Maximum Number Of Photons Research Articles

Improving the resolution and light yield in CsI(Tl) scintillators

In the search for Dark Matter, very low-energy sensitive detectors are needed that would be able to distinguish minute differences in closely residing energy peaks. To increase the ability of CsI(Tl) scintillator detectors to do so, a different wrapping material will be used on the innermost layer of the detector. This wrapping material is a 3MTM Enhanced Specular Reflector (ESR) material which is hypothesized to produce a higher light yield with better resolution than the PTFE wrapping of plumber’s tape due to its high reflectivity. Two different types of measurements were carried out to test this hypothesis. Each test was run on a different half of a CsI(Tl) rectangular crystal of volume 48 in3. First, a source of 60Co was used to test the difference between the wrappings. The test was run an hour for the PTFE and the ESR wrapping. We observe a 35% increase in the ADC count for each 60Co energy peak and 15% decrease in the value of the standard deviation around those peaks. Secondly, a source of 241Am was used to test the low-energy capabilities of the ESR material. Here also we see a significant increase in the ADC count for the two energy peaks of the 241Am source. Due to the high photon reflectivity capability of the ESR film, our detector is more capable of collecting photons created by low-energy interactions. As we know Dark Matter produces very low-energy recoils, while interacting with the detector target material, so the ability to contain a maximum number of photons within the detector volume will help us move one step closer to detecting the rare interaction. Because of this significant increase in light yield and general decrease in standard deviation, it is clear that the ESR material has a greater ability to gather higher resolution data than its predecessor. This could lead to a greater understanding of low-energy particles, which in turn could help us understand what Dark Matter really is.

Paired-objectives photon enhancement (POPE) microscopy.

Fluorescence microscopy techniques are widely employed for the visualization, localization, and observation of structures and dynamics in biological samples. In order to obtain optimal image resolution, collecting the maximum number of photons from each fluorophore is essential. Historically, researchers have addressed this need by increasing the excitation energy, engineering higher numerical aperture (NA) objectives, improving the quantum yield of fluorophores, and/or escalating the quantum efficiency of detectors. While these approaches have led to great advances in the field of microscopy, they cannot proceed linearly in a limitless manner. We noticed that more than half of photons are lost as fluorophores emit in a direction other than the objective of either an upright or inverted microscope. To collect these lost photons, we have developed a new system called paired-objectives photon enhancement (POPE) microscopy to increase photon capture of a fluorophore by nearly two-fold. This system captures these lost photons by aligning an 8f optical system and mirror directly opposite the lower objective of an inverted microscope, thereby reflecting more emitted fluorescence back through the lower objective and into the detector. Through the additive effect of the initial fluorescence and the reflected fluorescence combining, the number of photons captured nearly doubles. This improved photon budget allows a microscopy imaging system to have better optical resolution, higher sensitivity, and/or faster detection speed. This new technique has been demonstrated in confocal light microscopy, epifluorescence microscopy, and super-resolution light microscopy and can, in theory, be applied in a modular fashion to any and all other fluorescence microscopy methods.

Analysis of [formula omitted] in the presence of a circularly polarized laser field

In this study, we have investigated the production of a charged Higgs boson in association with a charged weak W-boson (H±W∓) at tree level via e+e− annihilation in the presence of a laser field with circular polarization. At first step and by using analytical techniques, we have derived the expression of the differential cross section involving both Z and γ diagrams. Next, we have shown that the cross section of this process inside the laser field is proportional to the form factor FHWV, and it depends on the mass of charged Higgs boson and the center-of-mass energy. Then, we have analyzed the dependence of total laser-assisted cross section on the number of photons exchanged for two different cases of form factor. Finally, we have found that the maximum number of photons that can be transferred depends only on the laser parameters.

Efecto de la temperatura en la cristalización de películas de perovskita-ch3 nh3 pbi3 -xclx

In the present manuscript, the effect of temperature on crystallisation of perovskite thin films (CH3NH3PbI3-xClx) was analysed (perovskite films are utilized to produce perovskite-based solar cells that appear to be devices with lower production costs and higher efficiency than silicon-based solar cells). To synthesise the perovskite films, four samples with precursor solution were spin coated for 45 s at 2000 rpm. After that, the samples were annealed at three different temperatures. Likewise, samples were characterised by UV/Vis Spectroscopy, Emission Spectroscopy, Fluorescence Microscopy, and ImageJ software were used to analyse crystal size. It was found that the sample annealed at 80 oC presented the highest fluorescence emission with 49539.09 CPS and the best particle size distribution. Band Gap Energy (Eg) was also calculated resulting in 1.60 ± 0.01 eV (An ideal solar cell has a band gap of 1.4 eV to absorb the maximum number of photons from the solar radiation).

