Photon Polarization Research Articles

Phase-polarization ensemble modulation effect of a BaTiO3 crystal film waveguide on Mach-Zehnder interferometer electrooptic intensity modulators.

In this work, based on the nonlinear electrooptic (EO) modulation model, the relationship between the polarization states and the birefringence modulation caused optical phase of c-axis barium titanate (BaTiO3) crystal film is investigated first. Then, under an ensemble effect of phase-polarization modulation (PPM), the photon polarization behavior of a lightwave in a BaTiO3 film waveguide and its dynamic conversion process is clearly presented. Further, the optical output and optical phase changes of a Mach-Zehnder interferometric (MZI) type EO intensity modulator based on a dynamic nonlinear optical birefringence modulation are theoretically modeled. As a result, the systematic simulations show that, for one-wave (2π) optical phase modulation (OPM), the full width at half-maximum of the output signal is efficiently compressed 30% more than the current OPM. Finally, the improvements of the MZI output signal by the PPM scheme are in accord with the experimental results.

Astrophysical information from the Rayleigh-Jeans Tail of the CMB

One of the explanations for the recent EDGES-LOW band 21 cm measurements of a strong absorption signal around 80 MHz is the presence of an excess radio background to the Cosmic Microwave Background (CMB). Such excess can be produced by the decay of unstable particles into small mass dark photons which have a non-zero mixing angle with electromagnetism. We use the EDGES-LOW band measurements to derive joint constraints on the properties of the early galaxies and the parameters of such a particle physics model for the excess radio background. A Bayesian analysis shows that a high star formation efficiency and X-ray emission of 4–7 × 1048 erg per solar mass in stars are required along with a suppression of star formation in halos with virial temperatures ≲ 2 × 104 K. The same analysis also suggests a 68 percent credible intervals for the mass of the decaying dark matter particles, it's lifetime, dark photon mass and the mixing angle of the dark and ordinary photon oscillation of [10-3.5, 10-2.4] eV, [101.1, 102.7] × 13.8 Gyr, [10-12.2, 10-10] eV and [10-7, 10-5.6] respectively. This implies an excess radio background which is ≈ 5.7 times stronger than the CMB around 80 MHz. This value is a factor ∼ 3 higher than the previous predictions which used a simplified model for the 21 cm signal.

Polarization of Photons Scattered by Ultra‐Relativistic Ion Beams

AbstractA theoretical investigation of the elastic resonant scattering of photons by ultra–relativistic and partially stripped ions is presented. Particular attention in the study is given to the angular distribution and polarization of scattered photons as “seen” in both the ion‐rest and laboratory reference frames. In order to evaluate these angular and polarization properties, the irreducible polarization tensor approach is combined with the density matrix theory. If, furthermore, the ion–photon coupling is treated within the electric dipole approximation, this framework enables one to obtain simple analytical expressions for both the emission pattern and the polarization Stokes parameters of the outgoing radiation. These (analytical) expressions for the , , and transitions are displayed and analyzed , that are of interest for the Gamma Factory project and whose realization is currently under discussion at CERN. Based on the performed analysis, it is demonstrated that the resonantly scattered photons can be strongly (linearly or circularly) polarized, and that this polarization can be well controlled by adjusting either the emission angle and/or the polarization state of the incident radiation. Moreover, the potential of the photon scattering for measuring the spin‐polarization of ion beams is also discussed in detail.

Photon absorption of two-dimensional nonsymmorphic Dirac semimetals

Two-dimensional Dirac semimetals have attracted much attention because of their linear energy dispersion and non-trivial Berry phase. Graphene-like 2D Dirac materials are gapless only within certain approximations, e.g., if spin-orbit coupling (SOC) is neglected. It has recently been reported that materials with nonsymmorphic crystal lattice possess symmetry-enforced Dirac-like band dispersion around certain high-symmetry momenta even in the presence of SOC. Here we calculate the optical absorption coefficient of nonsymmorphic semimetals, such as $\alpha$-bismuthene, which hosts two anisotropic Dirac cones with different Fermi velocities along $x$ and $y$ directions.We find that the optical absorption coefficient depends strongly on the anisotropy factor and the photon polarization. When a magnetic field is applied perpendicular to the plane of the material, the absorption coefficient also depends on an internal parameter we termed the mixing angle of the band structure. We further find that an in-plane magnetic field, while leaving the system gapless, can induce a Van-Hove singularity in the joint density of states: this causes a significant enhancement of the optical absorption at the frequency of the singularity for one direction of polarization but not for the orthogonal one, making the optical properties even more strongly dependent on polarization. Due to the anisotropy present in our model, the Dirac cones at two high-symmetry momenta in the Brillouin zone contribute very differently to the optical absorbance. Consequently, it might be possible to preferentially populate one valley or the other by varying photon polarization and frequency. These results suggest that nonsymmorphic 2D Dirac semimetals are excellent candidate materials for tunable magneto-optic devices.

