Photon Polarization Research Articles

VACUUM BIREFRINGENCE AND DICHROISM IN A STRONG PLANE-WAVE BACKGROUND

In the present study, we consider the effects of vacuum birefringence and dichroism in strong electromagnetic fields. According to quantum electrodynamics, the vacuum state exhibits different refractive properties depending on the probe photon polarization and one also obtains different probabilities of the photon decay via production of electron-positron pairs. Here we investigate these two phenomena by means of several different approaches to computing the polarization operator. The external field is assumed to be a linearly polarized plane electromagnetic wave of arbitrary amplitude and frequency. Varying the probe-photon energy and the field parameters, we thoroughly examine the validity of the locally-constant field approximation (LCFA) and techniques involving perturbative expansions in terms of the external-field amplitude. Within the latter approach, we develop a numerical method based on a direct evaluation of the weak-field Feynman diagrams, which can be employed for investigating more complex external backgrounds. The polarization operator depends on two parameters: classical nonlinearity parameter ξ and the product η = ωq0/m2 of the laser field frequency ω and the photon energy q0 (m is the electron mass). The domains of validity of the approximate techniques in the ξη plane are explicitly identified.

Quantum Pair Generation in Nonlinear Metasurfaces with Mixed and Pure Photon Polarizations.

Metasurfaces are highly effective at manipulating classical light in the linear regime; however, effectively controlling the polarization of nonclassical light generated from nonlinear resonant metasurfaces remains a challenge. Here, we present a solution by achieving polarization engineering of frequency-nondegenerate biphotons emitted via spontaneous parametric down-conversion in GaAs metasurfaces, utilizing quasi-bound states in the continuum (qBIC) resonances to enhance biphoton generation. Through comprehensive polarization tomography, we demonstrate that the emitted photons' polarization directly reflects the qBIC mode's far-field properties. Furthermore, we show that both the type of qBIC mode and the symmetry of the meta-atoms can be tailored to control each single-photon polarization state, and that the subsequent two-photon polarization states are nearly separable, offering potential applications in the heralded generation of single photons with adjustable polarization. This work provides a significant step toward utilizing metasurfaces to generate quantum light and engineer their polarization, a critical aspect for future quantum technologies.

Constraints on axionlike ultralight dark matter from observations of the HL Tauri protoplanetary disk

Dark matter may consist of axionlike particles (ALPs). When polarized electromagnetic radiation passes through the dark-matter media, interaction with background ALPs affects the polarization of photons. The condensate of axionic dark matter experiences periodic oscillations, and the period of the oscillations is of the order of years for ultralight dark matter. This would result in observable periodic changes in the polarization plane, determined by the phases of the ALP field at the Earth and at the source. In this paper, we use recent polarimetric observations of the HL Tauri protoplanetary disk performed in different years to demonstrate the lack of changes of polarization angles, and hence to constrain masses and photon couplings of the hypothetical axionlike ultralight dark matter. Published by the American Physical Society 2024

Magnetic Monopole Phenomenology at Future Hadron Colliders

Abstract In the grand tapestry of Physics, the magnetic monopole (MM) is a holy grail. Therefore, numerous efforts are underway in search of this hypothetical particle at CMS, ATLAS, and MoEDAL experiments of Large Hadron Collider (LHC) by employing different production mechanisms. The cornerstone of our comprehension of monopoles lies in Dirac’s theory which outlines their characteristics and dynamics. Within this theoretical framework, an effective U(1) gauge field theory, derived from conventional models, delineates the interaction between spin magnetically-charged fields and ordinary photons under electric–magnetic dualization. The focus of this paper is the production of MMs through Drell–Yan (DY) and the Photon-Fusion (PF) mechanisms to generate velocity-dependent scalar, fermionic, and vector monopoles of spin angular momentum 0 , 1 2 , 1 respectively at LHC. A computational study compares the monopole pair-production cross-sections for both methods at various center-of-mass energies ( s ) with different magnetic dipole moments. The comparison of kinematic distributions of monopoles at Parton and reconstructed level are demonstrated for both DY and PF mechanisms. Extracted results showcase how modern machine-learning techniques can be used to study the production of MMs at the future proton-proton particle colliders at 100 TeV. We demonstrate the observability of MMs against the most relevant Standard Model background using multivariate methods such as Boosted Decision Trees, Likelihood, and Multilayer Perceptron. This study compares the performance of these classifiers with traditional cut-based and counting approaches, proving the superiority of our methods.

