Miracle-dz/UniFAR-FTUs huggingface dataset:
Beam splitting and Hong-Ou-Mandel interference for stored light

Storing and release of a quantum light pulse in a medium of atoms in the tripod configuration are studied. Each of these operations is realized by switching on and off two sets of properly chosen control fields. The system constitutes a kind of a flexible beam splitter in which the input and output ports concern photons of the same direction but well separated in time. A version of Hong-Ou-Mandel interference is discussed. It is also shown that a stored nonclassical light is split into two nonclassical beams, with their statistical properties being steered by a choice of the control fields.
Translational invariance and the space-time Lorentz transformation with arbitrary spatial coordinates

Translational invariance requires that physical predictions are independent of the choice of spatial coordinate system used. The time dilatation eﬀect of special relativity is shown to manifestly respect this invariance. Consideration of the space-time Lorentz transformation with arbitrary spatial coordinates shows that the spurious ‘length contraction’ and ‘relativity of simultaneity’ eﬀects —the latter violating translational invariance— result from the use of a diﬀerent spatial coordinate system to describe each of two spatially separated clocks at rest in a common inertial frame.
The earliest epoch of re-ionization in the standard Λ cold dark matter model

We show that the earliest possible re-ionization of the Universe is approximately at z ≃ 13.5 and the optical depth is τ ≃ 0.17 in the conventionally accepted A cold dark matter (ACDM) model with adiabatic fluctuations of a flat spectrum normalized to the cosmic microwave background. This is consistent with the re-ionization found by the Wilkinson Microwave Anisotropy Probe (WMAP) (the apparently earlier re-ionization epoch of the WMAP is ascribed to the adoption of the instantaneous re-ionization approximation), i.e. the WMAP result is realized only if re-ionization of the Universe takes place nearly at the maximal efficiency in the ACDM model.
A radial-velocity survey of Ap stars with HARPS - I. HD 42659: The discovery of the first spectroscopic binary around a rapidly oscillating Ap star

Context. Chemically peculiar Ap stars are main-sequence stars of spectral type B8–F3 which show large overabundances of some chemical elements (e.g., Si, Sr, Cr), especially of rare-earth elements, compared to normal A-type stars. Furthermore, they have strong, global magnetic fields and low rotational velocities. Some Ap stars exhibit high-overtone, low-degree, non-radial p-mode pulsations with periods of 6–24 min and are called rapidly oscillating Ap (roAp) stars. Interestingly, no roAp star is known to be a spectroscopic binary (SB), while many non-oscillating Ap (noAp) stars are found in SB systems. Aims. The goal of this survey was to carry out a systematic search for sub-stellar and stellar companions around Ap stars. Methods. Between 2004 and 2009, we observed 65 chemically peculiar stars with the HARPS spectrograph at the 3.6-m telescope at the European Southern Observatory (La Silla, Chile). The radial-velocity (RV) measurements were obtained using a new software called HARPS-TERRA which is based on a least-squares matching of each individual spectrum to a high signal-to-noise ratio template for each star. Results. We find significant variability with a period of 93.2 days and a semi-amplitude of 11.85 km s −1 in the RVs of HD 42659, a star of our sample that belongs to the group of roAp stars. This variability is caused by a stellar companion with a minimum mass of
X-Ray Energy Spectra of the Supersoft X-Ray Sources CAL 87 and RX J0925.7–4758 Observed with ASCA

