Unified approach to superposition states of the quantized radiation field

Summary In the recent years various and interesting superposition states of the quantized radiation field were investigated in the literature, such as that involving two number states by Wodkiewiczet al.; that involving two coherent states by Hillery and Gerryet al.; that involving two squeezed states by Xinet al., etc. Here we study a general one-parameter superposition state which unifies those states and others in the literature, all becoming a particularization of ours. General expressions characterizing the physical properties of the field are obtained. The role played by the present superposition state as an alternative interpolating state is also discussed. The authors of this paper have agreed to not receive the proofs for correction.     

钾原子的能量积聚诱导电离和双光子共振三光子电离

用染料激光激发钾蒸气 ,发现了钾原子的两种电离机制和三个电离通道 :能量积聚诱导的电离 ,4S 6S和4S 4D双光子共振三光子电离。对前两个电离通道 ,分别研究了电离谱与钾蒸气温度和激光强度的关系 ,发现了钾原子的辐射囚禁效应和钾原子电离的非线性现象 ,并给出了定性解释     

Temporal coherent control induced by wave packet interferences in one and two photon atomic transitions

The interaction of a sequence of two identical ultrashort laser pulses with an atomic system results in quantum interferences as in Ramsey fringes experiments. These interferences allow achievement of temporal coherent control of the excitation probability. We present the results of a temporal coherent control experiment on two different atomic systems: one-photon absorption in K (4s-4p) and two-photon absorption in Cs (6s-7d). In K, the quantum interferences between the two excitation paths associated with the laser pulses are revealed through rapid oscillations of the excitation probability as a function of the time delay between the two pulses. These oscillations take place at the transition frequency (period T = 2.56 fs). The interferences are modulated by beats (at about 580 fs) resulting from the doublet structure of the excited state (4p (² P _1/2 , ² P _3/2 )). Three complementary interpretations of this experiment are presented: in terms of beats of quantum interferences, of variation in the spectrum intensity, and of wave packet interferences. Whenever the two laser pulses are temporally overlapped, optical interferences are superimposed on to the quantum interferences. The distinction between these two types of interference is clearly revealed in the two-photon excitation scheme performed on Cs (6s-7d (² D _3/2 , ² D _5/2 )) because quantum interferences occur at twice the frequency of the optical interferences. Received: 30 December 1997 / Revised: 28 February 1998 / Accepted: 4 March 1998     

强作用介质诱导的光子辐射和双轻子产生

考察了相对论性高能重离子碰撞中产生的硬部分子喷注穿过强作用介质时,喷注与介质中的部分子多次散射诱导的光子辐射与双轻子产生,得到了对应于opacity展开第一阶的光子横动量谱,辐射光子导致的喷注的能量损失以及双轻子的不变质量谱,结果表明,光子的产生率随横动量的增加而降低,双轻子的产生率随其不变质量的增加而减小,辐射光子导致的能量损失线性依赖强作用介质靶的厚度。     

利用光子统计概率测量单分子光子源的信号背景比

理论上研究了基于Hanbury Brown Twiss 探测方式，利用单光子和双光子统计概率P RS(1),PRS(2),直接测量单分子光子源的信号背景比.在研究过程中同时考 虑到单分子布居于暂稳态和探测器量子效率对测量结果的影响.在满足PRS(1)2 PRS(2)-3PRS(2)的条件时，研究给出了一种有效测量信号背景比的方 法SBR=P2RS(1)/2PRS(2).另外，分析讨论了Mandel参数Q 与信号背景比之间的关系. 关键词： 单分子光子源 信号背景比 光子统计 暂稳态 Mandel参数     

光子图像统计处理

讨论了一种对有限光子图像累加的统计处理方法。在超微弱发光的研究中（例如细胞的超微弱光），由于发光强度较弱，需要用像增强器对超微弱发光图像进行增强得到可视光子图像，超微弱发光的光子图像不可避免地受到像增强系统暗噪声及背景噪声的影响，使光子图像湮没在噪声中。为从原始图像中检验出信号，常将采集到的有限光子图像进行累加以增加样本数，根据信号光子和噪声光子的不同统计分布，运用似然比检验方法得到有效判断累加图像中某像素是否含有信号光子，由此剔除图像中的噪声光子，得到信噪比改善的光子图像。     

钠原子分子中的共振多光子电离谱的研究

在钠蒸气中，分别通过原子和分子的双光子共振三光子电离和双光子混合共振三光子电离两种激发机制，测得了不同温度下的电离信号激发谱，对结果作了较为详细的分析。     

Optical Storage Media with Dye-Doped Minute Spheres on Polymer Films

We have fabricated a new optical storage media using minute spheres arranged on a surface relief grating (SRG). Using minute spheres as recording bits, we can limit recordable regions by sphere size, and can realize high resolution reproduction in the plane direction. Surface relief structures were made on a polymer thin film on which we performed diffusion arrangement and adsorptive fixation of minute spheres. The stability of the arranged spheres was confirmed for heating and washing. Furthermore, we used a dipping method for a more simple arrangement of minute spheres on a large area of the substrate and made a monolayer sample of the spheres. We were able to realize a highly sensitive reconstruction of the medium using a confocal optical system as a record and readout system.