Teaching quantum information science to secondary school students with photon polarization and which-path encoding

Research and curriculum development on quantum information science is a novel but technologically and socially significant challenge for physics education. While the debate is open on the core content, the approaches, and the strategies for addressing the need of effective instruction on the subject-matter, some indications have begun to emerge. Among them, the importance of an earlier start of education and of helping students develop not only a theoretical knowledge, but also high-level experimental skills including ideal design and conduction of experiments. Such skills are challenging to attain in existing traditional programs and may be considered inaccessible at introductory level because of the difficulties connected with qubit implementations. Here we present the design process, the structure, and a preliminary evaluation of a course for secondary school that is aimed to promote the building of a basic but integrated understanding of quantum information science, including experimental design and lab activities. The course was developed within the model of educational reconstruction, and embedded into a conceptual change framework in physics and computation. The encoding of polarization and which-path information of a photon is used to engage students in the development of a global model of logical encoding and processing, in ideal experimental design of gates and circuits, and in their implementation on the optical bench. Data show the effectiveness of the course in promoting student engagement in the modelling of gates in different encodings, in fostering an understanding of the computational role of physical setups, and a positive attitude and interest towards quantum computation and innovative teaching methods.

Electromagnetic Debye mass within Gribov–Zwanziger action

Abstract In the present study we have investigated the electromagnetic Debye mass by computing the static limit of the temporal component of the one-loop photon polarization tensor involving effective quarks in the loop. These effective quarks have been considered within the Gribov–Zwanziger action, thereby incorporating the necessary non-perturbative effects. As an academic exercise, we have also shown one of the applications of this Gribov modified Debye mass by using it to evaluate the real and imaginary parts of the heavy quark potential in a Quantum Electrodynamics (QED) system. This computation of the electromagnetic Debye mass and the corresponding estimations of the heavy quark potential can be seen as stepping stones in the direction of further practical Quantum Chromodynamics (QCD) calculations in the non perturbative domain.

Advances in hybrid strategies for enhanced photocatalytic water splitting: Bridging conventional and emerging methods

Significant efforts have been dedicated to hydrogen production through photocatalytic water splitting (PWS) over the past five decades. However, achieving commercially viable solar-to-hydrogen conversion efficiency in PWS systems remains elusive. These systems face intrinsic and extrinsic challenges, such as inadequate light absorption, insufficient charge separation, limited redox active sites, low surface area, and scalability issues in practical designs. To address these issues, conventional strategies including heterojunction engineering, plasmonics, hybridization, lattice defects, sensitization, and upconversion processes have been extensively employed. More recently, innovative hybrid strategies like photonic crystal-assisted and polarization field-assisted PWS have emerged, which improve light absorption and charge separation by harnessing the slow photon effect, multiple light scattering, and the piezoelectric, pyroelectric, and ferroelectric properties of materials. This review article aims to provide a comprehensive examination and summary of these new synergistic hybrid approaches, integrating plasmonic effects, upconversion processes, and photonic crystal photocatalysis. It also explores the role of temperature in suppressing exciton recombination during photothermic photocatalysis. This article also highlights emerging strategies such as the effects of magnetic fields, periodic illumination, many-body large-hole polaron, and anapole excitations, which hold significant potential to advance PWS technology and facilitate renewable hydrogen generation.

Polarization and Orbital Angular Momentum Encoded Quantum Toffoli Gate Enabled by Diffractive Neural Networks.

Controlled quantum gates play a crucial role in enabling quantum universal operations by facilitating interactions between qubits. Direct implementation of three-qubit gates simplifies the design of quantum circuits, thereby being conducive to performing complex quantum algorithms. Here, we propose and present an experimental demonstration of a quantum Toffoli gate fully exploiting the polarization and orbital angular momentum of a single photon. The Toffoli gate is implemented using the polarized diffractive neural networks scheme, achieving a mean truth table visibility of 97.27±0.20%. We characterize the gate's performance through quantum state tomography on 216 different input states and quantum process tomography, which yields a process fidelity of 94.05±0.02%. Our method offers a novel approach for realizing the Toffoli gate without requiring exponential optical elements while maintaining extensibility to the implementation of other three-qubit gates.

