transmission performance and the time resolution, will provide references and new optimum methods for subsequent experiential tests.
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Sztucki, Michael, Manfred Burghammer, Oleg Konovalov, Edward Mitchell, and Theyencheri Narayanan. "Synchrotron X-ray Scattering techniques for soft matter industrial research and development." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1329. http://dx.doi.org/10.1107/s2053273314086707.
Повний текст джерелаАнотація:
Consumer products based on soft matter technology often exhibit macroscopic properties which are strongly dependent on their micro- and nano-structures extending over multiple size scales. Synchrotron scattering techniques are ideally suited for probing these multilevel structures and deliver complementary and in some cases unique information as compared to real space methods like confocal microscopy, cryo-electron microscopy or atomic force microscopy. The European Synchrotron Radiation Facility (ESRF) is a world-leading synchrotron light source which operates several state-of-the-art instruments for the investigation of soft materials and offers expertise to academic and industrial users. Fast and flexible access for proprietary experiments with a modular, fine-tuned service is guaranteed. A range of dedicated sample environments which mimic industrial processing conditions are available. This presentation will illustrate the state-of-the-art performance of the following synchrotron scattering techniques by recent examples of industrial relevance. Simultaneous small and wide angle X-ray scattering (SAXS/WAXS) is a powerful method to determine the microstructure and phase behavior of multi-component systems like detergents, food products, pharmaceutical components, polymer composites, etc. The high photon flux translates to high throughput measurements, while the high degree of collimation and resolution permit to elucidate a wide range of length scales from a few Angstroms up to micron scale. Scanning microbeam SAXS/WAXS and single micro-crystal/fiber diffraction (µXRD) allows elucidating the local nanostructure of very small objects like micro-specimens of composite organic/inorganic materials, teeth, bones, micromechanical parts, polymer fibers, micro fluidics, etc. with micro/nanometric real space resolution. X-ray reflectivity (XR) and grazing incidence diffraction/scattering (GID /GISAXS) can reveal the nanoscale structure and complexity of nano-structured complex fluids at interfaces, organic films, biological membranes, etc.
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Esposito, P., A. De Luca, R. Turolla, F. Coti Zelati, W. Hummel, A. Tiengo, G. L. Israel, N. Rea, R. P. Mignani, and A. Borghese. "Long X-ray flares from the central source in RCW 103." Astronomy & Astrophysics 626 (June 2019): A19. http://dx.doi.org/10.1051/0004-6361/201935412.
Повний текст джерелаАнотація:
We observed the slowly revolving pulsar 1E 161348–5055 (1E 1613, spin period of 6.67 h) in the supernova remnant RCW 103 twice with XMM-Newton and once with the Very Large Telescope (VLT). The VLT observation was performed on 2016 June 30, about a week after the detection of a large outburst from 1E 1613. At the position of 1E 1613, we found a near-infrared source with Ks = 20.68 ± 0.12 mag that was not detected (Ks > 21.2 mag) in data collected with the same instruments in 2006, during X-ray quiescence. Its position and behavior are consistent with a counterpart in the literature that was discovered with the Hubble Space Telescope in the following weeks in adjacent near-IR bands. The XMM-Newton pointings were carried out on 2016 August 19 and on 2018 February 14. While the collected spectra are similar in shape between each other and to what is observed in quiescence (a blackbody with kT ∼ 0.5 keV plus a second, harder component, either another hotter blackbody with kT ∼ 1.2 keV or a power law with photon index Γ ∼ 3), the two pointings caught 1E 1613 at different luminosity throughout its decay pattern: about 4.8 × 1034 erg s−1 in 2016 and 1.2 × 1034 erg s−1 in 2018 (0.5–10 keV, for the double-blackbody model and for 3.3 kpc), which is still almost about ten times brighter than the quiescent level. The pulse profile displayed dramatic changes, apparently evolving from the complex multi-peak morphology observed in high-luminosity states to the more sinusoidal form characteristic of latency. The inspection of the X-ray light curves revealed two flares with unusual properties in the 2016 observation: they are long (∼1 ks to be compared with 0.1–1 s of typical magnetar bursts) and faint (≈1034 erg s−1, with respect to 1038 erg s−1 or more in magnetars). Their spectra are comparatively soft and resemble the hotter thermal component of the persistent emission. If the flares and the latter component have a common origin, this may be a spot on the star surface that is heated by back-flowing currents that are induced by a magnetospheric twist. In this hypothesis, since the increase in luminosity of 1E 1613 during the flare is only ∼20%, an irregular variation of the same order in the twist angle could account for it.
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Lamont, Andrew C., Michael A. Restaino, Matthew J. Kim, and Ryan D. Sochol. "A facile multi-material direct laser writing strategy." Lab on a Chip 19, no. 14 (2019): 2340–45. http://dx.doi.org/10.1039/c9lc00398c.
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Avula, Leela Rani, Tiane Chen, Olga Kovbasnjuk, and Mark Donowitz. "Both NHERF3 and NHERF2 are necessary for multiple aspects of acute regulation of NHE3 by elevated Ca2+, cGMP, and lysophosphatidic acid." American Journal of Physiology-Gastrointestinal and Liver Physiology 314, no. 1 (January 1, 2018): G81—G90. http://dx.doi.org/10.1152/ajpgi.00140.2017.
