Dynamics of two quantum entangled particles interacting with a potential barrier in an EPR experiment

The effect of a position measurement on one component of a two-particle wave packet in a regularized space-momentum entangled state is analyzed. The wave packet interacts in the physical space with a potential barrier. When a position or momentum measurement is performed on one particle, a consequent strong modification of the dynamics of the other particle occurs.     

Vibration of a continuous beam with multiple elastic supports excited by a moving two-axle system with separation

This paper studies the dynamics of a two-axle system travelling along a continuous elastic beam resting on elastic supports modelled as linear springs. During its travel along the vibrating beam, the vibrating two-axle system may separate from the beam for certain time intervals when there is no interaction between the two-axle system and the beam. As a result, the dynamics of the whole system can be very different from the case when separation is ignored. The study is focused on conditions that facilitate the onset of separation between the moving and supporting structures and subsequent possible reattachment. Numerical results show that the occurrence of separation may be influenced to a large extent by the presence of intermediate elastic supports.     

Thin position for knots and 3-manifolds

We prove that for 2-bridge knots and 3-bridge knots in thin position the double branched cover inherits a manifold decomposition in thin position. We also argue that one should not expect this sort of correspondence to hold in general.     

New designs and characteristics analysis of non-polarizing beam splitters

When used at oblique angles of incidence, the reflectance and transmittance of thin films exhibit strong polarization effects, particularly for the films inside a glass cube, which results from the fact that the tangential components of the electric and magnetic fields are continuous across each layer interface. However, for many applications, the polarization effects are undesirable and should be reduced. In the present paper, a method for designing a non-polarizing beam splitter (NPBS) in a cube is introduced, based on the Brewster condition. Applied examples of the NPBSs designed employing this method are also researched within specified wavelength ranges. Moreover, the effects of some important parameters, including the incident angle and the material indices, on the NPBS are investigated. Optical property simulations are presented.     

皮秒扫描相机在加速器研究中的应用──监测电子束团的纵向分布

本文描述了一台基于皮秒扫描机机的电子束团纵向分布(电子束团长度)测试系统,报道了应用这套系统在中科院高能物理所北京自由电子激光装置(BFFL)S波段射频直线加速器、正负电子对撞机(BEPC)和中国原子能科学研究院L波段注入器(LBINJ)上开展的测量工作.     

Analysis and modelling of high power laser beam position sensing

A new theory using a rotating convex mirror to reflect part of a laser beam into a pyro-electric sensor in order to detect the high power laser beam position is addressed in this research. The experiments were performed on the Nd: YAG laser system. The sensing performance was tested with the average power up to 50 W, duration time 1 ms and duration frequency 360 Hz. The results of static experiments show that the sensing system designed and developed in this research may correctly detect the Nd: YAG laser beam with the system parameters varied. The results of dynamic experiments show that the average sensing accuracy of beam position is up to 90% with a wide variation of laser system parameters.     

Optimize design super collimation in square lattice two-dimensional photonic crystals

The plane wave expansion (PWE) method was used to get the three-dimensional band diagram and equifrequency surface (EFS). From the EFS the maximum flatness half width (MFHW) and its position were got. The relation between MFHW and filling fraction P_f, dielectric ratio ε_b/ε_a were given in order to get the optimal structure we employ in this paper. Then the maximum super collimation was given by beam propagation method (BPM).     

Measurement of avalanche size and position resolution of RPCs with different surface resistivities of the high voltage provider

The effects of surface resistivity of the high voltage provider on the space dispersion of the induced charge of a prototype Resistive Plate Chamber (RPC) have been studied experimentally and theoretically. The results of both experiment and theory agree and confirm that a two-Gaussian function can be used to fit the dispersion of the induced charge of the RPC. It is shown that the Gaussian function with the narrower width is mainly due to the expansion of the avalanche charge in the gas gap of the RPC, and the Gaussian function with the larger width is due to the charge dispersion when it passes through the resistive carbon film. This will be useful in the RPC design when one wants to make an RPC with high position resolution.     

Approximating ideal diffractive optical systems

In numerical wave optics involving diffractive optical elements one is required, at some point, to form a multiplicative matrix factorization. This paper is concerned with such representations and related approximations of ideal diffractive optical systems. Various simple diffractive optical elements are used. The basic factoring problem being highly nonlinear, a minor parallelism in terms of beam splitters and beam combiners makes the task computationally much more tractable and versatile. This gives rise to several matrix nearness problems of geometric nature.