Extra Photon Research Articles

Effects of torsion charge on optical appearance and additional photon rings of an asymmetric thin-shell wormhole

In this paper, we study the optical properties of asymmetric thin-shell wormholes (ATWs) under torsion charge. Utilizing the cut-and-paste method developed by Visser, we construct these wormholes and determine their key physical properties, such as the radius of the photon sphere and critical impact parameters, under different torsion charges. Furthermore, we investigate the effective potential and behavior of photon motion within the wormhole spacetime, identifying a relationship between photon trajectories and impact parameters. The study focuses on scenarios where thin accretion disks act as the primary light source. It reveals that the optical features of ATWs under torsion charge significantly differ from those of black holes (BHs). Notably, an increase in torsion charge leads to a reduction in the sizes of both extra photon rings and lensing bands, which serve as important markers for distinguishing and characterizing ATW spacetimes from those of BHs.

Observational appearance and extra photon rings of an asymmetric thin-shell wormhole with a Bardeen profile* *Supported by the National Natural Science Foundation of China (11903025), the Science and Technology Program of Sichuan Province, China(2023ZYD0023), and the starting fund of China West Normal University (18Q062)

In this work, the optical appearance of an asymmetric thin-shell wormhole with a Bardeen profile is studied. To initiate the process, we need to construct an asymmetric thin-shell wormhole utilizing the cut-and-paste technique proposed by Visser and subsequently ascertain its pertinent physical quantities such as the radius of the photon sphere and critical impact parameters for different values of magnetic charge g. Then, the effective potential and motion behavior of photons are also investigated within the framework of asymmetric thin-shell wormholes with a Bardeen profile. It can be found that the effective potential, ray trajectory, and azimuthal angle of the thin-shell wormhole exhibit a strong correlation with the mass ratio of black holes. By considering the accretion disk as the sole background light source, we observe additional photon rings and lensing bands in the optical appearance of the asymmetric thin-shell wormhole with a Bardeen profile compared to those exhibited by the Bardeen black hole. One can find that there is an increase in the size of the specific additional light bands with increasing magnetic charge g, which is different from the black hole case. These exceptionally luminous rings can serve as a robust criterion for the identification and characterization of the thin-shell wormhole spacetime.

Assisted Postselective Quantum Transformations and an Improved Photon Number Splitting Attack Strategy

Postselective transformations of quantum states is a broader class of operations than deterministic quantum channels. Here, we describe the possibility of increasing the success probability of postselective operations by using additional information, which has a form of pure quantum states and should not be changed in case of success. We describe the conditions under which assistance becomes useful, and provide application of our method which improves the efficiency of photon number splitting attack for a variant of SARG04 quantum key distribution protocol. In our attack scenario, one extra photon, which is unchanged, plays the role of assistance.

Ultrasensitive Optical Rotation Detection With Closed-Loop Suppression of Spin Polarization Error

Optical rotation detection system (ORDS) utilizing quantum nondemolition (QND) measurement methods is widely applied in the field of quantum metrology and quantum information. However, the sensitivity of ORDS is limited by the uncertainty from optical-couple noise during the measurement of the atomic spin ensemble. In this study, we specifically analyze the mechanism of optical-couple noise caused by the fluctuations of probe light’s polarization in the modulated ORDS with a new model established to describe atomic spin precession in this particular condition. It is discovered that transverse electron-spin polarization errors are generated by the residual probe photon spin polarization in the ORDS, which results in extra coupling magnetic noise. In order to suppress this noise, a novel in situ method is proposed that the resultant electron-spin errors are reduced by a specifically designed closed-loop system. The results are verified through the ORDS in a co-magnetometer. After zeroing the extra probe photon spin polarization, an angular sensitivity better than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1 \times 10 ^{\mathrm {-8}}$ </tex-math></inline-formula> rad/Hz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathrm {1/2}}$ </tex-math></inline-formula> is achieved for frequencies higher than 5 Hz, demonstrating a probe background noise of 0.26 fT/Hz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\mathrm {1/2}}$ </tex-math></inline-formula> @14.5 Hz, approaching electronic noise and photon shot noise (PSN). With closed-loop control, the optical rotation bias instability is promoted by 4.2 times (from 107.9 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$25.7 \mu $ </tex-math></inline-formula> rad/h), and the angular noise of the ORDS is reduced by 2.4 times at 1–100 Hz. The measurement uncertainty of the realized ORDS nears the standard quantum limit, paving the road for long-term ultrasensitive measurements for new physics explorations.