Повний текст джерелаАнотація:
The intestinal epithelial brush border Na+/H+ exchanger NHE3 accounts for a large component of intestinal Na absorption. NHE3 is regulated during digestion by signaling complexes on its COOH terminus that include the four multi-PDZ domain-containing NHERF family proteins. All bind to NHE3 and take part in different aspects of NHE3 regulation. Because the roles of each NHERF appear to vary on the basis of the cell model or intestinal segment studied and because of our recent finding that a NHERF3-NHERF2 heterodimer appears important for NHE3 regulation in Caco-2 cells, we examined the role of NHERF3 and NHERF2 in C57BL/6 mouse jejunum using homozygous NHERF2 and NHERF3 knockout mice. NHE3 activity was determined with two-photon microscopy and the dual-emission pH-sensitive dye SNARF-4F. The jejunal apical membrane of NHERF3-null mice appeared similar to wild-type (WT) mice in surface area, microvillus number, and height, which is similar to results previously reported for jejunum of NHERF2-null mice. NHE3 basal activity was not different from WT in either NHERF2- or NHERF3-null jejunum, while d-glucose-stimulated NHE3 activity was reduced in NHERF2, but similar to WT in NHERF3 KO. LPA stimulation and UTP (elevated Ca2+) and cGMP inhibition of NHE3 were markedly reduced in both NHERF2- and NHERF3-null jejunum. Forskolin inhibited NHE3 in NHERF3-null jejunum, but the extent of inhibition was reduced compared with WT. The forskolin inhibition of NHE3 in NHERF2-null mice was too inconsistent to determine whether there was an effect and whether it was altered compared with the WT response. These results demonstrate similar requirement for NHERF2 and NHERF3 in mouse jejunal NHE3 regulation by LPA, Ca2+, and cGMP. The explanation for the similarity is not known but is consistent with involvement of a brush-border NHERF3-NHERF2 heterodimer or sequential NHERF-dependent effects in these aspects of NHE3 regulation. NEW & NOTEWORTHY NHERF2 and NHERF3 are apical membrane multi-PDZ domain-containing proteins that are involved in regulation of intestinal NHE3. This study demonstrates that NHERF2 and NHERF3 have overlapping roles in NHE3 stimulation by LPA and inhibition by elevated Ca2+ and cGMP. These results are consistent with their role being as a NHERF3-NHERF2 heterodimer or via sequential NHERF-dependent signaling steps, and they begin to clarify a role for multiple NHERF proteins in NHE3 regulation.
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Murao, Reiko, and Masao Kimura. "In situ observation of reduction reaction of calcium ferrites by XRD and XAFS." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1780. http://dx.doi.org/10.1107/s2053273314082199.
Повний текст джерелаАнотація:
The lime-fluxed iron ore sinter is the major iron source in the steelmaking process. Its macroscopic properties, (e.g. strength, reduction-ability and reduction-disintegration) should strongly depend on characteristics, quantity and morphology of the bonding phase. It contains several calcium ferrite phases (CFs) including solid solutions of gang materials. Most of previous studies focused on the relation of micro-texture with properties of the sinter. However, properties of individual CFs, especially, of multi-component CFs have not been clarified yet. In this study, reduction process and rates of various CFs have been investigated by in situ observation using both X-Ray Absorption Fine Structure (XAFS) and X-Ray Diffraction (XRD) methods to clarify influence of CF species on the properties of the sinter. High temperature XAFS measurements were carried out using a synchrotron radiation source at the 9A beam line in Photon Factory (KEK-PF), Japan. Powdered single phase CFs, such as CaFe2O4, Ca2(Fe,Ca)6(Fe,Al,Si)6O20 (SFCA) were diluted with BN. Fe K and Ca K-edge XAFS spectra at 9000C and 7500C in He-H2 gas atmosphere were collected repeatedly by the quick-XAFS method. Absorption variations in normalized XANES spectra were used to calculate the reduction rate constants[1]. XRD patterns of various CFs at 9000C and 7500C were corrected repeatedly at 40-second intervals in N2-H2 gas atmosphere during reduction reaction progressed. Reduction rate of CaFe2O4, determined by XANES analysis was slower than that of Fe2O3. The reduction of Fe in CaFe2O4 was a single first-order reaction, although an induction period was clearly observed at the beginning of the reduction process. In situ XRD observations showed that CaFe2O4 was reduced into Fe and CaO via Fe2+ containing CFs such as CaFe3O5 and CaFe5O7 at 9000C. These may correspond to the induction period observed in the absorption variation. Analysis results for SFCA will be discussed in the presentation.
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Malak, Henryk. "Up-Conversion and Two-Photon Excitation Fluorescence Properties of Phloxine B." Microscopy and Microanalysis 5, S2 (August 1999): 500–501. http://dx.doi.org/10.1017/s1431927600015828.