We report observation results of the supersoft X-ray sources CAL 87 and RX J0925.7-4758 with the X-ray CCD cameras (Solid-State Imaging Spectrometers [SISs]) on board ASCA. Because of the superior energy resolution of the SIS (ΔE/E ~ 10% at 1 keV) relative to previous instruments, we could study detailed X-ray spectral structures of these sources for the first time. We have applied theoretical spectral models to CAL 87 and constrained the white dwarf mass and intrinsic luminosity as 0.8-1.2 M☉ and 4 × 1037-1.2 × 1038 ergs s-1, respectively. However, we have found the observed luminosity is an order of magnitude smaller than the theoretical estimate, which indicates that the white dwarf is permanently blocked by the accretion disk, and we are observing a scattering emission by a fully ionized accretion disk corona (ADC) whose column density is ~1.5 × 1023 cm-2. Through simulation we have shown that the orbital eclipse can be explained by the ADC model, such that a part of the extended X-ray emission from the ADC is blocked by the companion star filling its Roche lobe. We have found that very high surface gravity and temperature, ~1010 cm s-2 and ~100 eV, respectively, as well as a strong absorption edge at ~1.02 keV, are required to explain the X-ray energy spectrum of RX J0925.7-4758. These values are only possible for an extremely heavy white dwarf near the Chandrasekhar limit. Although the supersoft source luminosity should be ~1038 ergs s-1 at the Chandrasekhar limit, the observed luminosity of RX J0925.7-4758 is nearly 2 orders of magnitude smaller, even assuming an extreme distance of ~10 kpc. To explain the luminosity discrepancy, we propose a model in which very thick matter that was previously ejected from the system, as a form of jets, intervenes the line of sight and reduces the luminosity significantly because of Thomson scattering.
Terahertz emission from metal nanoparticles due to ultrafast heating

We demonstrate theoretically that ultrafast heating of metal nanoparticles by the laser pulse should lead to the generation of coherent terahertz (THz) radiation during the heat redistribution process. It is shown that after the femtosecond laser pulse action the time-dependent gradient of the electronic temperature induces low-frequency particle polarization with the characteristic timescale of about fractions of picosecond. In the case of the directed metallic pattern, the THz pulse waveform can be controlled by changing geometry of the individual particle. The generation mechanism proposed in this Letter can be used for interpretation of the recent experiments on the THz generation from metallic nanoparticles and nanostructures.
Negative permeability characterization of gyrotropic hexaferrite in the millimeter wave band for engineering of double-negative devices

Thin, square, hexaferrite plates, with magnetization normal to the broad faces, are investigated as fundamental components for creating metamaterials with double-negative character in the millimeter wave band. The intrinsic, chiral, magneto-optical properties of a newly discovered special hexaferrite ceramic (named FB6H), are characterized using a general-purpose, free-space, quasioptical, millimeter wave reflectometer that measures with high numerical and operational efficiency to high accuracy. The FB6H material proves itself to be amenable to possible adaption for delivery of low-loss, broadband double-negative devices and for more challenging reaches into the millimeter/submillimeter wave band due to its stable, broadband negative permeability and promising natural, low-loss properties.
A Very High Energy Gamma-Ray Spectrum of 1ES 2344+514

The BL Lacertae (BL Lac) object 1ES 2344+514 (1ES 2344), at a redshift of 0.044, was discovered as a source of very high energy (VHE) gamma rays by the Whipple collaboration in 1995 (Catanese et al.). This detection was recently confirmed by the HEGRA collaboration (Tluczykont et al.). As is typical for high-frequency-peaked blazars, the VHE gamma-ray emission is highly variable. On the night of 1995 December 20, a gamma-ray flare of 5.3 σ significance was detected, the brightest outburst from this object to date. The emission region is compatible with a point source. The spectrum between 0.8 and 12.6 TeV can be described by a power law, If we compare the spectral index with that of the other five confirmed TeV blazars, the spectrum of 1ES 2344 is similar to that of 1ES 1959+650, which is located at almost the same distance. The spectrum of 1ES 2344 is steeper than the brightest flare spectra of Markarian 421 (Mrk 421) and Markarian 501 (Mrk 501), both of which are located at a distance about two-thirds that of 1ES 2344, and harder than the spectra of PKS 2155-304 and H1426+428, which are located almost 3 times as far away. This trend is consistent with attenuation caused by the infrared extragalactic background radiation.
Imaging the dynamics of an individual hydrogen atom intercalated between two graphene sheets

The interlayer gallery between two adjacent sheets of van der Waals materials is expected to modify properties of atoms and molecules confined at the atomic interfaces. Here, we directly image individual hydrogen atom intercalated between two graphene sheets and investigate its dynamics by scanning tunnelling microscopy (STM). The intercalated hydrogen atom is found to be remarkably different from atomic hydrogen chemisorbed on the external surface of graphene. Our STM measurements, complemented by first-principles calculations, show that the hydrogen atom intercalated between two graphene sheets has dramatically reduced potential barriers for elementary migration steps. Especially, the confined atomic hydrogen dissociation energy from one of the graphene sheet is reduced to 0.34 eV, which is only about a third of a hydrogen atom chemisorbed on the external surface of graphene. This offers a unique platform for direct imaging of the atomic dynamics of confined atoms. Our results suggest that the atomic interfaces of van der Waals materials provide a confined environment to tune the dynamics process of confined atoms or molecules.
Reassessment of the Null Result of the HST Search for Planets in 47 Tucanae

