Silicon Photomultipliers: Status and Prospects

Physics of Particles and Nuclei Letters - Explosive progress in semiconductors physics and technology over the last century has led to replacement of almost all electro-vacuum devices with their...     

The Application Potential of Silicon Photomultipliers for a Camera of a Small-Size Cherenkov Gamma-Ray Telescope for Reducing the Detection Threshold

Technical Physics - Source and noise signals in a new camera of the TAIGA-IACT Cherenkov γ-ray telescope based on silicon photomultipliers (SiPM) have been simulated. It is shown that...     

Temperature Dependence of the Sensitivity of Silicon Photomultipliers in the Regime of Single-Photon Detection of Ultraviolet Radiation

Technical Physics - The temperature dependences of the dark count and efficiency of single-photon detection for two silicon avalanche photodetectors of ultraviolet radiation (OnSemi/SensL...     

Black Holes and Photons with Entropic Force

We study the entropic force effects on black holes and photons. It is found that application of an entropic analysis restricts the radial change △R of a black hole of radius RH, due to a test particle of a Schwarzschild radius Rn moving towards the black hole by △x near a black body surface, to be given by a relation RH△R = Rh△x/2, or △ R/λM = △x /2λm. We suggest a new rule regarding entropy changes in different dimensions, △S = 2πkD △l/λ, which unifies Verlinde＇s conjecture and the black hole entropy formula. We also propose the extension of the entropic force idea to massless particles such as photons. It is realized that there is an entropic force on a photon of energy Eγ with F = GM（Eγ/c^2）/R^2, and therefore the photon has an effective gravitational mass mγ= Eγ/c^2.     

Generating Entangled State of Photons with Beam Splitter

We demonstrate how to generate entangled state of photons with beam splitter. Its shown that we can generate entangled state by adjusting appropriately the reflectivity, the phase difference and choosing the initial state.     

Interaction of Photons with Electrons in Dielectric Media

The question of the field energy-momentum tensor in a medium is not new and many workers, in the past, attempted to find the answer to it. Nevertheless, there was no general agreement about the form of such a tensor, thus resulting in a confusion involving the very fundaments of physics. Although the present work uses well established theories, the underlying philosophy is completely novel. Investigations are mainly centered around the collisionless plasma as, in that state, development of the argument is most transparent. On the basis of a simple theoretical reasoning, it is, first of all, postulated that the momentum of the photon in a plasma is given by the Minkowski expression. This hypothesis becomes more viable as it directly leads to the accepted form for the field energy density. Furthermore, utilizing the concepts of stimulated and spontaneous emission and absorption, it is confirmed that, in the equilibrium (between radiation and plasma), the transferred momentum has the value given by the Minkowski theory. However, as will be seen, this result is valid only in the region of high frequencies. Put otherwise, when conditions are such that the laws of geometrical optics apply, the momentum of the photon is, to a good approximation, given by the Minkowski theory. In order to arrive at a more general result, valid in the domain of wave optics, a similarity between the dispersion relation (describing the wave propagation through a medium) and the relativistic energy-momentum of a particle moving through vacuum, is explored. Accepting the equivalence of these two relations implies that some of the properties of radiation in a medium, can also be described by a massive particle travelling through empty space. In other words, the task of analysing the behaviour of electromagnetic waves in a medium, can be replaced by the analysis of the free neutral vector meson field. Adoption of this equivalence results in the field energy-momentum tensor being symmetrical. A thorough study of the field theory then provides the basis for interpreting the Abraham tensor as the sum of the “orbital” and “spin” tensors. The former is directly connected with the energy transport, whereas the latter one is not. Realising that the magnitude of the spin term increases towards the lower end of the frequency spectrum provides the resolution of the Abraham-Minkowski dilemma: the energy-momentum tensor, corresponding to the electromagnetic wave in a medium, is that given by Abraham, while the one of Minkowski is only an approximation valid at high frequencies. Although this conclusion stems from studies involving collisionless isotropic plasma, it is in excellent agreement with the experimental data.     

Cherenkov interaction of vortices with a free surface

The interaction of vortex filaments in an ideal incompressible fluid with the free surface of the latter is investigated in the canonical formalism. A Hamiltonian formulation of the equations of motion is given in terms of both canonical and noncanonical Poisson brackets. The relationship between these two approaches is analyzed. The Lagrangian of the system and the Poisson brackets are obtained in terms of vortex lines, making it possible to study the dynamics of thin vortex filaments with allowance for finite thickness of the filaments. For two-dimensional flows exact equations of motion describing the interaction of point vortices and surface waves are derived by transformation to conformal variables. Asymptotic steady-state solutions are found for a vortex moving at a velocity lower than the minimum phase velocity of surface waves. It is found that discrete coupled states of surface waves above a vortex are possible by virtue of the inhomogeneous Doppler effect. At velocities higher than the minimum phase velocity the buoyant rise of a vortex as a result of Cherenkov radiation is described in the semiclassical limit. The instability of a vortex filament against three-dimensional kink perturbations due to interaction with the “image” vortex is demonstrated. Zh. éksp. Teor. Fiz. 115, 894–919 (March 1999)     

光子的双波描述

用双波理论描述光子,使光子成为具有定域性的量子粒子.光子的波粒二象性以及圆极化和线极化的二象性在理论中都得到了体现.     