Повний текст джерелаАнотація:
A dye, Phloxine B, a common food coloring and one of the active components of a photoreactive insecticide was recently approved by Food and Drug Administration as D&C Red #28 for use in drugs and cosmetics. Phloxine B is also one of the most widely use stain in fluorescence microscopy. However, in spite of the widespread interest in multi-photon spectroscopy and imaging, no information is available on the electronic transitions properties of Phloxine B with red edge fluorescence excitation and with multi-photon excitation.In the present report we described the steady state and time-resolved fluorescent properties of Phloxine B with up-convert photon excitation and with two-photon excitation. We examined the electronic transitions properties of Phloxine B when was excited by femtosecond pulses from a mode-locked titanium sapphire laser or a mode-locked optical parametric oscillator laser. Phloxine B under excitation wavelengths above 775 nm was found to display two-photon excitation fluorescence with a spectrum maximum at 580 nm, which emission is consistent with one-photon excitation fluorescence spectrum. At the red edge excitation of Phloxine B, from 590 nm to 650 nm, we observed one-photon excitation fluorescence indicating that Phloxine B behaves like upconverting dye with one-photon excitation process.
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Zhao, Peng-Wei, and Qing-Wen Tang. "A Comprehensive Study of Bright Fermi-GBM Short Gamma-ray Bursts: I. Multi-Pulse Lightcurves and Multi-Component Spectra." Universe 8, no. 3 (March 2, 2022): 159. http://dx.doi.org/10.3390/universe8030159.
Повний текст джерелаАнотація:
Sorted by the photon fluences of short Gamma-ray Bursts (SGRBs) detected by the Fermi-Gamma Ray Burst Monitor (GBM), nine brightest bursts are selected to perform a comprehensive analysis. All GRB lightcurves are fitted well by 1 to 3 pulses that are modelled by fast-rising exponential decay profile (FRED), within which the resultant rising time is strongly positive-correlated with the full time width at half maxima (FWHM). A photon spectral model involving a cutoff power-law function and a standard blackbody function (CPL + BB) could reproduce the spectral energy distributions of these SGRBs well in the bursting phase. The CPL’s peak energy is found strongly positive-correlated with the BB’s temperature, which indicates they might be from the same physical origin. Possible physical origins are discussed to account for these correlations.
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Homma, Kensuke, Yuri Kirita, and Fumiya Ishibashi. "Perspective of Direct Search for Dark Components in the Universe with Multi-Wavelengths Stimulated Resonant Photon-Photon Colliders." Universe 7, no. 12 (December 6, 2021): 479. http://dx.doi.org/10.3390/universe7120479.
Повний текст джерелаАнотація:
We explore a possibility to detect dark components in the Universe via stimulated photon–photon collisions by focusing two-frequency coherent electromagnetic fields in a vacuum. Those fields are assumed to be pulsed reaching Fourier transform limits in near-infrared, THz, and GHz frequency bands, respectively. The numbers of signal photons as a result of exchange of a pseudoscalar-type pseudo Nambu–Goldstone boson have been evaluated in the individual frequency bands. Within presently available beam intensities, we found that the QCD axion scenarios are thoroughly testable in the mass range 10−6–100 eV based on the common method. Furthermore, we show a possibility to reach the weak coupling domain even beyond the gravitationally weak coupling strength if pulse compression in the GHz band is realized in the near future development.
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Sekatski, Pavel, Enky Oudot, Patrik Caspar, Rob Thew, and Nicolas Sangouard. "Benchmarking single-photon sources from an auto-correlation measurement." Quantum 6 (December 13, 2022): 875. http://dx.doi.org/10.22331/q-2022-12-13-875.
Повний текст джерелаАнотація:
Here we argue that the probability that a given source produces exactly a single photon is a natural quantity to benchmark single-photon sources as it certifies the absence of multi-photon components and quantifies the efficiency simultaneously. Moreover, this probability can be bounded simply from an auto-correlation measurement — a balanced beam splitter and two photon detectors. Such a bound gives access to various non-classicality witnesses that can be used to certify and quantify Wigner-negativity, in addition to non-Gaussianity and P-negativity of the state produced by the source. We provide tools that can be used in practice to account for an imperfect beam splitter, non-identical and non-unit detection efficiencies, dark counts and other imperfections, take finite statistical effects into account without assuming that identical states are produced in all rounds, and optionally allow one to remove the detector inefficiencies from the analysis. We demonstrate the use of the proposed benchmark, non-classicality witness and measure using a heralded single-photon source based on spontaneous parametric down-conversion. We report on an average probability that a single photon is produced ≥55% and an average measure of the Wigner negativity ≥0.004 with a confidence level of 1−10−10.
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Guetta, Dafne, Yael Hillman, and Massimo Della Valle. "Nova neutrinos in the multi-messenger era." Journal of Cosmology and Astroparticle Physics 2023, no. 03 (March 1, 2023): 015. http://dx.doi.org/10.1088/1475-7516/2023/03/015.
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Abstract The recently discovered high energy emission from the recurrent nova RS Ophiuchi by Fermi-LAT (> 100 MeV), H.E.S.S. and MAGIC (>100 GeV), hints towards a possible hadronic origin of this radiation component. From the observed high energy photon flux we derive the expected number of neutrino events that could be detected by present and future neutrino telescopes in the different energy ranges. Preliminary estimates indicate that with the “next-generation” instrument IceCube-Gen2, the expected number of neutrino detections from Galactic novae, admittedly with large uncertainty, should not exceed 1 event per decade.
