Photon Emission Spectra Research Articles

Topological single-photon emission from quantum emitter chains

We propose a scheme for generating highly indistinguishable single photons from an active quantum Su-Schrieffer-Heeger chain composed of a collection of noisy quantum emitters. Strikingly, the single photon emission spectrum of the active quantum chain is exceedingly narrow relative to that of a single emitter or a topologically trivial chain. Furthermore, this effect is amplified dramatically in proximity to the non-trivial-to-trivial phase transition point. Exploiting this effect, we demonstrate that the single-photon linewidth of a long topological quantum chain can be arbitrarily reduced, rendering it an ideal source of indistinguishable single photons. Finally, by analyzing the most critical parameters concerning experimental realization and providing a microscopic and quantitative analysis of our model, we take concrete examples of actual quantum emitters to establish the viability of our proposal.

Accelerated electron thermometer: observation of 1D Planck radiation

Abstract We report on the observation of thermal photons from an accelerated electron via examination of radiative beta decay of free neutrons measured by the RDK II collaboration. The emitted photon spectrum is shown to corroborate a thermal distribution consistent with the dynamical Casimir effect. Supported by a robust chi-squared statistic, we find the photons reside in a 1D Planck spectrum with a temperature predicted by the moving mirror model. Subject Indices: B50 (Electromagnetic processes and properties), D29 (Nuclear decays and radioactivities (including fission)), and E76 (Quantum field theory on curved space)

Simple Scenario of Photons Emission from Anti Charm–Gluon Interaction using QCD Theory

In this work, the chromodynamics (QCD) theory was used to investigate the photon rate which was produced in interactions of anti-charm with gluon. The simple quantum scenario theory was implemented to give the rate equation that describes the collision of quark and gluon at a chemical potential .The photon emission rate was evaluated from the anti-charm-gluon interaction of the cg → dγ collision at the temperature of the system in the range of 180 - 360 MeV with different critical temperatures (e.g. 116.575, 139.891, 157.377 and 174.863 MeV) with photons energy GeV under the assumption that fugacity of quark and gluon are =0.08 and =0.02 respectively . The photon rate increases with decreasing the coupling of quark and gluon according to a decrease in the temperature of the system from 360 MeV to 180 MeV. The photon emission spectrum was calculated and discussed using a photon energy of 1GeV to 10GeV with different critical temperatures. In terms of QCD theory, the quantitative accomplishment was made for a unique six-flavor number nf = 4 + 2 of photon emission. The photon rate reaches minimum with photon energy E=10 GeV, it reflects the less coupling for the cg → dγ interaction.

Photon emission spectrum of ion pumps.

As the sensitivity of gravitational-wave detectors increases, new sources of noise appear. A potential source of noise may arise from charge accumulating on the mirrors of the experiment, the origin of which can be related to UV photons from the surroundings. In order to test one hypothesis, we measured the photon emission spectrum from a type of ion pump that is used in the experiment, an Agilent VacIon Plus 2500 l/s. We found that there is significant emission of UV photons above 5eV, capable of knocking electrons off mirrors or surrounding surfaces and charging them. Photon emission measurements were taken as a function of gas pressure, ion-pump voltage setting, and type of pumped gas. The overall emission and shape of the measured photon spectrum are consistent with bremsstrahlung as the mechanism for the production of the photons.

Impact of the anode tilt on photon emission spectrum and temperature rise in an x-ray tube

In radiology, the photon fluence and the energy spectrum generated from an x-ray tube may depend on the anode tilt angle. In this contribution, a Monte Carlo investigation is performed to quantify this effect by modeling an x-ray tube based on published data Bujila R. et al (2020 Physica. Med. 75 44–54). The GATE simulation code is used for this purpose. The calculations have moreover confirmed this dependence; the tilt of the anode could be used to increase the photon fluence. The thermal analysis has shown that the hot spot size is dependent as well on the anode tilt angle. The thermal focus temperature (ΔT) decreases when the anode tilt angle increases. Finally, by moving the acquisition angle from 293°–337° to 248°–292° and changing the anode tilt angle from 8° to 28°, the photon fluence can be increased by 55%.