TeV and keV–MeV Excesses as Probes for Hadronic Process in BL Lacertaes

Abstract A hard TeV γ-ray component excess over the single-zone leptonic model prediction (TeV excess) is observed in the spectral energy distributions (SEDs) of some BL Lacs. Its origin is uncertain. We revisit this issue with four BL Lacs (1ES 0229+200, 1ES 0347–121, 1ES 1101–232, and H2356–309), in which the TeV excess is detected in their intrinsic SEDs. We represent their SEDs with a single-zone leptohadronic model, where radiations of the electrons and protons as well as the cascade electrons produced by the γγ and pγ interactions within their jets are considered. We show that the observed SEDs below the GeV gamma-ray band are attributed to the synchrotron radiations and self-Compton process of the primary electrons, and the TeV excess is explained with the γ-ray emission from the pγ process via the π 0 decay. The cascade emission of the electrons produced via the γγ and pγ interactions results in a keV–MeV excess in the SEDs, illustrated as a bump or plateau. This extra photon field enhances the production of TeV photons from the p γ process, resulting in a reduction of the proton power by about one order of magnitude. However, the derived powers are still 3–4 orders of magnitude larger than the Eddington limit, being challenged by the current black hole accretion physics. Applying our model to Mrk 421, we propose that synergic observations with current and upcoming TeV and keV–MeV telescopes for its tentative TeV and MeV excesses can give insights to the hadronic process in its jet.

Gamma-ray line from electroweakly interacting non-abelian spin-1 dark matter

We study gamma-ray line signatures from electroweakly interacting non-abelian spin-1 dark matter (DM). In this model, Z2-odd spin-1 particles including a DM candidate have the SU(2)L triplet-like features, and the Sommerfeld enhancement is relevant in the annihilation processes. We derive the annihilation cross sections contributing to the photon emission and compare with the SU(2)L triplet fermions, such as Wino DM in the supersymmetric Standard Model. The Sommerfeld enhancement factor is approximately the same in both systems, while our spin-1 DM predicts the larger annihilation cross sections into γγ/Zγ modes than those of the Wino by frac{38}{9} . This is because a spin-1 DM pair forms not only J = 0 but also J = 2 partial wave states where J denotes the total spin angular momentum. Our spin-1 DM also has a new annihilation mode into Z2-even extra heavy vector and photon, Z′γ. For this mode, the photon energy depends on the masses of DM and the heavy vector, and thus we have a chance to probe the mass spectrum. The latest gamma-ray line search in the Galactic Center region gives a strong constraint on our spin-1 DM. We can probe the DM mass for ≲ 25.3 TeV by the Cherenkov Telescope Array experiment even if we assume a conservative DM density profile.

Extreme ultraviolet photon effect on ionization and recombination of high-order harmonic generation

The extreme ultraviolet (XUV) pulse effect on the ionization and recombination of the high-order harmonic generation has been theoretically studied. It is shown that (i) with the introduction of a shorter duration XUV pulse to a fundamental infrared (IR) pulse, the XUV photon can only be absorbed during the electron ionization process. Thus, the harmonic signal can be enhanced due to the XUV resonance transition and ionization. (ii) With the introduction of a longer-duration XUV pulse to a fundamental IR pulse, the XUV photon can be absorbed not only in the electron ionization process, but also in the electron recombination process. As a result, not only the harmonic signal can be improved, but also the harmonic cutoff can be extended with an additional XUV photon energy region (. Moreover, as the XUV intensity increases, much more XUV photons can be absorbed in the electron recombination process, thus leading to the harmonic cutoff extension with the extra photon energy region of .