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Dudak, J., and J. Zemlicka. "Multi bin energy-sensitive micro-CT using large area photon-counting detectors Timepix." Journal of Instrumentation 17, no. 01 (January 1, 2022): C01028. http://dx.doi.org/10.1088/1748-0221/17/01/c01028.
Повний текст джерелаАнотація:
Abstract X-ray micro-CT has become a popular and widely used tool for the purposes of scientific research. Although the current state-of-the-art micro-CT is on a high technology level, it still has some known limitations. One of the relevant issues is an inability to clearly identify and quantify specific materials. The mentioned drawback can be solved by the energy-sensitive CT approach. Dual-energy CT, which is already frequently used in human medicine, offers the identification of two different materials; for example, it differentiates an intravenous contrast agent from bone or it can indicate the composition of urinary stones. Resolving a larger number of material components within a single object is beyond the capabilities of dual-energy CT. Such an approach requires a higher number of measurements using different photon energies. A possible solution for multi bin, or so-called spectral CT, is the application of photon-counting detectors. Photon counting technology offers an integrated circuitry capable of resolving the energy of incoming photons in each pixel. Therefore, it is possible to collect data in user-defined energy windows. This contribution evaluates the applicability of the large-area photon-counting detector Timepix for multi bin energy-sensitive micro-CT. It presents an experimental phantom study focused on the simultaneous K-edge-based identification and quantification of multiple contrast agents within a single object. The paper describes the collection of multiple energy bins using the Timepix detector operated in the photon counting mode, explains the data processing, and demonstrates the results obtained from an in-house implemented basis material decomposition algorithm.
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Golvari, Pooria, and Stephen M. Kuebler. "Fabrication of Functional Microdevices in SU-8 by Multi-Photon Lithography." Micromachines 12, no. 5 (April 21, 2021): 472. http://dx.doi.org/10.3390/mi12050472.
Повний текст джерелаАнотація:
This review surveys advances in the fabrication of functional microdevices by multi-photon lithography (MPL) using the SU-8 material system. Microdevices created by MPL in SU-8 have been key to progress in the fields of micro-fluidics, micro-electromechanical systems (MEMS), micro-robotics, and photonics. The review discusses components, properties, and processing of SU-8 within the context of MPL. Emphasis is focused on advances within the last five years, but the discussion also includes relevant developments outside this period in MPL and the processing of SU-8. Novel methods for improving resolution of MPL using SU-8 and discussed, along with methods for functionalizing structures after fabrication.
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Sciara, Stefania, Piotr Roztocki, Bennet Fischer, Christian Reimer, Luis Romero Cortés, William J. Munro, David J. Moss, et al. "Scalable and effective multi-level entangled photon states: a promising tool to boost quantum technologies." Nanophotonics 10, no. 18 (November 9, 2021): 4447–65. http://dx.doi.org/10.1515/nanoph-2021-0510.
Повний текст джерелаАнотація:
Abstract Multi-level (qudit) entangled photon states are a key resource for both fundamental physics and advanced applied science, as they can significantly boost the capabilities of novel technologies such as quantum communications, cryptography, sensing, metrology, and computing. The benefits of using photons for advanced applications draw on their unique properties: photons can propagate over long distances while preserving state coherence, and they possess multiple degrees of freedom (such as time and frequency) that allow scalable access to higher dimensional state encoding, all while maintaining low platform footprint and complexity. In the context of out-of-lab use, photon generation and processing through integrated devices and off-the-shelf components are in high demand. Similarly, multi-level entanglement detection must be experimentally practical, i.e., ideally requiring feasible single-qudit projections and high noise tolerance. Here, we focus on multi-level optical Bell and cluster states as a critical resource for quantum technologies, as well as on universal witness operators for their feasible detection and entanglement characterization. Time- and frequency-entangled states are the main platform considered in this context. We review a promising approach for the scalable, cost-effective generation and processing of these states by using integrated quantum frequency combs and fiber-based devices, respectively. We finally report an experimentally practical entanglement identification and characterization technique based on witness operators that is valid for any complex photon state and provides a good compromise between experimental feasibility and noise robustness. The results reported here can pave the way toward boosting the implementation of quantum technologies in integrated and widely accessible photonic platforms.
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Wang, Xuan, Liju Yin, Mingliang Gao, Zhenzhou Wang, Jin Shen, and Guofeng Zou. "Denoising Method for Passive Photon Counting Images Based on Block-Matching 3D Filter and Non-Subsampled Contourlet Transform." Sensors 19, no. 11 (May 29, 2019): 2462. http://dx.doi.org/10.3390/s19112462.
Повний текст джерелаАнотація:
Multi-pixel photon counting detectors can produce images in low-light environments based on passive photon counting technology. However, the resulting images suffer from problems such as low contrast, low brightness, and some unknown noise distribution. To achieve a better visual effect, this paper describes a denoising and enhancement method based on a block-matching 3D filter and a non-subsampled contourlet transform (NSCT). First, the NSCT was applied to the original image and histogram-equalized image to obtain the sub-band low- and high-frequency coefficients. Regional energy and scale correlation rules were used to determine the respective coefficients. Adaptive single-scale retinex enhancement was applied to the low-frequency components to improve the image quality. The high-frequency sub-bands whose line features were best preserved were selected and processed using a symbol function and the Bayes-shrink threshold. After applying the inverse transform, the fused photon counting image was subjected to an improved block-matching 3D filter, significantly reducing the operation time. The final result from the proposed method was superior to those of comparative methods in terms of several objective evaluation indices and exhibited good visual effects and details from the objective impression.
