Influence of Photon Mass on Vacuum Birefringence Experiment

Influence of photon mass on vacuum birefringence experiment is analysed according to the nonlinearities of vacuum quantum electrodynamics for the light propagation through an intense electromagnetic field. It is shown that although the photon mass will cause a change of the refractive indices n┴ and nⅡ of vacuum birefringence, the difference nⅡ - n┴ is unchanged, which means that the effect of photon mass cannot be observed in vacuum birefringence experiment.     

e~+/e~- discrimination in liquid scintillator and its usage to suppress ~8He/~9Li backgrounds

Reactor neutrino experiments build large-scale detector systems to detect neutrinos. In liquid scintillator,a neutral bound state of a positron and an electron, named positronium, can be formed. The spin triplet state is called ortho-positronium(o-Ps). In this article, an experiment is designed to measure the lifetime of o-Ps, giving a result of 3.1 ns. A PSD parameter based on photon emission time distribution(PETD) was constructed to discriminate e~+/e~-. Finally, the application of e~+/e~- discrimination in the JUNO experiment is shown. It helps suppress ~8He/~9Li backgrounds and improves the sensitivity by 0.6 in χ~2 analysis with an assumption of σ=1 ns PMT Transit Time Spread, which will bring a smearing effect to the PETD.     

CLAS＋FROST： new generation of photoproduction experiments at Jefferson Lab.

A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer （CLAS） and availability of circularly and linearly polarized tagged photon beams provide unique conditions for this type of experiments. Recent addition of the Frozen Spin Target （FROST） gives a remarkable opportunity to measure double and triple polarization observables for different pseudo-scalar meson photopro- duction processes. For the first time, a complete or nearly complete experiment becomes possible and will allow model independent extraction of the reaction amplitude. An overview of the experiment and its current status is presented.     

Lattice Boltzmann Model and Geophysical Hydrodynamic Equation

A lattice Boltzmann equation model in a rotating system is developed by introducing the Coriolis force effect.The geophysical hydrodynamic equation can be derived from this model.Numerical computations are performed to simulate the cylindrical annulus experiment and Benard convection.The numerical results have shown the flow behaviour of large-scale geostrophic current and Benard convection cells,which verifies the applicability of this model to both theory and experiment.     

Investigation on dependence of BiFeO3 dielectric property on oxygen content

The influence of oxygen content on the dielectric property of BiFeO3 ceramics is studied by experiment and firstprinciples calculation.The experimental result demonstrates that the dielectric constant of BiFeO3 is strongly dependent on introduced oxygen and oxygen vacancies.By comparison with BiFeO3,the introduced oxygen and oxygen vacancies can lead to a reduction in dielectric constant of BiFeO δ at a lower frequency.The first-principles calculation also shows a similar result when photon energy is in a range of 2.0-4.1 eV.A likely explanation is that this oxygen content dependence may be ascribed to the distortion of Fe-O octahedron structure due to oxygen vacancies or excess oxygen ions in the crystal structure of BiFeO3.     

Photon motion and weak gravitational lensing in black-bounce spacetime

The effect of spacetime curvature on photon motion may offer an opportunity to propose new tests on gravity theories.In this study,we investigate and focus on the massless(photon) particle motion around blackbounce gravity.We analyze the horizon structure around a gravitational compact object described by black-bounce spacetime.The photon motion and the effect of gravitational weak lensing in vacuum and plasma are discussed,and the shadow radius of the compact object is also studied in black-bou...     

Quantum electrodynamics in a laser and the electron laser collisionQuantum electrodynamics in a laser and the electron laser collision

Quantum electrodynamics in a laser is formulated, in which the electron-laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron- laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of y-ray laser generation by use of this kind of collision is discussed.     

Repeat-until-success measurement-based scheme for controlled phase gates in a cavity

We propose a new repeat-until-success （RUS） measurement-based scheme to implement quantum controlled phase gates according to the effect of dipole-induced-transparency （DIT） in a cavity and single-photon interference at a 50：50 beam-splitter. In our scheme, the DIT effect can appropriately attach a photon to the state of the dipoles according to their initial state, and in this way, a suitably encoded dipole-photon state is thus prepared. The measurement of the photon after it passing through a 50：50 beam-splitter can project the encoded matter-photon state to either a desired phase gate operation for the matter qubits or to their initial states. The recurrence of the initial state permits us to implement the desired entangling gate in a RUS way.     

