Influence of Cavity Decay on Phase Distribution and Rabi Flopping in Cavity QED

The quantum mechanical phase distribution and the quantum oscillations of population are studied for a cavity field togetherwith a driven classical field. The atom is sent through the cavity and driven by a classical field. Also the time evolution of the system including decay is obtained. The graph showing the Rabi oscillations for this system is changed into a bit pattern from the system without decay. The phase probability function is also affected due to the presence of cavity decay.     

Optimization of Circular Ring Microstrip Antenna Using Genetic Algorithm

Circular ring microstrip antennas have several interesting properties that make it attractive in wireless applications. Although several analysis techniques such as cavity model, generalized transmission line model, Fourier-Hankel transform domain and the method of matched asymptotic expansion have been studied by researchers, there is no efficient design tool that has been incorporated with a suitable optimization algorithm. In this paper, the cavity model analysis along with the genetic optimization algorithm is presented for the design of circular ring microstrip antennas. The method studied here is based on the well-known cavity model and the optimization of the dimensions and feed point location of the circular ring antenna is performed via the genetic optimization algorithm, to achieve an acceptable antenna operation around a desired resonance frequency. The antennas designed by this efficient design procedure were realized experimentally, and the results are compared. In addition, these results are also compared to the results obtained by the commercial electromagnetic simulation tool, the FEM based software, HFSS by ANSOFT.     

A High-Efficiency Second-Harmonic Gyrotron with a Depressed Collector

The gyrotron with an electrically insulated collector has been manufactured and tested. The 60% output efficiency is obtained for the Collector Potential Depression (CPD) operation regime. The results of the numerical simulation of the electron energy spectrum in the collector region of the second-harmonic technological 24 GHz gyrotron are presented. It is shown, that the minimal electron beam energy is about 20% of the initial value and that the gyrotron cavity should be expanded to achieve the highest output efficiency of the gyrotron with energy recovery. The highest experimental decelerating voltage is in good agreement with the calculation of the electron energy spectrum.     

193 nm photolysis of CHCl3: Probe of the CH product by CRDS

The CH radical production induced by 193 nm two-photon photolysis of CHCl₃ has been measured for the first time via the cavity ring-down absorption spectroscopy of its A–X bands, using a commercial nanosecond pulsed dye laser. The range of pressure and laser intensity, as well as the time window detection, have been carefully chosen to ensure a constant CH number density during the measurement and to avoid post-photolysis reactivity. Internal energy distribution of the CH(X²II) fragment has been derived from population distribution simulations, leading to an average vibrational temperature T_vib = 1900 ± 50 K and rotational temperature T_rot = 300 ± 20 K. Two competing mechanisms can be invoked for the CH production channel: either two-photon absorption via resonant excited states of CHCl₃ leading to dissociation of excited CHCl₃, or two-photon sequential dissociation via the formation of the vibrationally excited CHCl₂ fragment. The latter mechanism is proposed to be the prominent process for CH formation.     

Spatial and temporal probing of a laser-induced plasma plume by cavity ringdown spectroscopy

The laser-induced plasma plume of a Ti target in vacuum is probed by the technique of cavity ringdown spectroscopy. A model is developed to perform a forward convolution of atomic absorption line profile measurements. The model accounts for laser-induced plasma characteristics such as anisotropy of the plume and velocity distributions of the ablated particles as well as of the cavity ringdown features such as geometry and time selectivity. The absorption lineshapes of atomic transitions are calculated and discussed for given sets of parameters. Calculated line profiles are fitted to experimental line profiles obtained from nanosecond-laser ablation of the target and provide data about the plume dynamics.     

Cavity QED based tuneable,delayed-choice quantum eraser

We propose an experimentally feasible idea for the delayed-choice quantum eraser, having adjustable path distinguishability/fringe visibility. The schematics are based on resonant, dispersive and Ramsey interactions of atoms under cavity QED scenario. The option for tuneability of the fringes in a delayed-choice setup stringently marks the conception of the time in the quantum theory, operational meanings of the state vector reduction and raises questions about Ψ$\Psi$-ontic models while helping to shed out the controversies surrounding the quantum eraser theme. The proposal can be efficiently executed experimentally within the prevailing cavity QED experimental research scenario with good overall success probability and fidelity.     

基于腔体滤波器的可调谐微波开关的设计

为了满足无人机数据链路测试中信号转换的需求,提出一种可调谐的S波段分波道微波转换开关设计方案,其中采用开关控制电路对输入微波信号进行分波道选择,两路加载集总电容的三阶方杆梳状腔体滤波器对微波信号进行选频、滤波,同时可通过调节调谐螺钉实现两波道中心谐振频点同频或异频,调谐中心频率范围可达20 MHz,自由度较高;微波开关经参数仿真结果满足设计要求,研制完成的微波开关经过实际测试和应用验证,各项技术指标满足使用要求,同时该微波转换开关具有大功率、低损耗、高隔离度等优点,性能稳定、自由度高、易于实现,可满足无人机数据链测试诊断的信号转接要求。     

The Invariant and Quasi-invariant Transformations of the Stable Lévy Processes

Let ξ(t),t∈[0,1] be a strictly stable Lévy process with the index of stability α∈(0,2). By ℘ _ξ we denote the law of ξ in the Skorokhod space . For arbitrary ξ we construct ℘ _ξ -quasi-invariant semigroup of transformations of . Under some nondegeneracy condition on the spectral measure of the stable process we construct ℘ _ξ -quasi-invariant group of transformations of . In symmetric case this group is a group of the invariant transformations.      

双隔离泡H021模腔的谐振频率及Q值

本文计算了双隔离泡H₀₂₁模腔的谐振频率及品质因子.利用泡壁的对称性,得到腔中电介质分布具有轴对称性,泡上、下底的影响用微扰给出了腔谱振频率和品质因子的变化.     

Q-matrix recognition via secondary and universal polytopes

T (Mx+q)=0, Mx+q≥0, x≥0 has a solution. We explain how one can use the polyhedral structure of the set of all triangulations of a finite point set to determine if an n×n matrix M is a Q-matrix. Our implementation of the algorithm is practical for deciding the Q-nature for all M with n≤8. Received May 30, 1997 / Revised version received June 12, 1998 Published online November 24, 1998