Parallel, multi-purpose Monte Carlo code for simulation of light propagation in segmented tissues

We have developed a massive-parallel, multi-purpose Monte Carlo (MC) code for simulation of light propagation in complex structures modelled with e.g. magnetic resonance images. The code is designed to execute parallel threads on a Linux-based cluster of computers equipped with multiple graphical processing units (GPU) utilizing NVidia CUDA technology. We show steps one can take to implements such code itself. Furthermore, we provide methodology of building a MRI-based head model and populating it with realistic optical properties at excitation and fluorescence emission wavelengths during inflow of fluorescence agent (indocyanine green – ICG). The proposed code provides following original features: (i) Simulation of fluorescence light propagation in media with spatial distribution of multiple different fluorophores characterized by concentration, quantum yield and fluorescence lifetime. (ii) The fluorescence light tracking does not need extra photon tracking and works in parallel with tracking photons at the excitation wavelength, introducing execution time overhead of 0.02% only. (iii) Calculation of high-resolution spatial distributions of sensitivity factors mapping voxels absorption change to parameters measured on a model surface: statistical parameters (moments) of the distribution of time of flight of photons. (iv) Random number generators states are preserved between runs to greatly improve calculation time of the sensitivity factors. (v) Simulation of fluorescence lifetime wide field imaging in diffusively scattering media. The code is designed to handle big models, divided into e.g. 200 million voxels or more, which other methods struggle to handle. Simulations on a human head model with 0.3 mm voxel size require 2 GB of a GPU memory only. This is supported by developed non-standard floating-point data storage format. The proposed code is cross-validated with field-leading MC and finite element methods on the same hardware environment for varying model sizes and temporal resolutions. Tests revealed competitive execution time and high temporal resolution of boundary data for high spatial resolution of MRI-based head model.

Spinel-Type nitride compounds with improved features as solar cell absorbers

Ternary spinel nitrides are a new class of semiconductor materials with tunable bandgap in the visible range. In this work, we report a rational design of spinel-type nitride compounds with improved features as solar cell absorber materials by way of the in-gap-band (IGB) concept. For this purpose, a systematic screening on the effect of transition metal (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Mo) hyperdoping on the crystal and electronic structure properties of germanium (Ge) and tin (Sn) spinel nitrides (γ-(MmSnx-mGe1-x)3N4, x = 0.5, m = 0.042, 0.083) was carried out through accurate ab-initio methods. The analysis of the electronic structure reveals that M-hyperdoped ternary spinel nitrides with M = Cr, Co, Cu show an IGB with the adequate properties to allow two extra photon absorption processes. A detailed study of the sunlight absorption properties, and maximum photovoltaic efficiencies reveal that Co-hyperdoped spinel is an excellent candidate to be used in photovoltaic devices as absorber material, with maximum photovoltaic efficiency of ~ 55%. Overall, our results suggest that it would be possible to design new ternary spinel-type nitride materials with improved absorption properties suitable for potential use in photovoltaic applications.

Stimulatory effect of exposure to low-power-density 2.45 GHz microwaves on Arabidopsis thaliana seedlings in vitro

Communication technologies are moving toward higher microwave frequencies and bandwidths to satisfy the growing demand for high data rates. The concern about the possible effects of microwaves on plants and animals has increased recently. There is still uncertainty concerning the effects of microwaves on plants. The present study was conducted to investigate the effect of industrial, scientific and medical (ISM) radio band microwaves on seedlings and seeds of Arabidopsis thaliana (L.). In vitro growing A. thaliana wild-type seedlings and seeds were exposed to 2.45 GHz continuous-wave microwaves at a power flux density of 1.0 ± 0.1 W m−2 for 48 h. Microwave exposure increased the hydrogen peroxide content, photosynthetic pigments, nonphotochemical quenching and fluorescence of the seedlings, while peroxidase activity and Fv/Fm values were unchanged. Anthocyanin and malondialdehyde were decreased. Seed germination rate, fresh weight and photosynthetic pigment contents of 10-day-old seedlings obtained from microwaves exposed seeds remained unchanged. Results confirmed the inexistence of oxidative stress but a stimulatory effect of microwave on A. thaliana seedlings. The increased hydrogen peroxide content and nonphotochemical quenching suggest acceptance of extra photon energy and a portion of the excess captured photon passing through the photosystem, while a portion of energy dissipated as heat.