Quantum electrodynamics in a laser and the electron laser collision

Quantum electrodynamics in a laser is formulated, in which the electron–laser interaction is exactly considered, while the interaction of an electron and a single photon is considered by perturbation. The formulation is applied to the electron– laser collisions. The effect of coherence between photons in the laser is therefore fully considered in these collisions. The possibility of γ-ray laser generation by use of this kind of collision is discussed.     

The mechanism of producing energy-polarization entangled photon pairs in the cavity-quantum electrodynamics scheme

We investigate theoretically two photon entanglement processes in a photonic-crystal cavity embedding a quantum dot in the strong-coupling regime. The model proposed by Johne et al. (Johne R, Gippius N A, Pavlovic G, Solnyshkov D D, Shelykh I A and Malpuech G 2008 Phys. Rev. Lett. 100 240404), and by Robert et al. (Robert J, Gippius N A and Malpuech G 2009 Phys. Rev. B 79 155317) is modified by considering irreversible dissipation and incoherent continuous pumping for the quantum dot, which is necessary to connect the realistic experiment. The dynamics of the system is analysed by employing the Born–Markov master equation, through which the spectra for the system are computed as a function of various parameters. By means of this analysis the photon-reabsorption process in the strong-coupling regime is first observed and analysed from the perspective of radiation spectrum and the optimal parameters for observing energy-entangled photon pairs are identified.     

Vacuum Polarization of Twisted Scalars in a Non—simply Connected Space—time and Its Effects

The vacuum polarization due to twisted scalar fields is investigated in a non-simply connected space-time,It is found that some photon modes acpuire an imaginary topological mass,thus travelling at a superluminal speed.Topological bi-refringence is expected for photons propagating perpendicularly to the compactification direction.The effect of a topological photom mass on the static properties of electromagnetic fields is also considered for the cases of both twisted and untwisted scalar fields,Our result shows that in the untwisted case the magnetic field is screened along the radial dirction for massive photon modes.while in the twisted case no screening occurs and the magnetic fields merely oscillate.     

Two narrow bandwidth photons interfering in an electromagnetically induced transparency （EIT） system

In this paper, we have analysed in detail the quantum interference of the degenerate narrowband two-photon state by using a Mach-Zehnder interferometer, in which an electromagnetically induced transparency （EIT） medium is placed in one of two interfering beams. Our results clearly show that it is possible to coherently keep the quantum state at a single photon level in the EIT process, especially when the transparent window of the EIT medium is much larger than the bandwidth of the single photon. This shows that the EIT medium is possibly a kind of memory or repeater for the narrowband photons in the areas of quantum communication and quantum computer. This kind of experiment is feasible within the current technology.     

Suppression of the emittance growth induced by coherent synchrotron radiation in triple-bend achromats

The coherent synchrotron radiation (CSR) effect in a bending path plays an important role in transverse emittance dilution in high-brightness light sources and linear colliders, where the electron beams are of short bunch length and high peak current. Suppression of the emittance growth induced by CSR is critical to preserve the beam quality and help improve the machine performance. It has been shown that the CSR effect in a double-bend achromat (DBA) can be analyzed with the two-dimensional point-kick analysis method. In this paper, this method is applied to analyze the CSR effect in a triple-bend achromat (TBA) with symmetric layout, which is commonly used in the optics designs of energy recovery linacs (ERLs). A condition of cancelling the CSR linear effect in such a TBA is obtained, and is verified through numerical simulations. It is demonstrated that emittance preservation can be achieved with this condition, and to a large extent, has a high tolerance to the fluctuation of the initial transverse phase space distribution of the beam.     

Quantum Logic Network for Cloning a State Near a Given One Based on Cavity QED

A quantum logic network is constructed to simulate a cloning machine which copies states near a given one. Meanwhile, a scheme for implementing this cloning network based on the technique of cavity quantum electrodynamics （QED） is presented. It is easy to implement this network of cloning machine in the framework of cavity QED and feasible in the experiment.     