An optimal swift key generation and distribution for QKD

Secured transmission between users is essential for communication system models. Recently, cryptographic schemes were introduced for secured transmission and secret transmission between cloud users. In a cloud environment, there are many security issues that occur among the cloud users such as, account hacking, data breaches, broken authentication, compromised credentials, and so on. Quantum mechanics has been implemented in cryptography that made it efficient for strong security concerns over outsourced data in a cloud environment. Therefore, the present research focuses on providing excellent security for cloud users utilizing a swift key generation model for QKD cryptography. The Quantum Key Distribution (QKD) is an entirely secure scheme known as Cloud QKDP. Initially, a random bit sequence is generated to synchronize the channel. An eavesdropper will not permit to synchronize parameters between them. In this key reconciliation technique, the random bit sequence is concatenated with the photon polarisation state. BB84 protocol is improved by optimizing its bit size using FireFly Optimization (FFO) at the compatibility state, and in the next state, both transmitter and receiver generate a raw key. Once the key is generated, it is then used for the transmission of messages between cloud users. Furthermore, a Python environment is utilized to execute the proposed architecture, and the accuracy rate of the proposed model attained 98 %, and the error rate is 2 %. This proves the performance of the proposed firefly optimization algorithm based swift key generation model for QKD performs better than previous algorithms.

Exclusive processes in ep collisions at the EIC and LHeC: A closer look on the predictions of saturation models

The exclusive production of vector mesons and photons in $ep$ collisions is investigated considering three phenomenological saturation models based on distinct assumptions for the treatment of the dipole-hadron scattering amplitude. The latest high precision HERA data for the reduced and vector meson cross sections are used to update the saturation model proposed by Marquet Peschanski, and Soyez, which predicts that the saturation scale is dependent of the squared momentum transfer $t$. The Marquet-Peschanski-Soyez predictions for the photon virtuality, energy and $t$ dependencies of the exclusive $\ensuremath{\rho}$, $J/\mathrm{\ensuremath{\Psi}}$, and deeply virtual Compton scattering cross sections are presented and a detailed comparison with the results derived using the impact parameter saturation models is performed. Our results indicate that a future experimental analysis of the $t$ distribution $d\ensuremath{\sigma}/dt$ for exclusive processes in the kinematical range that will covered by the EIC and LHeC, considering the distinct photon polarizations and large values of $t$, will be able to discriminate between the distinct approaches for the QCD dynamics at high energies.

A faithful solid-state spin-wave quantum memory for polarization qubits

Polarization-encoded qubits are particularly useful in quantum information tasks due to the easy transportation in a single spatial and temporal mode, the accurate qubit manipulation and the high robustness against decoherence. Reliable storage of polarization-encoded qubits is essential for the construction of large-scale quantum networks. Here we demonstrate a faithful quantum memory for photonic polarization qubits using the noiseless photon echo protocol implemented in a rare-earth-ion doped crystal (151Eu3+:Y2SiO5). Based on a detailed spectroscopic investigation on the 151Eu3+ ions at the site 2 of Y2SiO5 crystals, the qubit memory is implemented using a single piece of crystal which provides a near-uniform absorption for two orthogonal polarization states. A process fidelity of 0.919(24) is obtained for the storage of qubits carried by single-photon-level coherent pulses, which is beyond the maximal fidelity that can be achieved using the classical measure-and-prepare strategy. This compact device shall provide a useful solution for the construction of a long-lived transportable quantum memory and the memory-based quantum networks.

Ultra-Short Dual-Core Photonic Crystal Fiber Polarization Beam Splitter with Round Lattice and As2S3-Filled Center Air Hole

A circular ultra-short As2S3 filled double-core photonic crystal fiber polarization beam splitter is proposed. The finite element method is used to study the performance of the designed photonic crystal fiber polarization beam splitter. By filling high refractive index As2S3 into the central air hole, the coupling performance of the double-core PCF is improved. By optimizing geometric parameters, the splitting length of the circular beam splitter can be as short as 72.43 μm, and the extinction ratio can reach −151.42 dB. The high extinction ratio makes the circular polarization beam splitter have a good beam splitting function. The designed circular double-core photonic crystal fiber has the same cladding pore diameter, which is easier to prepare than other photonic crystal fibers with complex pore structure. Due to the advantages of high extinction ratio, extremely short beam splitting function and simple structure, the designed polarization beam splitter will be widely used in all-optical networks and optical device preparation.