The excellent electrocatalytic HER activity and photogalvanic effect of WS2/Ga2O3 based on Density Functional Theory

This study is based on density functional theory, studied structure and electronic properties, optical properties, electrocatalytic water splitting to produce H2, and electrical properties of the WS2/Ga2O3 heterojunction. By analyzing the photoelectric characteristics, we find that the WS2/Ga2O3 heterojunction has built-in electric field, which can separate photogenerated carriers and effectively capture visible light for visible light photocatalysis. In addition, the change of Gibb free energy (ΔG) tends to 0, so when the WS2/Ga2O3 heterojunction is used as a catalyst, the hydrogen evolution reaction tends to proceed spontaneously. Interestingly, by analyzing the electrical properties, we find that the large and obviously changed photogalvanic effect photocurrent is produced with the change of polarization angle and photon energy of the WS2/Ga2O3 heterojunction, and it has the potential to become high-sensitivity optoelectronic detector.

Factorization of photon induced processes in ultra-peripheral heavy ion collisions

In this study, we investigate photon-photon scattering in ultra-peripheral heavy ion collisions (UPCs). We start by deriving an effective Lagrangian from first principles and then apply factorization techniques from Soft-Collinear effective theory (SCET). This approach allows us to decompose the photon-photon scattering cross-section into two primary factors: the generalized transverse momentum distributions (GTMDs) and the hard scattering amplitude. We further analyze the emission of soft photons by final state leptons, incorporating a soft function into the cross section through an evolution method. Our analysis yields detailed predictions for observable angular correlations among the final state leptons. Specifically, we calculate the angular correlations characterized by the azimuthal parameters 〈cos⁡2ϕ〉 and 〈cos⁡4ϕ〉, highlighting the influence of initial photons polarization and recoil effects from final state soft photons.

Non-reciprocity in photon polarization based on direction of polarizer under gravitational fields

Unification of gravity with quantum mechanics is still a terra incognita. Photon polarization measurements offer a unique window for probing the interaction between these two fundamental forces. We have revealed that non-reciprocity in the photon polarization angle can arise by tailoring the quantization axis, which corresponds to the direction of polarizer. Due to this non-reciprocity, the measured polarization angle can become ten times larger than that of gravitationally induced frame rotation in both near-Earth and black hole environments. To verify this finding, we propose an astronomical interferometer composed of satellites with the tailored quantization axis, challenging the conventional view of their triviality in closed paths of a photon. Notably, this non-reciprocity can extend to any rotation in the polarization plane, irrespective of the origins, all of which can dictate polarization rotation. Our findings could offer new opportunities for testing fundamental principles in physics.

A power spectrum approach to the search for axion-like particles from resolved galaxy clusters using CMB as a backlight

Axions or axion-like particles (ALPs) are hypothetical particles predicted by beyond standard model theories, which make one of the dark matter candidates. These particles can convert into photons and vice-versa in the presence of a magnetic field, with a probability decided by its coupling strength gaγ . One of the ways to detect these particles is by using the Cosmic Microwave Background (CMB) as a backlight. As the CMB photons pass through a galaxy cluster, they can get converted into ALPs in the mass range 10-15 eV to 10-11 eV through resonant conversion in the presence of cluster magnetic fields. This leads to a polarized spectral distortion (α-distortion) in the CMB as the photon polarization parallel to the magnetic field in the galaxy cluster is involved in the conversion. The fluctuations in the magnetic field and electron density in a galaxy cluster lead to spatially varying α-distortion around the cluster, with a power spectrum that is different from the lensed E-mode and B-mode CMB polarization power spectrum for the standard model of cosmology. By measuring the difference in the polarization power spectrum around a galaxy cluster from the all-sky signal, one can find new α-distortion in the sky. For the resolved galaxy clusters, if the redshift, electron density, and magnetic field profiles of the cluster can be constrained using optical, X-ray, and radio observations, one can measure the coupling strength gaγ from the ALP power spectrum. The contamination from CMB and galactic foregrounds such as synchrotron and dust can be mitigated by using multiple frequency bands by leveraging on the difference in the spectral shape of the signal from foregrounds. Using the ILC technique to clean the foregrounds, we show that the new power spectrum-based approach of the resolved galaxy clusters from upcoming CMB experiments such as Simons Observatory and CMB-S4 can detect (or put constraints) on the ALP-photon coupling strength of gaγ < 5.2 × 10-12 GeV-1 and gaγ < 3.6 × 10-12 GeV-1 at 95% C.I. respectively for ALPs of masses 10-13 eV or for smaller gaγ for lighter ALP masses.