Quantum phase transitions of fermionic atoms in an anisotropic triangular optical lattice

The effect of anisotropy caused by a confining potential on the properties of fermionic cold atoms in a triangular optical lattice is systematically investigated by using the dynamical cluster approximation combined with the continuous time quantum Monte–Carlo algorithm.The quantum phase diagrams which reflect the temperature–interaction relation and the competition between the anisotropic parameter and the interaction are presented with full consideration of the anisotropy of the system.Our results show that the system undergoes a transition from Fermi liquid to Mott insulator when the repulsive interaction reaches a critical value.The Kondo effect also can be observed in this system and the pseudogap is suppressed at low temperatures due to the Kondo effect.A feasible experiment protocol to observe these phenomena in an anisotropic triangular optical lattice with cold atoms is proposed,in which the hopping terms are closely related to the lattice confining potential and the atomic interaction can be adjusted via the Feshbach resonance.     

Ion Photon Emission Microscope for Single Event Effect Testing in CIAE

Ion photon emission microscopy(IPEM) is a new ion-induced emission microscopy. It employs a broad ion beam with high energy and low fluence rate impinging on a sample. The position of a single ion is detected by an optical system with objective lens, prism, microscope tube and charge coupled device(CCD). A thin ZnS lilm doped with Ag ions is used as a luminescent material. Generation efficiency and transmission efficiency of photons in the ZnS(Ag) film created by irradiated Cl ions are calculated. A single Cl ion optical microscopic image is observed by high quantum efficiency CCD. The resolution of a single Cl ion given in this IPEM system is 6μm. Several factors influencing the resolution are discussed. A silicon diode is used to collect the electrical signals caused by the incident ions. Effective and accidental coincidence of optical images and electronic signals are illustrated. A two-dimensional map of single event effect is drawn out according to the data of effective coincidence.     

Effect of Invariant Transformation in One-Dimensional Randomly-Perturbed Photonic Crystal

An effect of invariant transformation in one-dimensional randomly perturbed photonic crystals is presented analytically and numerically. According to this effect, localization length can be investigated in different identical intervals, and the relations among these zones are governed by a simple expression. A concept of effective randomness is introduced as a result, which denotes the disorder of phase shifts actually. The divergent behaviour of localization length in the limit of low frequency can be interpreted directly through this effect. Since the effect is obtained without any approximation, it is expected to be useful in understanding the general intrinsic nature of one-dimensional randomly perturbed photonic crystals.     

Influences of decoherence on the generation of a macroscopic superposition state using weak cross-Kerr effect

Considering a system in which a single photon and a coherent field propagate through a Kerr medium, when the weak cross-Kerr interaction between the coherent state and the single photon under decoherence is involved, this paper derives analytically a macroscopic superposition state by the superoperator method and investigates the influences of decoherence on the coherence properties of the obtained state. It finds that the macroscopic superposition state will experience evolution from a pure superposltion state to a mixed state in a dissipative environment and the Kerr effect makes the field display a periodic revival from decoherence for a short time.     

Monte Carlo simulation of photon migration path in turbid media

A new method of Monte Carlo simulation is developed to simulate the photon migration path in a scattering medium after an ultrashort-pulse laser beam comes into the medium.The most probable trajectory of photons at an instant can be obtained with this method.How the photon migration paths are affected by the optical parameters of the scattering medium is analyzed.It is also concluded that the absorption coefficient has no effect on the most probable trajectory of photons.     

Spatial Interference Effect of Two—Photon in Femtosecond—Pules Pumped Spontaneous Parametric Down—Conversion

We have used the transverse correlated properties of the entangled photon pairs generated in the process of spontaneous parametric down-conversion,which is pumped by a femtosecond pulse laser,to perform Young‘s interference experiment.Unlike the case of a continuous wave laser pump,a broadband pulse laser pump can submerge an interference pattern.In order to obtain a high visibility interference pattern,we used a lens with a tunable focal length and two interference filters to eliminate the effects of the broadband pump laser.It is proven that the process of two-photon direct interference is a post-selection process.