An Algorithm to Calibrate and Correct the Response to Unpolarized Radiation of the X-Ray Polarimeter Onboard IXPE

Abstract The Gas Pixel Detector (GPD) is an X-ray polarimeter to fly onboard IXPE and other missions. To correctly measure the source polarization, the response of IXPE’s GPDs to unpolarized radiation has to be calibrated and corrected. In this paper, we describe the way such response is measured with laboratory sources and the algorithm to apply such correction to the observations of celestial sources. The latter allows to correct the response to polarization of single photons, therefore allowing great flexibility in all the subsequent analysis. Our correction approach is tested against both monochromatic and nonmonochromatic laboratory sources and with simulations, finding that it correctly retrieves the polarization up to the statistical limits of the planned IXPE observations.

Entanglement between Quantum Dots Electronic Spins and Circular Polarized Cavity Photons Due to the Spin-Orbit Interaction

Entanglement between Quantum Dots Electronic Spins and Circular Polarized Cavity Photons Due to the Spin-Orbit Interaction

Recent results on the positronium decay studies with the J-PET detector

Positronium, as a bound state of electron and positron and the lightest matter-antimatter system and at the same time an eigenstate of the C and P operators is a unique probe to search for possible violation of combined charge, parity, and time-reversal symmetries (CPT). The test is performed by a measurement of angular correlations in the annihilations of the lightest leptonic bound system. The J-PET detector is the only device which enables the determination of the polarization of photons from positronium annihilation together with the positronium spin axis on an event-by-event basis. This allows to explore a new class of discrete symmetry odd operators that were not investigated before. The first test of CPT symmetry at J-PET is presented together with preliminary results of CP, P and T symmetry test.

Photonic Angular Superresolution Using Twisted N00N States.

The increased phase sensitivity of N00N states has been used in many experiments, often involving photon paths or polarization. Here we experimentally combine the phase sensitivity of N00N states with the orbital angular momentum (OAM) of photons up to 100 ℏ, to resolve rotations of a light field around its optical axis. The results show that both a higher photon number and larger OAM increase the resolution and achievable sensitivity. The presented method opens a viable path to unconditional angular supersensitivity and accessible generation of N00N states between any transverse light fields.

Implementations of Heralded Solid‐State SWAP and SWAP$\sqrt {SWAP}$ Gates through Waveguide‐Assisted Interactions

AbstractSome heralded schemes are presented for realizing solid‐state quantum gates, including SWAP and gates. They are achieved by emitter‐photon scattering in 1D waveguides, and the qubits are encoded on the degenerate ground states of the solid‐state emitters. The schemes for these two quantum gates feature a filtering mechanism that the faulty scattering events between quantum emitters and photons can be mapped into the heralded photon losses. That is, the protocols can turn physical errors caused by system imperfections into the detection of photon polarization, which is advantageous for quantum information and quantum computation. Furthermore, no auxiliary solid‐state qubits are needed in our schemes, which reduces not only quantum resource but also error. The calculations reveal that the success probabilities and fidelities of the two quantum gates are high with current experimental technologies.

Theory and experiment for resource-efficient joint weak-measurement

Incompatible observables underlie pillars of quantum physics such as contextuality and entanglement. The Heisenberg uncertainty principle is a fundamental limitation on the measurement of the product of incompatible observables, a 'joint' measurement. However, recently a method using weak measurement has experimentally demonstrated joint measurement. This method [Lundeen, J. S., and Bamber, C. Phys. Rev. Lett. 108, 070402, 2012] delivers the standard expectation value of the product of observables, even if they are incompatible. A drawback of this method is that it requires coupling each observable to a distinct degree of freedom (DOF), i.e., a disjoint Hilbert space. Typically, this 'read-out' system is an unused internal DOF of the measured particle. Unfortunately, one quickly runs out of internal DOFs, which limits the number of observables and types of measurements one can make. To address this limitation, we propose and experimentally demonstrate a technique to perform a joint weak-measurement of two incompatible observables using only one DOF as a read-out system. We apply our scheme to directly measure the density matrix of photon polarization states.

Probing dark matter-cosmic ray electron interactions with circular polarisation of photons

Conventional indirect dark matter (DM) searches look for an excess in the electromagnetic emission from the sky that cannot be attributed to known astrophysical sources, but its polarisation has not been explored to date. In this proceeding, I argue that photon polarisation is an important feature to understand new physics interactions. Circular polarisation can be generated from Beyond the Standard Model interactions if they violate parity and there is an asymmetry in the number density of the initial state particles which participate in the interaction. I consider a simplified model for fermionic (Majorana) DM and study the circularly polarised gamma rays from DM cosmic ray electron interactions. I study the differential flux of positive and negative polarised photons from the Galactic Centre and show that the degree of circular polarization can reach up to 90%. Finally, I discuss the detection prospects of this signal in future experiments.