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Franzen, Jochen, Rüdiger Frey, and Holger Nagel. "Fast monitoring of motor exhaust components by resonant multi-photon ionisation and time-of-flight mass spectrometry." Journal of Molecular Structure 347 (March 1995): 143–51. http://dx.doi.org/10.1016/0022-2860(95)08542-4.
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Henkel, C., K. M. Menten, J. Braatz, R. Mauersberger, A. Weiß, M. Lebrón, A. Tarchi, A. B. Peck, C. L. Carilli, and D. A. Lubowich. "Extragalactic Ammonia." Highlights of Astronomy 13 (2005): 879–81. http://dx.doi.org/10.1017/s1539299600017391.
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AbstractMulti-line data of ammonia (NH3) are presented for Maffei 2, IC 342, and the starburst galaxies NGC 253 and M 82. While in M 82 the NH3 emitting gas is cool, presumably arising from well shielded dense cores deeply embedded in an environment dominated by Photon Dominated Regions, the other galaxies show ‘warm’ and ‘hot’ components that may be heated by shocks, ion-slip or cosmic rays. Interferometric observations show the detailed large scale distribution of NH3 in galaxies for the first time. The first multi-line studies of ammonia at significant redshifts (z = 0.65 and 0.89) are also reported and rotational temperatures, measures of the kinetic temperature of the emitting gas, are derived for all sources.
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Chkareuli, J. L., and Z. Kepuladze. "Emergent Yang–Mills theories from universal extra dimensions." Modern Physics Letters A 32, no. 05 (February 7, 2017): 1750029. http://dx.doi.org/10.1142/s0217732317500298.
Повний текст джерелаАнотація:
We study emergent Yang–Mills theories which could origin from universal extra dimensions. Particularly, some vector field potential terms or polynomial vector field constraints introduced into five-dimensional (5D) non-Abelian gauge theory is shown to lead to spontaneous violation of an underlying spacetime symmetry and generate vector pseudo-Goldstone modes as conventional four-dimensional (4D) gauge boson candidates. As a special signature, apart from conventional gauge couplings, there appear an infinite number of the properly suppressed direct multi-boson (multi-photon in particular) interaction couplings in emergent Yang–Mills theories whose observation could shed light on their high-dimensional nature. Moreover, in these theories, an internal symmetry also appeared spontaneously broken to its diagonal subgroups. This breaking originates from the extra vector field components playing the role of some adjoint scalar field multiplet in the 4D spacetime. So, one naturally has the Higgs effect without a specially introduced scalar field multiplet. Remarkably, when applied to Grand Unified Theories (GUTs), this results in an automatic breakdown of emergent GUTs down to the Standard Model (SM) just at the 5D Lorentz violation scale M.
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Kellermann, G., F. Vicentin, E. Tamura, M. Rocha, H. Tolentino, A. Barbosa, A. Craievich, and I. Torriani. "The Small-Angle X-ray Scattering Beamline of the Brazilian Synchrotron Light Laboratory." Journal of Applied Crystallography 30, no. 5 (October 1, 1997): 880–83. http://dx.doi.org/10.1107/s0021889897001829.
Повний текст джерелаАнотація:
This paper describes the small-angle scattering beamline built at the Brazilian Synchrotron Light Laboratory (LNLS). Vertical focusing of the synchrotron beam is achieved by an elastically bent gold-plated cylindrical mirror. An asymmetric cut curved triangle-shaped silicon single crystal (111 reflection) is used for monochromatization and horizontal focusing. The mirror, monochromator optics and 2θ arm were designed to cover the spectral range between 1.0 and 2.0 Å. Three slit sets, a secondary photon shutter, two beam monitors, filters and absorbers, a multi-sample holder, a vacuum path, a beam-stopper and a set of detectors are the basic components of the workstation. The stepping motors are equipped with specially designed encoders. All mechanical and pneumatic movements and detectors can be remotely controlled using a direct panel or a PC.
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Hammarström, Leif, and Stenbjörn Styring. "Coupled electron transfers in artificial photosynthesis." Philosophical Transactions of the Royal Society B: Biological Sciences 363, no. 1494 (October 18, 2007): 1283–91. http://dx.doi.org/10.1098/rstb.2007.2225.
Повний текст джерелаАнотація:
Light-induced charge separation in molecular assemblies has been widely investigated in the context of artificial photosynthesis. Important progress has been made in the fundamental understanding of electron and energy transfer and in stabilizing charge separation by multi-step electron transfer. In the Swedish Consortium for Artificial Photosynthesis, we build on principles from the natural enzyme photosystem II and Fe-hydrogenases. An important theme in this biomimetic effort is that of coupled electron-transfer reactions, which have so far received only little attention. (i) Each absorbed photon leads to charge separation on a single-electron level only, while catalytic water splitting and hydrogen production are multi-electron processes; thus there is the need for controlling accumulative electron transfer on molecular components. (ii) Water splitting and proton reduction at the potential catalysts necessarily require the management of proton release and/or uptake. Far from being just a stoichiometric requirement, this controls the electron transfer processes by proton-coupled electron transfer (PCET). (iii) Redox-active links between the photosensitizers and the catalysts are required to rectify the accumulative electron-transfer reactions, and will often be the starting points of PCET.