Estimation of Gaussian random displacement using non-Gaussian states

In continuous-variable quantum information processing, quantum error correction of Gaussian errors requires simultaneous estimation of both quadrature components of displacements on phase space. However, quadrature operators $x$ and $p$ are non-commutative conjugate observables, whose simultaneous measurement is prohibited by the uncertainty principle. Gottesman-Kitaev-Preskill (GKP) error correction deals with this problem using complex non-Gaussian states called GKP states. On the other hand, simultaneous estimation of displacement using experimentally feasible non-Gaussian states has not been well studied. In this paper, we consider a multi-parameter estimation problem of displacements assuming an isotropic Gaussian prior distribution and allowing post-selection of measurement outcomes. We derive a lower bound for the estimation error when only Gaussian operations are used, and show that even simple non-Gaussian states such as single-photon states can beat this bound. Based on Ghosh's bound, we also obtain a lower bound for the estimation error when the maximum photon number of the input state is given. Our results reveal the role of non-Gaussianity in the estimation of displacements, and pave the way toward the error correction of Gaussian errors using experimentally feasible non-Gaussian states.

Free-electron lasing at 27 nanometres based on a laser wakefield accelerator.

X-ray free-electron lasers can generate intense and coherent radiation at wavelengths down to the sub-ångström region1-5, and have become indispensable tools for applications in structural biology and chemistry, among other disciplines6. Several X-ray free-electron laser facilities are in operation2-5; however, their requirement for large, high-cost, state-of-the-art radio-frequency accelerators has led to great interest in the development of compact and economical accelerators. Laser wakefield accelerators can sustain accelerating gradients more than three orders of magnitude higher than those of radio-frequency accelerators7-10, and are regarded as an attractive option for driving compact X-ray free-electron lasers11. However, the realization of such devices remains a challenge owing to the relatively poor quality of electron beams that are based on a laser wakefield accelerator. Here we present an experimental demonstration of undulator radiation amplification in the exponential-gain regime by using electron beams based on a laser wakefield accelerator. The amplified undulator radiation, which is typically centred at 27 nanometres and has a maximum photon number of around 1010 per shot, yields a maximum radiation energy of about 150 nanojoules. In the third of three undulators in the device, the maximum gain of the radiation power is approximately 100-fold, confirming a successful operation in the exponential-gain regime. Our results constitute a proof-of-principle demonstration of free-electron lasing using a laser wakefield accelerator, and pave the way towards the development of compact X-ray free-electron lasers based on this technology with broad applications.

Computational analysis of octagonal torus-shaped nano meta-atom through fractional absorption bandwidth for applications in the terahertz regime

In this paper, we present a computational analysis method for the study of silicon dioxide (SiO2) graphene-based and amorphous silicon (a-Si)-graphene based nano meta-atoms in the terahertz (THz) regime. The proposed meta-atoms were modeled using a SiO2 substrate, optimized using a-Si substrate, and “sandwiched” between graphene layers. The octagonal-shaped torus was geometrically designed as a 3D structure to achieve optimal electromagnetic wave absorption from separate atoms. The upper and lower tori had identical diagonal arms to capture the maximum number of photons with minimal absorption losses. Graphene was chosen as the upper and ground layer material to optimize the electrical and optical properties of our proposed nano metamaterial. Finally, the following four fractional bandwidths with absorption percentages were optimized from the simulation: 4 bands (225.7–254.74 THz, 99.8%; 356.64–401.1 THz, 97.28%; 525.4 THz, 99.19%; 656.34 THz, 94.94%). The multi-band fractional absorption characteristic in the THz regime highlighted our proposed nano meta-atom as a potential candidate for absorption in the infrared and visible spectrum.

Calculation of the Universal Gravitational Constant, of the Hubble Constant, and of the Average CMB Temperature

Dirac made the hypothesis that all large, dimensionless numbers that could be constructed from the important natural units of cosmology and atomic theory were connected [1] [2]. Although Dirac did not succeed in exactly matching all these numbers, he suspected that there was a way to unify all of them. Dirac’s hypothesis leads to the N constant which unifies most of physics’ parameters. It represents the maximum number of photons with a wavelength equal to the universe circumference. Using a new cosmological model, we found the β constant which represents the ratio between the expansion speed of matter in the universe and the speed of light. With these constants, we can now calculate accurately several physics parameters, including the universal gravitational constant G, the Hubble constant H0, and the average temperature T of the cosmological microwave background (CMB). Our equations show that G, H0 and T are not really constant over space and time.