Experimental observation of topological quantum criticality

We report on a photonic simulator of the critical state forming at the quantum phase transition between topologically distinct Anderson insulator phases. We observe a time-staggered profile in the circular photon polarization, which originates from the interplay of a chiral and sublattice symmetry, and has recently been suggested as a signature for topological Anderson criticality within the setup. We discuss the role of statistical detuning from criticality and show that the controlled breaking of phase coherence removes the signal, revealing its origin in quantum coherence. Published by the American Physical Society 2024

Photon propagation in a charged Bose–Einstein condensate model

We consider the propagation of photons in a model of a charged scalar Bose-Einstein (BE) condensate. We determine the dispersion relations of the collective modes, as well as the photon polarization tensor and the dielectric constant in the model. Two modes correspond to the transverse photon polarizations, with dispersion relations of the usual form for transverse photons in a plasma. The other two modes, denoted as the (±)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\pm )$$\\end{document} modes, are combinations of the longitudinal photon and the massive scalar field. Their dispersion relations behave very differently as functions of momentum. The (+)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(+)$$\\end{document} mode dispersion relation increases steadily and remains greater than the momentum as the momentum increases. The dispersion relation of the (-)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(-)$$\\end{document} mode decreases in a given momentum range, with the group velocity being negative in that range, while in another range it increases steadily but remains smaller than the momentum, akin to the situation in a medium with an index of refraction greater than 1. We consider the non-relativistic limit of the (±)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\pm )$$\\end{document} dispersion relations and discuss some aspects of the results. We also determine the wavefunctions of the (±)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\pm )$$\\end{document} modes, which are useful to obtain the corrections to the dispersion relations, e.g., imaginary parts due to the damping effects and/or the effects of scattering, due to the interactions with the excitations of the system. The results can be useful in various physical contexts that have been considered in the literature involving the electrodynamics of a charged scalar BE condensate.

Axion-like Particle Effects on Photon Polarization in High-Energy Astrophysics

In this review, we present a self-contained introduction to axion-like particles (ALPs) with a particular focus on their effects on photon polarization: both theoretical and phenomenological aspects are discussed. We derive the photon survival probability in the presence of photon–ALP interaction, the corresponding final photon degree of linear polarization, and the polarization angle in a wide energy interval. The presented results can be tested by current and planned missions such as IXPE (already operative), eXTP, XL-Calibur, NGXP, XPP in the X-ray band and like COSI (approved to launch), e-ASTROGAM, and AMEGO in the high-energy range. Specifically, we describe ALP-induced polarization effects on several astrophysical sources, such as galaxy clusters, blazars, and gamma-ray bursts, and we discuss their real detectability. In particular, galaxy clusters appear as very good observational targets in this respect. Moreover, in the very-high-energy (VHE) band, we discuss a peculiar ALP signature in photon polarization, in principle capable of proving the ALP existence. Unfortunately, present technologies cannot detect photon polarization up to such high energies, but the observational capability of the latter ALP signature in the VHE band could represent an interesting challenge for the future. As a matter of fact, the aim of this review is to show new ways to make progress in the physics of ALPs, thanks to their effects on photon polarization, a topic that has aroused less interest in the past, but which is now timely with the advent of many new polarimetric missions.