Efficient Three-Party Quantum Secret Sharing with Single Photons

A scheme for three-party quantum secret sharing of a private key is presented with single photons. The agent Bob first prepares a sequence of single photons with two biased bases and then sends them to the boss Alice who checks the security of the transmission with measurements and produces some decoy photons by rearranging the orders of some sample photons. Alice encodes her bits with two unitary operations on the photons and then sends them to the other agent. The security of this scheme is equivalent to that in the modified Bennett Brassard 1984 quantum key distribution protocol. Moreover, each photon can carry one bit of the private key and the intrinsic efficiency for qubits and the total efficiency both approach the maximal value 100% when the number of the bits in the key is very large.     

Powerful Cherenkov oscillators with 2D distributed feedback

The feasibility of using 2D distributed feedback based on 2D planar and coaxial Bragg structures for generating spatially coherent radiation from rectilinear ribbon and tubular electron beams is studied. One-section and sectional Cherenkov masers are analyzed. In the former design, a 2D Bragg structure acts as a resonator and a periodic slow-wave system simultaneously. In the latter (sectional) design, radiation is synchronized in a 2D Bragg structure that is placed at the cathode end of the interaction space and couples longitudinal and transverse (azimuthal) wave flows. The wave is amplified by the electron beam mainly in the fairly long middle section. The output (collector) part contains a standard 1D Bragg structure that partially reflects the amplified radiation toward the cathode and closes the feedback circuit. It is shown that dissipation introduced into the 2D Bragg structure of the sectional design makes it possible to increase one of the transverse sizes of the system to ∼10³ wavelengths with the energy exchange efficiency and one-frequency masing mode stability remaining the same. With such an overdimension, the millimeter-wave radiation integral power may reach a gigawatt level.     

Dielectric Cherenkov masers as powerful amplifiers with superwidebandwidth

Here, we explore an important feature of dielectric Cherenkov masers (DCM's) that distinguishes them from other relativistic microwave devices. Most previous DCM experiments were carried out with rather thin dielectric liners or films. In this paper we show, however, that when the coefficient of waveguide filling with dielectric is not small, the beam-wave coupling doesn't depend on frequency, and, hence, superwide bandwidth is possible. The value of bandwidth is also determined by the current and velocity of the electron beam. DCM dispersion relations are examined both analytically, in the simplest model of total waveguide filling, and numerically, for a hollow beam in a waveguide with a dielectric liner. We show that a maximum value of bandwidth is achieved at a certain optimal value of the beam current for fixed velocity (and vice versa). Numerical results demonstrate a -3 db bandwidth of 40-50% at a peak gain of 40 dB for electron energies of 300-600 keV and beam currents of 1-10 kA     

具有变态光子带隙结构的相对论Cherenkov辐射源的研究

提出了一种变态光子带隙结构,研究了由这种结构构成的周期慢波系统的Cherenkov辐射源的特性. 利用高频仿真软件以及三维粒子模拟软件对变态及常态光子带隙慢波系统中类TM₀₁模的色散特性及注-波互作用物理过程进行了模拟研究. 结果表明,在变态光子带隙慢波系统中,类TM₀₁模纵向场分量沿角向分布均匀性得到明显改善,能有效抑制非对称模式,提高输出频谱纯度及注-波互作用效率. 关键词： Cherenkov辐射源 变态光子带隙结构 慢波系统 三维粒子模拟     

Nonlinear analysis of Cherenkov free-electron laser with double-slab structure

A compact Cherenkov free-electron laser is studied for a double-slab structure with no incident field or electromagnetic feedback mechanism. The simplified model is composed of a rectangular wave-guide partially filled with two lined parallel dielectric slabs and a sheet electron beam. The interaction between the electron beam and the electromagnetic mode is described with the macro-particle approach. The coupled equations are derived and solved numerically with the parameters of an ongoing experiment, demonstrating the amplification of emitted power from spontaneous emission.     

Propagation of Photons in Spacetime

A quantum field theory QED formalism is systematically developed to describe photon propagation in spacetime as a time evolution process based on the actual physical process of propagation between emitters and detectors as applied to the reflection of photons. This development, as well as early studies by Feynman, clearly show that a practical, computational and predictive dynamical formalism in spacetime was lacking. The present one generalizes to different experimental situations and other interacting field theories as well emphasizing the practicality of the problem treated here.     

The First-Quantized Theory of Photons

In near-field optics and optical tunnelling theory, photon wave mechanics, i.e. the first-quantized theory of photons, allows us to address the spatial field localization problem in a flexible manner which links smoothly to classical electromagnetics. We develop photon wave mechanics in a rigorous and unified way, based on which field quantization is obtained in a new way.     

Quantum Secure Direct Communication with Authentication Expansion UsingSingle Photons

In this paper we propose two quantum secure direct communication (QSDC) protocols with authentication. The authentication key expansion method is introduced to improve the life of the keys with security. In the first scheme, the third party, called Trent is introduced to authenticate the users that participate in the communication. He sends the polarized photons in blocks toauthenticate communication parties Alice and Bob using the authentication keys. In the communication process, polarized single photons are used to serve as the carriers, which transmit the secret messages directly. The second QSDC process with authentication between two parties is also discussed.