IR Transceiver Irradiation Characteristics on Bubble/Slug Flow Regimes in Conventional and Minichannels

Multiphase fluid flows commonly occur in petrochemical, biotech, food, and process industries. Extraction and flow of crude oil is an example of multiphase solid, liquid, and gas flows. In this paper, the output signal characteristics of an infrared (IR) transceiver sensing system during the two-phase flows of air–water mixture inside a 2.64 mm diameter and 0.30-mm-thick glass tube is presented. An optimized distance between IR LED (transmitter) and center of the test section is predicted using COMSOL Multiphysics so that the receiver senses maximum number of photons. The experiments are done for the optimized distance to analyze bubble/slug of varying length and shapes. High-speed imaging is used for image registration of the flow regimes. A numerical model is developed with COMSOL package to understand the signal characteristics for multiple bubble/slug of varying sizes and is validated with the experimental results. Also with the developed model, a method is proposed to predict the liquid film thickness in mini/microtubes of diameters 3.42, 1.51, and 0.62 mm inner diameter and 0.60-, 1.50-, and 2.57-mm thickness, respectively. The results can be used to design IR transceiver array to measure the liquid film thickness in two-phase flow online.

Statistical sensitivity of phase measurements via laser-induced fluorescence with optical cycling detection

In atomic and molecular phase measurements using laser-induced fluorescence detection, optical cycling can enhance the effective photon detection efficiency and hence improve sensitivity. We show that detecting many photons per atom or molecule, while necessary, is not a sufficient condition to approach the quantum projection limit for detection of the phase in a two-level system. In particular, detecting the maximum number of photons from an imperfectly closed optical cycle reduces the signal-to-noise ratio (SNR) by a factor of $\sqrt{2}$, compared to the ideal case in which leakage from the optical cycle is sufficiently small. We derive a general result for the SNR in a system in terms of the photon detection efficiency, probability for leakage out of the optical cycle per scattered photon, and the product of the average photon scattering rate and total scattering time per atom or molecule.

Squeezed-state evolution and entanglement in lossy coupled-resonator optical waveguides

We investigate theoretically the temporal evolution of a squeezed state in lossy coupled-cavity systems. We present a general formalism based upon the tight binding approximation and apply this to a two-cavity system as well as to a coupled resonator optical waveguide in a photonic crystal. We derive analytical expressions for the number of photons and the quadrature noise in each cavity as a function of time when the initial excited state is a squeezed state in one of the cavities. We also analytically evaluate the time dependant cross correlation between the photons in different cavities to evaluate the degree of quantum entanglement. We demonstrate the effects of loss on the properties of the coupled-cavity systems and derive approximate analytic expressions for the maximum photon number, maximum squeezing and maximum entanglement for cavities far from the initially excited cavity in a lossless coupled resonator optical waveguide.

BREMSSTRAHLUNG FORMATION IN THE DUAL ENERGY METHOD FOR RADIOGRAPHY OF THE UNAUTHORIZED EMBEDDING

The possibility of an effective method of dual-energy radiography unauthorized inclusions containing heavy elements in cargo containers has been investigated. A method for optimizing the energy performance of the bremsstrahlung radiation: low-energy beam (containing the maximum number of photons in the energy range, which is dominated by Compton effect) and high energy beam (with a maximum number of high-energy photons, electron-positron pairs) has been developed. The influence of the converter thickness and converter material on the spectral characteristics of the beams of photons has been investigated. The variants of treelayers efficient converters have been proposed. On the basis of the Monte Carlo and quasi-analytical method a numerical experiment radiography investments has been completed. It is shown that the use of optimally shaped beams can reliably distinguish embeddingfrom lead to masking the background of steel structures up to 25 cm

Photoactivation of Luminescent Centers in Single SiO2 Nanoparticles

Photobleaching of fluorophores is one of the key problems in fluorescence microscopy. Overcoming the limitation of the maximum number of photons, which can be detected from a single emitter, would allow one to enhance the signal-to-noise ratio and thus the temporal and spatial resolution in fluorescence imaging. It would be a breakthrough for many applications of fluorescence spectroscopy, which are unachievable up to now. So far, the only approach for diminishing the effect of photobleaching has been to enhance the photostability of an emitter. Here, we present a fundamentally new solution for increasing the number of photons emitted by a fluorophore. We show that, by exposing a single SiO2 nanoparticle to UV illumination, one can create new luminescent centers within this particle. By analogy with nanodiamonds, SiO2 nanoparticles can possess luminescent defects in their regular SiO2 structure. However, due to the much weaker chemical bonds, it is possible to generate new defects in SiO2 nanostructures using UV light. This allows for the reactivation of the nanoparticle's fluorescence after its photobleaching.