We revisit the null result of the Hubble Space Telescope search for transiting planets in the globular cluster 47 Tucanae, in the light of improved knowledge of planet occurrence from the Kepler mission. Gilliland and co-workers expected to find 17 planets, assuming the 47 Tuc stars have close-in giant planets with the same characteristics and occurrence rates as those of the nearby stars that had been surveyed up until 1999. We update this result by assuming that 47 Tuc and Kepler stars have identical planet populations. The revised number of expected detections is . When we restrict the Kepler stars to the same range of masses as the stars that were searched in 47 Tuc, the number of expected detections is reduced to . Thus, the null result of the HST search is less statistically significant than it originally seemed. We cannot reject even the extreme hypothesis that 47 Tuc and Kepler stars have the same planet populations, with more than 2–3σ significance. More sensitive searches are needed to allow for comparisons between the planet populations of globular clusters and field stars.
Electrical characteristics and conduction mechanisms of metal-insulator-metal capacitors with nanolaminated Al2O3-HfO2 dielectrics

Electrical characteristics of metal-insulator-metal capacitors with various Al2O3–HfO2 nanolaminates are investigated. The results indicate that the breakdown field decreases with increasing the HfO2 individual-layer (IL) thickness. Concerning the same dielectric composition, the insulator with a thinner HfO2 IL also exhibits a significant improvement in the electrical breakdown and leakage characteristics. This is attributed to enhanced crystallization of the thicker HfO2 ILs. The insulator with alternate 1nm Al2O3 and 5nm HfO2 exhibits a breakdown field of 3.85MV∕cm at 125°C, and a leakage current of 9.6×10−8A∕cm2 at 1MV∕cm and 200°C. Further, it is revealed that the conduction mechanism in the high field range is dominated by the Poole–Frenkel emission with intrinsic trap energy of 1.91eV.
Hubble Space Telescope Observations of the Local Group Dwarf Galaxy Leo I

We present deep HST F555W (V) and F814W (I) observations of a central field in the Local Group dwarf spheroidal (dSph) galaxy Leo I. The resulting color-magnitude diagram (CMD) reaches I≃26 and reveals the oldest ≃10-15 Gyr old turnoffs. Nevertheless, a horizontal branch is not obvious in the CMD. Given the low metallicity of the galaxy, this likely indicates that the first substantial star formation in the galaxy may have been somehow delayed in Leo I in comparison with the other dSph satellites of the Milky Way. The subgiant region is well and uniformly populated from the oldest turnoffs up to the 1 Gyr old turnoff, indicating that star formation has proceeded in a continuous way, with possible variations in intensity but no big gaps between successive bursts, over the galaxy's lifetime. The structure of the red clump of core He-burning stars is consistent with the large amount of intermediate-age population inferred from the main sequence and the subgiant region. In spite of the lack of gas in Leo I, the CMD clearly shows star formation continuing until 1 Gyr ago and possibly until a few hundred Myr ago in the central part of the galaxy.
On the phase transition of KDP crystals: Comments on the interpretations of raman spectra

Abstract We reconfirm that the overdamped B 2 mode measured first by Kaminow and Damen, is the so-called soft mode responsible to the ferroelectric phase transition. It does not consist of two modes, narrow relaxational mode plus another non-ferroelectric mode, but a single mode which continuously gets narrower and stronger as T → Tc . In the ferroelectric phase, the central part of spectra is still the soft mode and the additional side peak near 140 cm−1 is not so. The soft mode of KDP type crystals far above Tc has oscillatory nature and crosses over to the relaxational motion in the vicinity of Tc . The temperature dependence of the soft mode is well explained by considering that the γ’ is proportional to |T - Tc |, where the γ’ is the characteristic frequency of the mode and is equal to |ω1| of the pole ω1 of the susceptibility χ(ω).
On the wave nature of matter: A transition from classical mechanics to quantum mechanics