Theoretical Calculation of Photon Emission from Quark-Antiquark Annihilation Using QCD Theory

In this work, we calculate and analyze the photon emission from quark and anti-quark interaction during annihilation process using simple model depending on phenomenology of quantum chromodynamic theory (QCD). The parameters, which include the running strength coupling, temperature of the system and the critical temperature, carry information regarding photon emission and have a significant impact on the photons yield. The emission of photon from strange interaction with anti-strange is large sensitive to decreases or increases there running strength coupling. The photons emission increases with decreases running strength coupling and vice versa. We introduce the influence of critical temperature on the photon emission rate in order to facilitate its further applied in photon emission spectrum. Photon emission was increased with large critical temperature MeV comparing with photons emission at critical temperature MeV. We analyze and discuss the sensitive of the emission of photon to photons energy . It increases with decreased photons energy and vice versa. However, the photons emission increases with increases thermal energy of system T = 170 MeV to 270 Mev. It is implied that strength coupling, critical temperature and photons energy can be as important as thermal energy of system for emission of photon.

Enhanced photon emission by field emission resonances and local surface plasmon in tunneling junction

We investigated the photon emission spectra on Ag (111) surface excited by tunneling electrons using a low temperature scanning tunneling microscope in ultrahigh vacuum. Characteristic plasmon modes were illustrated as a function of the bias voltage. The one electron excitation process was revealed by the linear relationship between the luminescence intensity and the tunneling current. Luminescence enhancement is observed in the tunneling regime for the relatively high bias voltages, as well as at the field emission resonance with bias voltage increased up to 9 V. Presence of a silver (Ag) nanoparticle in the tunneling junction results in an abnormally strong photon emission at the high field emission resonances, which is explained by the further enhancement due to coupling between the localized surface plasmon and the vacuum. The results are of potential value for applications where ultimate enhancement of photon emission is desired.

Proper orthogonal decomposition of continuum-dominated emission spectra for simultaneous multi-property measurements

A novel spectrum calibration method is proposed for high-accuracy emission spectroscopy to extract quantitative gas property information from the spontaneous photon emission spectra. This is challenging, particularly in the presence of broadband emission, which smears the characteristic local spectral features that are often used as property indicators in conventional emission spectroscopy. Proper orthogonal decomposition (POD) can reduce the dimension (ND) of the broadband spectrum profile by selecting a number (NM≪ND) of dominant bases that span the gas-property-dependent spectrum space. Each POD-decomposed spectral basis represents critical broadband spectral features that are sensitive to the gas properties of interest. A reduced-order model (ROM) employing the kriging method correlates the entire emission spectrum profile that decomposed by the bases to multiple gas properties. To provide a spectrum database to train the ROM, chemiluminescence was captured from a flat flame with varied diluent gas compositions (N2 and CO2), fuel-oxidizer equivalence ratios, and pressures (1–5 bar). Subsequently, the ROM employing an emission spectrum can predict the gas properties under high-temperature and high-pressure conditions where conventional sensors are inapplicable. The average relative prediction errors obtained using this new analysis method were approximately 3.2% and 1.3% for the pressure and equivalence ratio, respectively.

Universal model of strong coupling at the nonlinear resonance in open cavity-QED systems

Many molecular, quantum-dot, and optomechanical nanocavity-QED systems demonstrate strong nonlinear interactions between electrons, photons, and phonon (vibrational) modes. We show that such systems can be described by a universal model in the vicinity of the nonlinear resonance involving all three degrees of freedom. We solve the nonperturbative quantum dynamics in the strong-coupling regime of the nonlinear resonance, taking into account quantization, dissipation, and fluctuations of all fields. We find analytic solutions for quantum states in the rotating-wave approximation which demonstrate tripartite quantum entanglement once the strong-coupling regime is reached. We show how the strong coupling at the nonlinear resonance modifies photon emission and vibrational spectra, and how the observed spectra can be used to extract information about relaxation rates and the nonlinear coupling strength in specific systems.