Proposal for reversing the weak measurement with arbitrary maximum photon number

We present a proposal for reversing the weak (partial-collapse) quantum measurement on a cavity field with arbitrary maximum photon number. We start by putting forth a protocol to realize quantum phase gates between the cavity field and an ancilla qubit. Afterward, adopting these phase gates and some other quantum gates, we can determine the reversal of the cavity state just by observing the ancilla qubit. Compared to previous proposals, our proposal does not need any other weak measurement and can save reversal time, which is significantly important in quantum informatics and quantum computation.

Maximum photon extraction from a single quantum dot embedded in a metal/dielectric-cladded cylindrical structure

Various geometries are investigated numerically to extract the maximum number of photons to the airside from a single quantum dot embedded in a metal/dielectric cladded GaAs cylindrical structure. At the optimum cylindrical diameter, we predict that 80% of the photons can be extracted to the air side with a photon collection efficiency of 39% (68%) for a numerical aperture of 0.5 (0.8). These numbers are obtained as the influences of the internal modes and the multimode contributions are minimized at and around the target wavelength. Such geometry, by achieving good photon extraction and collection, will enhance nonclassical light generation at near infrared wavelengths.

Strong converse for the classical capacity of the pure-loss bosonic channel

This paper strengthens the interpretation and understanding of the classical capacity of the pure-loss bosonic channel, first established in [1]. In particular, we first prove that there exists a trade-off between communication rate and error probability if one imposes only a mean photon number constraint on the channel inputs. That is, if we demand that the mean number of photons at the channel input cannot be any larger than some positive number NS, then it is possible to respect this constraint with a code that operates at a rate g(ηNS/(1-p)) where p is the code error probability, η is the channel transmissivity, and g(x) is the entropy of a bosonic thermal state with mean photon number x. Then we prove that a strong converse theorem holds for the classical capacity of this channel (that such a rate-error trade-off cannot occur) if one instead demands for a maximum photon number constraint, in such a way that mostly all of the “shadow” of the average density operator for a given code is required to be on a subspace with photon number no larger than nNS, so that the shadow outside this subspace vanishes as the number n of channel uses becomes large. Finally, we prove that a small modification of the well-known coherent-state coding scheme meets this more demanding constraint.

Strong converse rates for classical communication over thermal and additive noise bosonic channels

We prove that several known upper bounds on the classical capacity of thermal and additive noise bosonic channels are actually strong converse rates. Our results strengthen the interpretation of these upper bounds, in the sense that we now know that the probability of correctly decoding a classical message rapidly converges to 0 in the limit of many channel uses if the communication rate exceeds these upper bounds. In order for these theorems to hold, we need to impose a maximum photon number constraint on the states input to the channel (the strong converse property need not hold if there is only a mean photon number constraint). Our first theorem demonstrates that Koenig and Smith's upper bound on the classical capacity of the thermal bosonic channel is a strong converse rate, and we prove this result by utilizing the structural decomposition of a thermal channel into a pure-loss channel followed by an amplifier channel. Our second theorem demonstrates that Giovannetti et al.'s upper bound on the classical capacity of a thermal bosonic channel corresponds to a strong converse rate, and we prove this result by relating the success probability to the rate, the effective dimension of the output space, and the purity of the channel as measured by the R\'enyi collision entropy. Finally, we use similar techniques to prove that similar previously known upper bounds on the classical capacity of an additive noise bosonic channel correspond to strong converse rates.