Improved Entanglement‐Based High‐Dimensional Optical Quantum Computation with Linear Optics

AbstractQuantum gates are the essential block for quantum computers. High‐dimensional quantum gates exhibit remarkable advantages over their 2D counterparts for some quantum information processing tasks. Here, a family of entanglement‐based optical controlled‐SWAP gates on is presented. With the hybrid encoding, the control qubits and target qudits are encoded in photonic polarization and spatial degrees of freedom, respectively. The circuit is constructed using only () linear optics, beating an earlier result of 14 linear optics with . The circuit depth five is much lower than an earlier result of 11 with . Besides, the fidelity of the presented circuit can reach 99.4%, and it is higher than the previous counterpart with . The scheme is constructed in a deterministic way without any borrowed ancillary photons or measurement‐induced nonlinearities. Moreover, the approach allows .

Machine learning assisted reconstruction of positron-on-target annihilation events in the PADME experiment

Abstract The PADME Experiment at the Laboratori Nationali di Frascati, INFN is used in the search for a Dark photon, produced with an ordinary photon in electron-positron annihilation events. The energy of the photons, emitted in the annihilation is measured using a segmented electromagnetic calorimeter. Machine learning methods consisting of various convolutional neural networks are used for the reconstruction of close-in-time signals with high resolution. These algorithms were used on two-photon annihilation events e + e − → γγ to calibrate the photon energy values. In order to calibrate the neural network output from signal amplitude to energy, the machine learning based results were compared to the conventional methods used for reconstructing the signals. The use of machine learning models for reconstructing real data and the process of calibrating the machine learning method output are presented and discussed.

Complete analysis of differential cross section in 7 Li + γ→→ 6 Li + n at astrophysical energies

We have carried out complete analysis of differential cross section in 7 Li + γ → 6 Li + n using model-independent theoretical formalism. A complete analysis of the reaction involves measurements of not only one state of linear polarization of the photon but also another state of linear polarization inclined to the first at 45◦ and two states of circular polarization of the photon. An analytical study of the differential cross section including all the photon polarization states is carried out at near-threshold energies of interest to Big Bang Nucleosynthesis.

Dual-Core Photonic Crystal Fiber Polarization Beam Splitter Based on a Nematic Liquid Crystal with an Ultra-Short Length and Ultra-Wide Bandwidth

This paper presents a novel pentagonal structure dual-core photonic crystal fiber polarizing beam splitter (PS-DC-PCF PBS) filled with a nematic liquid crystal (NLC) in the central hole. Unlike previous designs with symmetric arrangements, the upper and lower halves of the structure have different air hole arrangements. The upper half consists of air holes arranged in a regular quadrilateral pattern, while the lower half features a regular hexagonal arrangement of air holes. By filling the central hole with birefringent liquid crystal, the birefringence of the structure is enhanced, reducing the coupling lengths along the x polarization and y polarization directions. The polarization properties, coupling characteristics, and the influence of different structural parameters on the extinction ratio of the polarizing beam splitter are analyzed using the full-vector finite element method. Simulation results demonstrate that the designed PS-DC-PCF PBS achieves a maximum extinction ratio (ER) of 72.94 dB with a splitting length of only 61.9 μm and a wide operating bandwidth of 423 nm (1.324–1.747 μm), covering most of the O, E, S, C, L, and U communication bands. It exhibits not only ultra-short splitting lengths and ultra-wide splitting bandwidth but also good manufacturing tolerances and anti-interference capabilities. The designed PS-DC-PCF PBS could provide crucial device support for future all-optical communication systems and has potential applications in fiber optic communication or fiber laser systems.

Room temperature quantum emitters in aluminum nitride epilayers on silicon

Room temperature quantum emitters have been reported in aluminum nitride grown on sapphire, but until now they have not been observed in epilayers grown on silicon. We report that epitaxial aluminum nitride grown on silicon by either plasma vapor deposition or metal-organic vapor phase epitaxy contains point-like emitters in the red to near-infrared part of the spectrum. We study the photon statistics and polarization of emission at a wavelength of 700–750 nm, showing signatures of quantized electronic states under pulsed and CW optical excitation. The discovery of quantum emitters in a material deposited directly on silicon can drive integration using industry standard 300 mm wafers, established complementary metal-oxide-semiconductor control electronics, and low marginal-cost mass-manufacturing.