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Chiarelli, Antonio Maria, David Perpetuini, Pierpaolo Croce, Giuseppe Greco, Leonardo Mistretta, Raimondo Rizzo, Vincenzo Vinciguerra, et al. "Fiberless, Multi-Channel fNIRS-EEG System Based on Silicon Photomultipliers: Towards Sensitive and Ecological Mapping of Brain Activity and Neurovascular Coupling." Sensors 20, no. 10 (May 16, 2020): 2831. http://dx.doi.org/10.3390/s20102831.
Повний текст джерелаАнотація:
Portable neuroimaging technologies can be employed for long-term monitoring of neurophysiological and neuropathological states. Functional Near-Infrared Spectroscopy (fNIRS) and Electroencephalography (EEG) are highly suited for such a purpose. Their multimodal integration allows the evaluation of hemodynamic and electrical brain activity together with neurovascular coupling. An innovative fNIRS-EEG system is here presented. The system integrated a novel continuous-wave fNIRS component and a modified commercial EEG device. fNIRS probing relied on fiberless technology based on light emitting diodes and silicon photomultipliers (SiPMs). SiPMs are sensitive semiconductor detectors, whose large detection area maximizes photon harvesting from the scalp and overcomes limitations of fiberless technology. To optimize the signal-to-noise ratio and avoid fNIRS-EEG interference, a digital lock-in was implemented for fNIRS signal acquisition. A benchtop characterization of the fNIRS component showed its high performances with a noise equivalent power below 1 pW. Moreover, the fNIRS-EEG device was tested in vivo during tasks stimulating visual, motor and pre-frontal cortices. Finally, the capabilities to perform ecological recordings were assessed in clinical settings on one Alzheimer’s Disease patient during long-lasting cognitive tests. The system can pave the way to portable technologies for accurate evaluation of multimodal brain activity, allowing their extensive employment in ecological environments and clinical practice.
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Zhang, Fan, Andrew J. Allen, Lyle E. Levine, Derrick C. Mancini, and Jan Ilavsky. "Simultaneous multiplexed materials characterization using a high-precision hard X-ray micro-slit array." Journal of Synchrotron Radiation 22, no. 3 (April 22, 2015): 653–60. http://dx.doi.org/10.1107/s1600577515005378.
Повний текст джерелаАнотація:
The needs both for increased experimental throughput and forin operandocharacterization of functional materials under increasingly realistic experimental conditions have emerged as major challenges across the whole of crystallography. A novel measurement scheme that allows multiplexed simultaneous measurements from multiple nearby sample volumes is presented. This new approach enables better measurement statistics or direct probing of heterogeneous structure, dynamics or elemental composition. To illustrate, the submicrometer precision that optical lithography provides has been exploited to create a multiplexed form of ultra-small-angle scattering based X-ray photon correlation spectroscopy (USAXS-XPCS) using micro-slit arrays fabricated by photolithography. Multiplexed USAXS-XPCS is applied to follow the equilibrium dynamics of a simple colloidal suspension. While the dependence of the relaxation time on momentum transfer, and its relationship with the diffusion constant and the static structure factor, follow previous findings, this measurements-in-parallel approach reduces the statistical uncertainties of this photon-starved technique to below those associated with the instrument resolution. More importantly, we note the potential of the multiplexed scheme to elucidate the response of different components of a heterogeneous sample underidenticalexperimental conditions insimultaneousmeasurements. In the context of the X-ray synchrotron community, this scheme is, in principle, applicable to all in-line synchrotron techniques. Indeed, it has the potential to open a new paradigm forin operandocharacterization of heterogeneous functional materials, a situation that will be even further enhanced by the ongoing development of multi-bend achromat storage ring designs as the next evolution of large-scale X-ray synchrotron facilities around the world.
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Lavin, C. A., W. A. Mohler, H. H. Keating, and J. G. White. "Capturing Developmental Events of the C. Elegans Embryo by High Pressure Freezing After Monitoring by a Multi-Photon Imaging System." Microscopy and Microanalysis 3, S2 (August 1997): 291–92. http://dx.doi.org/10.1017/s1431927600008345.
Повний текст джерелаАнотація:
High pressure freezing enables the rapid arrest of developmental events without prefixation. Standard chemical fixation is a time dependent event and may cause artifacts in sensitive cytoskeletal components. We are studying two developmental events in embryonic Caenorhabditis elegans: that involve changes in the cytoskeleton: spindle alignment and membrane fusion. The mitotic spindle undergoes rapid rotational alignment prior to certain differentiative divisions. We are trying to capture these events by anticipation their timing and rapid freezing. Precursor hypodermal cells of embryonic C. elegans undergo a transition from individual cells to a syncytium at the onset of morphogenesis. In an effort to visualize the fusion events, embryos were stained with the vital probe FM4-64 to highlight cell membranes. Development was monitored by fluorescent microscopy using multiple-photon excitation imaging to minimize photobleaching while providing clear images of deep sections. Small cellulose capillary tubes, as described by Hohenberg for isolation and high pressure freezing of individual cells, were not of sufficient optical quality for monitoring by a laser-scanning microscope.