Improving the accuracy of hard photon emission by sigmoid sampling of the quantum-electrodynamic table in particle-in-cell Monte Carlo simulations.

Research on laser-plasma interaction in the quantum-electrodynamic (QED) regime has been greatly advanced by particle-in-cell and Monte Carlo simulations (PIC-MC). While these simulations are widely used, we find that a noticeable numerical error arises due to inappropriate implementation of the quantum process accounting for hard photon emission and pair production in the PIC-MC codes. The error stems from the low resolution of the QED table used to sample photon energy, which is generated in the logarithmic scale and cannot resolve high energy photons. We propose a sampling method via sigmoid function that handles both the low energy and high energy end of the photon emission spectrum. It guarantees the accuracy of PIC-MC algorithms for hard photon radiation and other related processes in the strong-field QED regime.

Real-time feedback-driven single particle tracking spectroscopy

Real-time feedback-driven single particle tracking (RTFD-SPT) spectroscopy is an emerging technique to observe fast heterogeneous behavior and transient phenomena of biomolecules in their native environment. This is exemplified by single-molecule spectroscopic measurements such as photon antibunching, fluorescence lifetimes, and emission spectra, all on particles freely diffusing in solution. The use of these techniques by the community, however, has been limited, both by lack of awareness of their potential and barriers to adoption.

Spontaneous decay of artificial atoms in a three-qubit system

We study the evolution of qubits amplitudes in a one-dimensional chain consisting of three equidistantly spaced noninteracting qubits embedded in an open waveguide. The study is performed in the frame of single-excitation subspace, where the only qubit in the chain is initially excited. We show that the dynamics of qubits amplitudes crucially depend on the value of $kd$, where $k$ is the wave vector, $d$ is a distance between neighbor qubits. If $kd$ is equal to an integer multiple of $\pi$, then the qubits are excited to a stationary level. In this case, it is the dark states which prevent qubits from decaying to zero even though they do not contribute to the output spectrum of photon emission. For other values of $kd$ the excitations of qubits exhibit the damping oscillations which represent the vacuum Rabi oscillations in a three-qubit system. In this case, the output spectrum of photon radiation is determined by a subradiant state which has the lowest decay rate. We also investigated the case with the frequency of a central qubit being different from that of the edge qubits. In this case, the qibits decay rates can be controlled by the frequency detuning between the central and the edge qubits.

Spontaneous decay of artificial atoms in a multi-qubit system

We consider a one-dimensional chain of N equidistantly spaced noninteracting qubits embedded in an open waveguide. In the frame of single-excitation subspace, we systematically study the evolution of qubits' amplitudes if the only qubit in the chain was initially excited. We show that the temporal dynamics of qubits' amplitudes crucially depend on the value of kd, where k is the wave vector, d is a distance between neighbor qubits. If kd is equal to an integer multiple of π, then the qubits are excited to a stationary level which scales as N−1. We show that in this case, it is the dark states which prevent qubits from decaying to zero even though they do not contribute to the output spectrum of photon emission. For other values of kd the excitations of qubits have the form of damping oscillations, which represent the vacuum Rabi oscillations in a multi-qubit system. In this case, the output spectrum of photon radiation is defined by a subradiant state with the smallest width.

Spontaneous PT-symmetry breaking in lasing dynamics

Parity-time (PT) symmetric lasers exploit the modulation of optical gain and loss and have led to important fundamental demonstrations in non-Hermitian physics. The current theoretical analysis of PT-symmetric laser physics is performed on the basis of the adiabatic elimination of the medium polarization. This approximation doesn’t hold true for a more general optical system with strong photon-particle interactions, where the Rabi oscillation of active particles plays a non-negligible role in the lasing action. Here, we propose a model that takes into account the internal dynamics of active particles and numerically investigate the PT symmetry of macroscopic- and microscopic-sized laser systems that operate in the strong-coupling regime. The distinct phase diagrams are drawn according to the features of intracavity photon numbers and emission spectra. Our work extends the PT-symmetric optics from the weak- to the strong-coupling limit, potentially paving the way towards nonclassical PT-symmetric light sources for integrated photonic networks and ultrasensitive sensors.