Observation of Extra Photon Recoil in a Distorted Optical Field.

Light carries momentum which induces on atoms a recoil for each photon absorbed. In vacuum, for a monochromatic beam of frequency ν, the global momentum per photon is bounded by general principles and is smaller than hν/c leading to a limit on the recoil. However, locally this limit can be broken. In this Letter, we give a general formula to calculate the recoil in vacuum. We show that in a laser beam with a distorted optical field, there are regions where the recoil can be higher than this limit. Using atoms placed in those regions we are able to measure directly the extra recoil.

Non-Markovian rotational relaxation matrix for fast collisions between two linear molecules in high-pressure gaseous media. I. General formalism and preliminary testing.

Collisional mixing of (vib)rotational lines appearing in spectroscopic signatures of dense planetary atmospheres and combustion environments is rigorously handled for the case of two linear colliders in terms of incomplete (non-Markovian) collisions related to off-energy-shell scattering amplitudes. Contrary to the standard impact-approximation approaches valid solely in band-centre regions, a new uniform broadband spectrum description is developed on the basis of a frequency-dependent rotational relaxation matrix which accurately accounts for the influence of the extra photon energy with respect to the molecular transitions. This matrix is built using a symmetric Liouville-space metric and obeys all known fundamental rules. Its direct calculation from refined potential-energy surfaces and promising modeling methods for forthcoming practical computations are outlined. A simple preliminary test for N2-N2 isotropic Raman line widths argues in favor of considerable effects of the internal perturber's structure on modeled spectral characteristics.

Superfluid–Mott-insulator quantum phase transition of light in a two-mode cavity array with ultrastrong coupling

In this paper we construct a new type of cavity array, in each cavity of which multiple two-level atoms interact with two independent photon modes. This system can be totally governed by a two-mode Dicke-lattice model, which includes all of the counter-rotating terms and therefore works well in the ultrastrong coupling regime achieved in recent experiments. Attributed to its special atom-photon coupling scheme, this model supports a global conserved excitation and a continuous $U(1)$ symmetry, rather than the discrete $Z_{2}$ symmetry in the standard Dicke-lattice model. This distinct change of symmetry via adding an extra photon mode strongly impacts the nature of photon localization/delocalization behavior. Specifically, the atom-photon interaction features stable Mott-lobe structures of photons and a second-order superfluid-Mott-insulator phase transition, which share similarities with the Jaynes-Cummings-lattice and Bose-Hubbard models. More interestingly, the Mott-lobe structures predicted here depend crucially on the atom number of each site. We also show that our model can be mapped into a continuous $XX$ spin model. Finally, we propose a scheme to implement the introduced cavity array in circuit quantum electrodynamics. This work broadens our understanding of strongly-correlated photons.