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Peng, X., K. Zhu, X. Ji, M. Xiao, F. Luo, Y. Huang, J. Zhu, et al. "Simulation study on photon generation and collection of tower applied to NICA-MPD electromagnetic calorimeter." Journal of Instrumentation 17, no. 01 (January 1, 2022): T01004. http://dx.doi.org/10.1088/1748-0221/17/01/t01004.
Повний текст джерелаАнотація:
Abstract Shashlik tower, which is composed of absorbers and scintillators alternately, surrounded by reflector and coupled with Silicon Photomultiplier (SiPM) by Wavelength-Shifting (WLS) fibers, is a significant component to measure the energy and position of photons and electrons in Electromagnetic Calorimeter (ECal), a key detector of the Multi Purpose Detector (MPD) at the Nuclotron-based Ion Collider facility (NICA) in Russia. In this paper, the effect of materials adopted for absorber, reflector and WLS fiber, the length and curvature of fibers and the electrons incident position on photons transmission performance of tower is simulated based on GEANT4 software. The impact of Gaussian deviation's electron beam energy and spread of 10% in the energy range on the energy resolution of tower is also studied. Results show that the low polishing degree absorber, the high polishing degree TiO_2 reflector and the type of Y-11 WLS fibers bent with a curvature radius of greater than 11 cm can significantly improve the light output. In addition, electrons injected along the centre of tower can make photons position distribution in SiPM more uniform. The generation time of photons in scintillators and time of arrival at the SiPM both obey the Landau distribution. Finally, the energy resolution of tower can be better than 3.8%/√(E) (GeV) for a Gaussian deviation's electron beam with an average energy of 3 GeV and spread of 10% in the energy range.
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Nigro, C., J. Sitarek, P. Gliwny, D. Sanchez, A. Tramacere, and M. Craig. "agnpy: An open-source python package modelling the radiative processes of jetted active galactic nuclei." Astronomy & Astrophysics 660 (April 2022): A18. http://dx.doi.org/10.1051/0004-6361/202142000.
Повний текст джерелаАнотація:
Context. Modelling the broadband emission of jetted active galactic nuclei (AGN) constitutes one of the main research topics of extragalactic astrophysics in the multi-wavelength and multi-messenger domain. Aims. We present agnpy, an open-source python package modelling the radiative processes of relativistic particles accelerated in the jets of AGN. The package includes classes describing the galaxy components responsible for line and thermal emission and it calculates the absorption due to γγ pair production on several photon fields. agnpy aims to extend the effort of modelling and interpreting the emission of extragalactic sources to a wide number of astrophysicists. Methods. We present the package content and illustrate a few examples of applications of its functionalities. We validate the software by comparing its results against the literature and against other open-source software. Results. We illustrate the utility of agnpy in addressing the most common questions encountered while modelling the emission of jetted active galaxies. When comparing its results against the literature and other modelling tools adopting the same physical assumptions, we achieve an agreement within 10 − 30%. Conclusions. agnpy represents one of the first systematic and validated collection of established radiative processes for jetted active galaxies in an open-source python package. We hope it will also stand among the first endeavours providing reproducible and transparent astrophysical software not only for data reduction and analysis, but also for modelling and interpretation.
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Yamasaki, Shotaro, Kazumi Kashiyama, and Kohta Murase. "Multi-wavelength constraints on the outflow properties of the extremely bright millisecond radio bursts from the galactic magnetar SGR 1935 + 2154." Monthly Notices of the Royal Astronomical Society 511, no. 3 (February 2, 2022): 3138–49. http://dx.doi.org/10.1093/mnras/stac234.
Повний текст джерелаАнотація:
ABSTRACT Extremely bright coherent radio bursts with millisecond duration, reminiscent of cosmological fast radio bursts, were codetected with anomalously-hard X-ray bursts from a Galactic magnetar SGR 1935 + 2154. We investigate the possibility that the event was triggered by the magnetic energy injection inside the magnetosphere, thereby producing magnetically-trapped fireball (FB) and relativistic outflows simultaneously. The thermal component of the X-ray burst is consistent with a trapped FB with an average temperature of ∼200–300 keV and size of ∼105 cm. Meanwhile, the non-thermal component of the X-ray burst and the coherent radio burst may arise from relativistic outflows. We calculate the dynamical evolution of the outflow, launched with an energy budget of 1039–1040 erg comparable to that for the trapped FB, for different initial baryon load η and magnetization σ0. If hard X-ray and radio bursts are both produced by the energy dissipation of the outflow, the outflow properties are constrained by combining the conditions for photon escape and the intrinsic timing offset ≲ 10 ms among radio and X-ray burst spikes. We show that the hard X-ray burst must be generated at rX ≳ 108 cm from the magnetar, irrespective of the emission mechanism. Moreover, we find that the outflow quickly accelerates up to a Lorentz factor of 102 ≲ Γ ≲ 103 by the time it reaches the edge of the magnetosphere and the dissipation occurs at 1012 cm ≲ rradio, X ≲ 1014 cm. Our results imply either extremely-clean (η ≳ 104) or highly-magnetized (σ0 ≳ 103) outflows, which might be consistent with the rarity of the phenomenon.