Evaluating Brightness and Spectral Properties of Click Beetle and Firefly Luciferases Using Luciferin Analogues: Identification of Preferred Pairings of Luciferase and Substrate for In Vivo Bioluminescence Imaging

PurposeCurrently, a variety of red and green beetle luciferase variants are available for bioluminescence imaging (BLI). In addition, new luciferin analogues providing longer wavelength luminescence have been developed that show promise for improved deep tissue imaging. However, a detailed assessment of these analogues (e.g., Akalumine-HCl, CycLuc1, and amino naphthyl luciferin (NH2-NpLH2)) combined with state of the art luciferases has not been performed. The aim of this study was to evaluate for the first time the in vivo brightness and spectral characteristics of firefly (Luc2), click beetle green (CBG99), click beetle red 2 (CBR2), and Akaluc luciferases when paired with different d-luciferin (d-LH2) analogues in vivo.ProceduresTransduced human embryonic kidney (HEK 293T) cells expressing individual luciferases were analyzed both in vitro and in mice (via subcutaneous injection). Following introduction of the luciferins to cells or animals, the resulting bioluminescence signal and photon emission spectrum were acquired using a sensitive charge-coupled device (CCD) camera equipped with a series of band pass filters and spectral unmixing software.ResultsOur in vivo analysis resulted in four primary findings: (1) the best substrate for Luc2, CBG99, and CBR2 in terms of signal strength was d-luciferin; (2) the spectra for Luc2 and CBR2 were shifted to a longer wavelength when Akalumine-HCl was the substrate; (3) CBR2 gave the brightest signal with the near-infrared substrate, NH2-NpLH2; and (4) Akaluc was brighter when paired with either CycLuc1 or Akalumine-HCl when paired with d-LH2.ConclusionWe believe that the experimental results described here should provide valuable guidance to end users for choosing the correct luciferin/luciferase pairs for a variety of BLI applications.

Wavelength discrimination (WLD) TOF-PET detector with DOI information

Depth-of-interaction (DOI) encoding can contribute to improving spatial resolution uniformity and sensitivity in positron-emission-tomography (PET) scanners. In addition, time-of-flight (TOF) PET scanners with DOI encoding have received considerable interest because of their potential for improving the spatial resolution, sensitivity, and image quality of the overall system. In this study, a new DOI detector configuration utilizing scintillators’ emission wavelength is proposed, and experimental results on the energy, timing, and DOI performance of the detector are provided.The DOI information from the proposed phoswich-type detector can be acquired at the detector level without complex signal processing by utilizing a single optical filter with customized optical properties. For this, we used either a short pass filter (SPF) or a long pass filter (LPF) that allows light photons of a specific wavelength to pass. The two-layered phoswich detector was configured with two scintillators with different photon-emission spectra. In this study, we used Ce:GAGG (3 mm × 3 mm × 10 mm) and LYSO:Ce (3 mm × 3 mm × 10 mm) as the top and bottom layer scintillators, respectively. A digital silicon photomultiplier (dSiPM) was used as the photosensor and for data acquisition. The phoswich detector was placed in the center of two dSiPM pixels, where one of the dSiPM pixels was covered with the optical filter, and the light guide was placed on the other pixel. The detector was tested for energy, timing, and DOI encoding performance.When an SPF was used, the energy resolutions of 16.2% and 11.8% were achieved for the Ce:GAGG (top layer) and LYSO:Ce (bottom layer) respectively without correcting for saturation effect. With a small (3 mm × 3 mm × 5 mm) LYSO crystal as the reference detector, CRTs (coincidence-resolving times) of 338 ps and 244 ps were recorded for the top and bottom layers respectively. The detector configuration also provides an excellent DOI-separation figure-of-merit (FoM) value of 1.9.In the case of LPF, the energy resolutions of 12.0% and 12.9% were achieved for the Ce:GAGG (top layer) and LYSO:Ce (bottom layer), respectively. CRTs (coincidence resolving times) of 314 ps and 263 ps were recorded for the top and bottom layers, respectively. The DOI-separation FoM value of 1.5 was achieved in this setup.Results show that the proposed method can provide excellent discrete DOI positioning accuracy without compromising the timing performance of the detector.