Asking for an extra photon in Higgs production at the LHC and beyond

We study the inclusive production of a Higgs boson in association with a high-$p_T$ photon at the LHC, detailing the leading-order features of the main processes contributing to the $H\gamma$ final state. Requiring an extra hard photon in Higgs production upsets the cross-section hierarchy for the dominant channels. The $H\gamma$ inclusive production comes mainly from photons radiated in vector-boson fusion (VBF), which accounts for about 2/3 of the total rate, for $p_T^{\gamma,j} >30$ GeV, at leading order. On the other hand, radiating a high-$p_T$ photon in the main top-loop Higgs channel implies an extra parton in the final state, which suppresses the production rate by a further $\alpha_S$ power. As a result, the $H\gamma$ production via top loops at the LHC has rates comparable with the ones arising from either the $H t\bar t$ production or the $HW(Z)\gamma$ associated production. Then, in order of decreasing cross section, comes the single-top-plus-Higgs channel, followed in turn by the heavy-flavor fusion processes $b\bar b \to H\gamma$ and $c\bar c \to H\gamma$. The $H\gamma$ production via electroweak loops has just a minor role. At larger c.m. energies, the $H t\bar t\gamma$ channel surpasses the total contribution of top-loop processes. In particular, requiring $p_T^{\gamma,j} >30$ GeV at $\sqrt S \simeq 100$ TeV, $H t\bar t\gamma$ accounts for about $1/4$ of the inclusive $H\gamma$ production at leading order, about half of the total being due to VBF production.

Exact formula of the spectrum of the pseudoscalar octet

Non-perturbative proof is presented of a generalized version of Goldstone theorem, where the Lagrangian conserves an approximate SU(3) chiral symmetry, that both quark masses and electromagnetism make contributions to the masses of spinless particles of pseudoscalar octet. We show that apart from what comes in the form of some projections of a two-body Bethe–Salpeter amplitude for which the photon lines like the gluon ones are all internal in the case of neutral pseudo-Goldstone bosons, the charged pseudoscalar mesons receive additional contributions that may be expressed in terms of the axial–vectorial projection of a three-body Bethe–Salpeter amplitude with an extra external photon line.

Using a 2D detector array for meaningful and efficient linear accelerator beam property validations.

Following linear accelerator commissioning, the qualified medical physicist is responsible for monitoring the machine's ongoing performance, detecting and investigating any changes in beam properties, and assessing the impact of unscheduled repairs. In support of these responsibilities, the authors developed a method of using a 2D ionization chamber array to efficiently test and validate important linear accelerator photon beam properties. A team of three physicists identified critical properties of the accelerator and developed constancy tests that were sensitive to each of the properties. The result was a 14‐field test plan. The test plan includes large and small fields at varying depths, a reduced SSD field at shallow depth for sensitivity to extra focal photon and electron components, and analysis of flatness, symmetry, dose, dose profiles, and dose ratios. Constancy tests were repeated five times over a period of six weeks and used to set upper and lower investigation levels at ±3 SDs. Deliberate variations in output, penumbra, and energy were tested to determine the suitability of the proposed method. Measurements were also performed on a similar, but distinct, machine to assess test sensitivity. The results demonstrated upper and lower investigation levels significantly smaller than the comparable TG‐142 annual recommendations, with the exception of the surrogate used for output calibration, which still fell within the TG‐142 monthly recommendation. Subtle changes in output, beam energy, and penumbra were swiftly identified for further investigation. The test set identified the distinct nature of the second accelerator. The beam properties of two photon energies can be validated in approximately 1.5 hrs using this method. The test suite can be used to evaluate the impact of minor repairs, detect changes in machine performance over time, and supplement other machine quality assurance testing.PACS numbers: 87.56bd, 87.56Fc

Even-parity states of the Sm atom with stepwise excitation

Two-colour stepwise excitation and photoionization schemes are adopted to study the spectra of high-lying states of the Sm atom. These bound even-parity states are excited with three different excitation paths from the 4f66s6p7DJ (J = 1, 2, 3) intermediate states, respectively. They are probed by photoionization process with an extra photon driving them to the continuum states. In this experiment, 270 states are detected in an energy range from 36160 cm−1 to 42250 cm−1, 109 of which are newly discovered, while the rest of them are confirmed to be the energy levels reported previously. Furthermore, based on the J-momentum selection rules of three excitation paths, a unique assignment of J-momentum for all observed states is determined, eliminating all remaining ambiguities in the literature. Finally, 53 single-colour transitions originating from the scanning laser are also identified. For all the relevant transitions, the information about their relative intensities is also given in the paper.