Following the spirit of de Broglie and Einstein, we think the concepts of matter and radiation can be unified. We know a particle propagates like a wave; its motion is described by certain wave equations. At this point, it is not clear what the wave function represents. Besides the statistical meaning suggested by the Copenhagen interpretation, does the wave function represent any physical motion? For photon, we know it is an electro-magnetic wave. But what about particles with rest mass, such as an electron? To investigate the physical nature of matter wave, we propose that: (1) Like the photon, a particle is an excitation wave of a real physical field. (2) Different types of particles are different excitation modes of the same field. Based on this thinking, we show that the concept of quantum mechanics can be a natural extension of classical mechanics. By critically analyzing the transition from classical physics to quantum physics, we found a new physical meaning for the quantum wave function. This work suggests that various quantum wave equations, including the Klein-Gordon equation, the Dirac equation and the Schrodinger equation, could have a common base relating to the Basic Wave Equation of the matter wave. This work has some interesting implications. It suggests a possible way to explain the origin of visible matters and dark matters in our universe.
Starburst activity in a ROSAT narrow emission‐line galaxy

We present multiwaveband photometric and optical spectropolarimetric observations of the R = 15.9 narrow emission line galaxy R117 A which lies on the edge of the error circle of the ROSAT X-ray source R117 (from M c Hardy et al. 1998). The overall spectral energy distribution of the galaxy is well modelled by a combination of a normal spiral galaxy and a moderate-strength burst of star formation. The far infrared and radio emission is extended along the major axis of the galaxy, indicating an extended starburst. On positional grounds, the galaxy is a good candidate for the identification of R117 and the observed X-ray flux is very close to what would be expected from a starburst of the observed far infra-red and radio fluxes. Although an obscured high redshift QSO cannot be entirely ruled out as contributing some fraction of the X-ray flux, we find no candidates to K = 20.8 within the X-ray errorbox and so conclude that R117 A is responsible for a large fraction, if not all, of the X-ray emission from R117. Searches for indicators of an obscured AGN in R117 A have so far proven negative; deep spectropolarimetric observations show no signs of broad lines to a limit of one per cent and, for the observed far infra-red and radio emission, we would expect a ten times greater X-ray flux if the overall emission were powered by an AGN. We therefore conclude that the X-ray emission from R117 is dominated by starburst emission from the galaxy R117 A.
An Upper Limit to the Mass of Black Holes in the Halo of the Galaxy

If massive black holes constitute the dark matter in the halo surrounding the Milky Way, the existence of low-mass globular clusters in the halo suggests an upper limit to their mass, M BH . We use a combination of the impulse approximation and numerical simulations to constrain M BH ≤10 3 M ○. ; otherwise, several of the halo globular clusters would be heated to disruption within one-half of their lifetime. Taken at face value, this constraint is three orders of magnitude stronger than the previous limit provided by disk heating arguments. However, since the initial mass function of clusters is unknown, we argue that the real constraint is at most, an order of magnitude weaker
On the thinnest steady threads obtained by gravitational stretching of capillary jets

Abstract Experiments and global linear stability analysis are used to obtain the critical flow rate below which the highly stretched capillary jet, generated when a Newtonian liquid issues from a vertically oriented tube, is no longer steady. The theoretical description, based on the one-dimensional mass and momentum equations retaining the exact expression for the interfacial curvature, accurately predicts the onset of jet self-excited oscillations experimentally observed for wide ranges of liquid viscosity and nozzle diameter. Our analysis, which extends the work by Sauter & Buggisch (J. Fluid Mech. vol. 533, 2005, pp. 237–257), reveals the essential stabilizing role played by the axial curvature of the jet, the latter effect being especially relevant for injectors with a large diameter. Our findings allow us to conclude that, surprisingly, the size of the steady threads produced at a given distance from the exit can be reduced by increasing the nozzle diameter.
Intensity variations of geocoronal Balmer alpha emission: 1. Observational results