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Nachtmann, Marcel, Shaun Paul Keck, Frank Braun, Hanns Simon Eckhardt, Christoph Mattolat, Norbert Gretz, Stephan Scholl, and Matthias Rädle. "A customized stand-alone photometric Raman sensor applicable in explosive atmospheres: a proof-of-concept study." Journal of Sensors and Sensor Systems 7, no. 2 (October 12, 2018): 543–49. http://dx.doi.org/10.5194/jsss-7-543-2018.
Повний текст джерелаАнотація:
Abstract. This paper presents an explosion-proof two-channel Raman photometer designed for chemical process monitoring in hazardous explosive atmospheres. Due to its design, alignment of components is simplified and economic in comparison to spectrometer systems. Raman spectrometers have the potential of becoming an increasingly important tool in process analysis technologies as part of molecular-specific concentration monitoring. However, in addition to the required laser power, which restricts use in potentially explosive atmospheres, the financial hurdle is also high. Within the scope of a proof of concept, it is shown that photometric measurements of Raman scattering are possible. The use of highly sensitive detectors allows the required excitation power to be reduced to levels compliant for operation in potentially explosive atmospheres. The addition of an embedded platform enables stable use as a self-sufficient sensor, since it carries out all calculations internally. Multi-pixel photon counters (MPPCs) with large detection areas of 1350 µm2 are implemented as detectors. As a result, the sensitivity of the sensor is strongly increased. This gain in sensitivity is primarily achieved through two characteristics: first, the operating principle “avalanche breakdown” to detect single photons is used; second, the size of the image projected onto the MPPC is much bigger than the pixel area in competing Raman-Spectrometers resulting in higher photon flux. This combination enables reduction of the required excitation power to levels compliant for operation in potentially explosive atmospheres. All presented experiments are performed with strongly attenuated laser power of 35 mW. These include the monitoring of the analytes ethanol and hydrogen peroxide as well as the reversible binding of CO2 to amine. Accordingly, the described embedded sensor is ideally suited as a process analytical technology (PAT) tool for applications in environments with limitations on power input.
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Chien, Po-Jen, Takuma Suzuki, Ming Ye, Koji Toma, Takahiro Arakawa, Yasuhiko Iwasaki, and Kohji Mitsubayashi. "Ultra-Sensitive Isopropanol Biochemical Gas Sensor (Bio-Sniffer) for Monitoring of Human Volatiles." Sensors 20, no. 23 (November 29, 2020): 6827. http://dx.doi.org/10.3390/s20236827.
Повний текст джерелаАнотація:
Our groups have previously developed a biochemical gas sensor to measure isopropanol (IPA) in exhaled air and have applied it for breath IPA investigation in healthy subjects and diabetes patients. In this study, the original bio-sniffer was modified with a series of components that improved the limit of detection (LOD). First, the modified IPA bio-sniffer used a C8855-type photomultiplier tube (PMT) that performed well in the photon sensitivity at the peak wavelength of nicotinamide adenine dinucleotide (NADH) fluorescence. Second, the multi-core bifurcated optical fiber, which incorporated 36 fibers to replace the previous dual-core type, enhanced the fluorescence collection. Third, the optical fiber probe was reinforced for greater width, and the flow-cell was redesigned to increase the area of the enzyme-immobilized membrane in contact with the air sample. These modifications lowered the detection limit to 0.5 ppb, a significant increase over the previous 1.0 ppb. Moreover, the modified bio-sniffer successfully analyzed the IPA concentration in exhaled air from a volunteer, which confirmed its capability for real-world sample detection. The modified bio-sniffer is more applicable to breath measurement and the detection of other extremely-low-concentration samples.
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Benoit, Andres Gilberto Machado da Silva, and Adriano Petry. "Evaluation of F10.7, Sunspot Number and Photon Flux Data for Ionosphere TEC Modeling and Prediction Using Machine Learning Techniques." Atmosphere 12, no. 9 (September 16, 2021): 1202. http://dx.doi.org/10.3390/atmos12091202.
Повний текст джерелаАнотація:
Considering the growing volumes and varieties of ionosphere data, it is expected that automation of analytical model building using modern technologies could lead to more accurate results. In this work, machine learning techniques are applied to ionospheric modeling and prediction using sun activity data. We propose Total Electron Content (TEC) spectral analysis, using discrete cosine transform (DCT) to evaluate the relation to the solar features F10.7, sunspot number and photon flux data. The ionosphere modeling procedure presented is based on the assessment of a six-year period (2014–2019) of data. Different multi-dimension regression models were considered in experiments, where each geographic location was independently evaluated using its DCT frequency components. The features correlation analysis has shown that 5-year data seem more adequate for training, while learning curves revealed overfitting for polynomial regression from the 4th to 7th degrees. A qualitative evaluation using reconstructed TEC maps indicated that the 3rd degree polynomial regression also seems inadequate. For the remaining models, it can be noted that there is seasonal variation in root-mean-square error (RMSE) clearly related to the equinox (lower error) and solstice (higher error) periods, which points to possible seasonal adjustment in modeling. Elastic Net regularization was also used to reduce global RMSE values down to 2.80 TECU for linear regression.