Photoionization spectra of even-parity states of Sm atom with multistep excitation

Two-color stepwise excitation and photoionization schemes are adopted to study the spectra of bound even-parity high-lying states of the Sm atom with three different excitation paths via the 4f 66s6p 7D J ( J=1, 2 and 3) intermediate states. In order to obtain the information of these high-lying states, the Sm atom in these high-lying states is photoionized with an extra photon. Among 231 states detected in the energy region between 35,545 and 44,225 cm −1, 108 states are newly discovered, while the rest can be identified as the same with the literature. In most cases, comparisons of the spectra corresponding to the three different excitation paths may partially determine the total angular momentum of the observed peaks with the selection rules. In addition, the relative intensities of all related transition lines are given.

Scanning multiple mice in a small-animal PET scanner: Influence on image quality

To achieve high throughput in small-animal positron emission tomography (PET), it may be advantageous to scan more than one animal in the scanner’s field of view (FOV) at the same time.However, due to the additional activity and increase of Poisson noise, additional attenuating mass, extra photon scattering, and radial or axial displacement of the animals, a deterioration of image quality can be expected. In this study, the NEMA NU 4-2008 image quality (NU4IQ) phantom and up to three FDG-filled cylindrical “mouse phantoms” were positioned in the FOV of the Siemens Inveon small-animal PET scanner to simulate scans with multiple mice. Five geometrical configurations were examined. In one configuration, the NU4IQ phantom was scanned separately and placed in the center of the FOV (1C). In two configurations, a mouse phantom was added with both phantoms displaced radially (2R) or axially (2A). In two other configurations, the NU4IQ phantom was scanned along with three mouse phantoms with all phantoms displaced radially (4R), or in a combination of radial and axial displacement (2R2A). Images were reconstructed using ordered subset expectation maximization in 2 dimensions (OSEM2D) and maximum a posteriori (MAP) reconstruction. Image quality parameters were obtained according to the NEMA NU 4-2008 guidelines. Optimum image quality was obtained for the 1C geometry. Image noise increased by the addition of phantoms and was the largest for the 4R configuration. Spatial resolution, reflected in the recovery coefficients for the FDG-filled rods, deteriorated by radial displacement of the NU4IQ phantom (2R, 2R2A, and 4R), most strongly for OSEM2D, and to a smaller extent for MAP reconstructions. Photon scatter, as indicated by the spill-over ratios in the non-radioactive water- and air-filled compartments, increased by the addition of phantoms, most strongly for the 4R configuration. Application of scatter correction substantially lowered the spill-over ratios, but caused an over-correction for the recovery coefficients of the FDG-filled rods when the phantom was displaced radially. Image noise was not substantially influenced by scatter correction. In conclusion, when scanning 2 mice, axial displacement (2A) is preferable above to radial displacement (2R) since for axial displacement, the recovery coefficients are higher and spill-over ratios are lower, whereas image noise remains similar. In the case of scanning 4 mice, combined axial and radial displacement (2R2A) is preferable to just radial displacement (4R).

GRB090111: extra soft steep-decay emission and peculiar rebrightening

Abstract We present a detailed study of GRB090111, focusing on its extra soft power-law photon index Γ &amp;gt; 5 at the very steep-decay phase emission (power-law index α= 5.1, steeper than 96 per cent of gamma-ray bursts detected by Swift) and the following peculiar X-ray rebrightening. Our spectral analysis supports the hypothesis of a comoving band spectrum with the peak of the νFν spectrum evolving with time to lower values: a period of higher temporal variability in the 1–2 keV light curve ends when the Epeak evolves outside the energy band. The X-ray rebrightening shows extreme temporal properties when compared to a homogeneous sample of 82 early flares detected by Swift. While an internal origin cannot be excluded, we show these properties to be consistent with the energy injection in refreshed shocks produced by slow shells colliding with the fastest ones from behind, well after the internal shocks that are believed to give rise to the prompt emission have ceased.