Ground-based observations of geocoronal Balmer α (Hα) emission were performed with a large-aperture, dual-etalon Fabry-Perot spectrometer at a resolving power of about 25,000, which clearly isolates the geocoronal emission from galactic and zodiacal light backgrounds. During each observing night, observations were conducted alternately between two directions, one at 60° zenith distance in the sun's azimuth and the other in the antisolar direction, to compare the emission primarily from single scattering of solar Lyman β with that primarily from multiple scattering, and to evaluate the intensity variations over various time scales. Accurate intensity calibration was obtained by observing astronomical photometric standard sources on each night of observation. The morning enhancement of the observed Hα intensities in both directions is 10%. Assuming single scattering dominates, the observed intensity variation seems difficult to reconcile with the standard diurnal variation model which implies an increase at mid-latitudes of about 30% in the exobase hydrogen density between the evening period and the post-midnight period. In contrast to the standard diurnal variation model, some satellite measurements indicate a morning hydrogen trough in northern mid-latitudes, a result which appears to be consistent with the present measurements. Detailed radiative transfer calculations and model refinements are required to clarify the situation. Comparisons of Hα intensities observed on different nights with the same scattering geometry reveal a clear inverse relationship between the geocoronal Hα emission rate and the exospheric temperature based on the Jacchia 1977 model. Preliminary calculation shows this Hα intensity variation agrees with the results of several satellite experiments which found that the variation of the exobase hydrogen density with temperature is less rapid than that predicted by consideration of Jeans escape as the only hydrogen escape mechanism.
Jet shapes in opaque media

We present general arguments, based on the medium-induced radiative energy loss, to explain the presence of nontrivial angular structures within this perturbative mechanism. Simple analytical estimates of this effect are provided which are relevant to the current discussion on the interpretation of the data on two- and three-particle correlations of semihard particles at BNL's Relativistic Heavy Ion Collider.
Eddy-current effect on resonant magnetoelectric coupling in magnetostrictive-piezoelectric laminated composites

An analytical model of resonant magnetoelectric (ME) coupling in magnetostrictive (MS)-piezoelectric (PE) laminated composites in consideration of eddy-current effect in MS layer using equivalent circuit method is presented. Numerical calculations show that: (1) the eddy-current has a strong effect on ME coupling in MS-PE laminated composites at resonant frequency; and (2) the resonant ME coupling is then significantly dependent on the sizes of ME laminated composites, which were neglected in most previous theoretical analyses. The achieved results provide a theoretical guidance for the practice engineering design, manufacture, and application of ME laminated composites and devices.
Signatures of unresolved binaries in stellar spectra: implications for spectral fitting

The observable spectrum of an unresolved binary star system is a superposition of two single-star spectra. Even without a detectable velocity offset between the two stellar components, the combined spectrum of a binary system is in general different from that of either component, and fitting it with single-star models may yield inaccurate stellar parameters and abundances. We perform simple experiments with synthetic spectra to investigate the effect of unresolved main-sequence binaries on spectral fitting, modeling spectra similar to those collected by the APOGEE, GALAH, and LAMOST surveys. We find that fitting unresolved binaries with single-star models introduces systematic biases in the derived stellar parameters and abundances that are modest but certainly not negligible, with typical systematic errors of $300\,\rm K$ in $T_{\rm eff}$, 0.1 dex in $\log g$, and 0.1 dex in $[\rm Fe/H]$ for APOGEE-like spectra of solar-type stars. These biases are smaller for spectra at optical wavelengths than in the near-infrared. We show that biases can be corrected by fitting spectra with a binary model, which adds only two labels to the fit and includes single-star models as a special case. Our model provides a promising new method to constrain the Galactic binary population, including systems with single-epoch spectra and no detectable velocity offset between the two stars.
Brane-induced gravity from asymmetric warped compactification

We show that brane-induced gravity can be realized as a low energy effective theory of brane worlds with asymmetric warped compactification. A self-accelerating universe without cosmological constant on the brane can be realized in a model where one side of the bulk has finite volume, but the other side has infinite volume. The spin-2 perturbations for brane-induced gravity and asymmetric warped compactification models have the same spectrum at low energies. For a de Sitter brane, the spin-2 graviton has mass in the range 0<m{sup 2}{<=}2H{sup 2}, with m{sup 2}=2H{sup 2} in the self-accelerating universe.