Myopic aberrations: impact of centroiding noise inHartmannShack wavefront sensing

The presence of photon noise and readout noise can lead to centroiding errors in a Hartmann Shack wavefront sensor (HS) and hence limit the accuracy of wavefront reconstruction. The aim of this paper is to compare, via Monte Carlo simulations, the accuracy of various centroiding methods in detecting noisy focal spot patterns of the HS while sensing ocular aberrations of myopic eyes. Myopic ocular aberrations were randomly simulated by using the modal statistics obtained from the measurements of 41 myopic subjects. HS spot patterns were simulated using a fast Fourier method where photon noise and readout noise were added using appropriate statistics. Adopting five different centroiding techniques: (1) centre of gravity, (2) weighted centre of gravity, (3) intensity weighted centroiding, (4) iteratively weighted centre of gravity and (5) matched filter based centroiding along with a zonal based wavefront sensing approach; the wavefronts were estimated and compared, by calculating the root mean square (RMS) wavefront error, with the initially simulated wavefront. The magnitude of readout noise was varied in terms of the maximum number of photons and electrons per subaperture per frame. The RMS error was calculated for each of the centroiding algorithms. For higher magnitude of readout noise and lesser number of photons per subaperture per frame (n), matched filter, iteratively weighted centre of gravity and intensity weighted centroiding outperform centre of gravity and weighted centre of gravity methods, for an appropriately chosen focal length and subaperture pitch. The plots of RMS error as a function of 'n' show that for lower amplitude of readout noise, computationally efficient centre of gravity and intensity weighted centroiding methods can be safely adopted to obtain high enough reconstruction accuracy. Also, even at greater readout noise levels, for a large enough 'n', intensity weighted centroiding is enough to sense the aberrations with high accuracy. It is shown that the wavefront sensing accuracy depends on the size of the spots and bit resolution of the camera. Five different centroid detection methods used in a HS in the presence of photon noise and readout noise were analysed in the context of sensing ocular aberrations of myopic subjects and identify cases under which each of these methods is appropriate.

Spin-charge conversion in a multiterminal Aharonov-Casher ring coupled to precessing ferromagnets: A charge-conserving Floquet nonequilibrium Green function approach

We derive a non-perturbative solution to the Floquet-nonequilibrium Green function (Floquet-NEGF) describing open quantum systems periodically driven by an external field of arbitrary strength of frequency. By adopting the reduced-zone scheme, we obtain expressions rendering conserved charge currents for any given maximum number of photons, distinguishable from other existed Floquet-NEGF-based expressions where, less feasible, infinite number of photons needed to be taken into account to ensure the conservation. To justify our derived formalism and to investigate spin-charge conversions by spin-orbit coupling (SOC), we consider the spin-driven setups as reciprocal to the electric-driven setups in S. Souma et. al., Phys. Rev. B 70, 195346 (2004) and Phys. Rev. Lett. 94, 106602 (2005). In our setups, pure spin currents are driven by the magnetization dynamics of a precessing ferromagnetic (FM) island and then are pumped into the adjacent two- or four-terminal mesoscopic Aharonov-Casher (AC) ring of Rashba SOC where spin-charge conversions take place. Our spin-driven results show reciprocal features that excellently agree with the findings in the electric-driven setups mentioned above. We propose two types of symmetry operations, under which the AC ring Hamiltonian is invariant, to argue the relations of the pumped/converted currents in the leads within the same or between different pumping configurations. The symmetry arguments are independent of the ring width and the number of open channels in the leads, terminals, and precessing FM islands, In particular, net pure in-plane spin currents and pure spin currents can be generated in the leads for certain setups of two terminals and two precessing FM islands with the current magnitude and polarization direction tunable by the pumping configuration, gate voltage covering the two-terminal AC ring in between the FM islands.

Pressure dependence of secondary NIR scintillation in Ar and Ar/CF/sub 4/

The variation with charge gain of the total number of photons emitted per electron, in the visible and near-infrared (NIR) regions (400</spl lambda/<1000 mm), in Ar/CF/sub 4/, mixtures, is investigated for CF/sub 4/ concentrations below 15%. Measurements were performed in a uniform field configuration and results are presented for charge gains below 100, under X-ray excitation. The maximum number of photons emitted per drifting electron (0.7 and 0.2 ph/e/sup -/ for Ar/sup +/ 2% CF/sub 4/ and Ar+10% CF/sub 4/, respectively) is obtained for a charge gain G/spl sim/4. The spectral distribution of the emitted light in Ar/CF/sub 4/ mixtures is also analyzed. The pressure dependence (1-4 atm) of the secondary light output, in the visible and near infrared regions is studied as a function of the reduced electric field E/P for pure argon and Ar/CF/sub 4/ mixtures. Above the charge multiplication threshold, the maximum number of photons emitted per electron decreases by a factor of about 1.5 when the pressure increases from 1 to 2 atms.