Feasibility study of measuring brightarrow sgamma photon polarisation in D^0rightarrow K_1(1270)^- e^+nu _e at STCF

We report a sensitive study of measuring brightarrow sgamma photon polarisation in D^{0}rightarrow K_1(1270)^-e^+nu _e with an integrated luminosity of mathscr {L} = 1 ab^{-1} at a center-of-mass energy of 3.773 GeV at a future Super Tau Charm Facility. More than 61,000 signals of D^{0}rightarrow K_1(1270)^-e^+nu _e are expected. Based on a fast simulation software package, the statistical sensitivity for the ratio of up-down asymmetry is estimated to be 1.5times 10^{-2} by performing a two-dimensional angular analysis in D^{0}rightarrow K_1(1270)^-e^+nu _e. Combining with measurements of up-down asymmetry in Brightarrow K_1gamma , the photon polarisation in brightarrow sgamma can be determined model-independently.

Geometric entanglement of a photon and spin qubits in diamond

Geometric nature, which appears in photon polarization, also appears in spin polarization under a zero magnetic field. These two polarized quanta, one travelling in vacuum and the other staying in matter, behave the same as geometric quantum bits or qubits, which are promising for noise resilience compared to the commonly used dynamic qubits. Here we show that geometric photon and spin qubits are entangled upon spontaneous emission with the help of the spin − orbit entanglement inherent in a nitrogen-vacancy center in diamond. The geometric spin qubit is defined in a degenerate subsystem of spin triplet electrons and manipulated with a polarized microwave. An experiment shows an entanglement state fidelity of 86.8%. The demonstrated entangled emission, combined with previously demonstrated entangled absorption, generates purely geometric entanglement between remote matters in a process that is insensitive of time, frequency, and space mode matching, which paves the way for building a noise-resilient quantum repeater network or a quantum internet.

Circular polarisation of gamma rays as a probe of dark matter interactions with cosmic ray electrons

Conventional indirect dark matter (DM) searches look for an excess in the electromagnetic emission from the sky that cannot be attributed to known astrophysical sources. Here, we argue that the photon polarisation is an important feature to understand new physics interactions and can be exploited to improve our sensitivity to DM. In particular, circular polarisation can be generated from Beyond the Standard Model interactions if they violate parity and there is an asymmetry in the number of particles which participate in the interaction. In this work, we consider a simplified model for fermionic (Majorana) DM and study the circularly polarised gamma rays below 10 GeV from the scattering of cosmic ray electrons on DM. We calculate the differential flux of positive and negative polarised photons from the Galactic Center and show that the degree of circular polarisation can reach up to 90%. Finally, once collider and DM constraints have been taken into account, we estimate the required sensitivity from future experiments to detect this signal finding that, although a distinctive peak will be present in the photon flux spectrum, a near future observation is unlikely. However, different sources or models not considered in this work could provide higher intensity fluxes, leading to a possible detection by e-ASTROGAM. In the event of a discovery, we argue that the polarisation fraction is a valuable characterisation feature of the new sector.

Dark photon bounds in the dark EFT

Dark photons are massive abelian gauge bosons that interact with ordinary photons via a kinetic mixing with the hypercharge field strength tensor. This theory is probed by a variety of different experiments and limits are set on a combination of the dark photon mass and kinetic mixing parameter. These limits can however be strongly modified by the presence of additional heavy degrees of freedom. Using the framework of dark effective field theory, we study how robust are the current experimental bounds when these new states are present. We focus in particular on the possible existence of a dark dipole interaction between the Standard Model leptons and the dark photon. We show that, under certain assumptions, the presence of a dark dipole modifies existing supernovæ bounds for cut-off scales up to mathcal{O} (10–100 TeV). On the other hand, terrestrial experiments, such as LSND and E137, can probe cut-off scales up to mathcal{O} (3 TeV). For the latter experiment we highlight that the bound may extend down to vanishing kinetic mixing.

Higher-order kinematical effects in deeply virtual Compton scattering

We study the deeply virtual Compton scattering cross-section in twist-two generalized parton distribution (GPD) approximation, and show that different choices of light-cone vectors and gauges for the final photon polarization will lead to different higher-order kinematical corrections to the cross-section formula. The choice of light-cone vectors affects kinematic corrections at the twist-three level, accounting for the differences between the cross-section formulas in the literature. On the other hand, kinematical corrections from higher-twist GPDs should eliminate the light-cone dependence at twist three. Those light-cone dependencies are studied systematically at JLab 12 GeV and future EIC kinematics. They serve as the intrinsic systematic uncertainties in extracting the Compton form factors through the cross-section formula. More importantly, they are also necessary for understanding cross-section measurements with higher-twist precision and to reconstruct higher-order Compton form factors.