Near-field negative electroluminescent cooling via nanoparticle doping

Modulating the photon tunneling probability is the key to control the near-field radiative heat transfer (NFRHT) between two objects. It has been found that nanoparticle doping technology can enable plentiful resonance modes which significantly adjust photon emission spectra. In this work, we theoretically analyze the performance of a near-field negative electroluminescent refrigeration (NFNELR) system consisting a Mie-metamaterial emitter and mercury cadmium telluride (MCT) receiver with spacing between them less than the thermal wavelength. The emitter consists of graphene/SiC core-shell (GSCS) nanoparticle-embedded thin film of Si deposited on bulk Si. We show that with the inclusion of GSCS nanoparticles, the thin layer of Mie-metamaterial acts like an effective medium that excites radiative heat transfer for the photons above the band gap of MCT. We analyze NFNELR performance for various bias voltages, various cryogenic temperatures, various volume fractions and various chemical potentials of GSCS nanoparticles. We also would like to emphasize that in order to improve the performance of the NFNELR system, the host matrix materials chosen are not necessarily stationary. These results provide a powerful way to rouse and regulate the NFRHT, meanwhile in turn, open up a way to explore actual development and present some guidance for optimal design of NFRHT.

Nonequilibrium states of a plasmonic Dicke model with coherent and dissipative surface-plasmon–quantum-emitter interactions

Hybrid photonic-plasmonic nanostructures allow one to engineer coupling of quantum emitters and cavity modes accounting for the direct coherent and environment mediated dissipative pathways. Using generalized plasmonic Dicke model, we explore the non-equilibrium phase diagram with respect to these interactions. The analysis shows that their interplay results in the extension of the superradiant and regular lasing states to the dissipative coupling regime and an emergent lasing phase without population inversion having boundary with the superradiant and normal states. Calculated photon emission spectra are demonstrated to carry distinct signatures of these phases.

CMB spectral distortions constraints on primordial black holes, cosmic strings and long lived unstable particles revisited

We calculate the spectral distortions from Hawking evaporation of primordial black holes before the epoch of recombination, taking into account emission of all standard model particles, including quark and gluons, and evolving the resulting particle cascades in the expanding Universe. We show that the constraints on the abundance of primordial black holes are stronger by more than an order of magnitude compared to the previous calculations which take only the primary photon emission into account. We also show that the shapes of the spectral distortions is different from the y or i-type distortions and are sensitive to the mass of the primordial black holes. We also extend previous constraints on the decay of long lived unstable particles before recombination to additional decay channels. We show that for dark matter mass ≲ 1 GeV, the spectral distortion shape is a function of the dark matter mass as well as the decay channel to standard model particles. We also provide new spectral distortion constraints on superconducting cosmic string decay. We explicitly show that consideration of emitted photon spectrum from string decay is not only important for the future experiments but also for already available COBE-FIRAS data.

Growth and properties of centimeter-sized lead free all inorganic perovskite Cs2AgBiBr6 crystal by additive CH3COONa

Cs2AgBiBr6 is a very promising lead-free double perovskite semiconductor material for low limit x-ray detection. However, the limited size of only 3–4 mm single crystals have been reported using inverse temperature crystallization method recently. To grow larger single crystals of Cs2AgBiBr6, only one, two or three single crystals should be grown during the spontaneous crystallization process. We have found that additive CH3COONa can solve this problem of the numbers of as-grown crystals. Single crystal Cs2AgBiBr6 with the maximum size of 13 mm has been successfully grown by cooling the solution with additive 30% CH3COONa. The Powder X-ray diffraction pattern of (1 1 1) plane revealed that the as-grown crystal had a good single crystallinity. Based on the single crystal, the optical transmission spectra, optical transmission microscopy image, temperature dependent photon-emission spectra and current–voltage properties have also been investigated. Therefore, CH3COONa is a suitable additive agent to grow larger Cs2AgBiBr6 single crystal with centimeter size.