Production of χc and ηc in Ultra-Peripheral Collisions with Two-Photon Processes

We calculate the production of χc and ηc by the two-photon process in ultra-peripheral heavy ion collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies. The differential cross section of transverse momentum distribution and rapidity distribution for (H = χc and ηc), are estimated by using the equivalent photon flux in the impact parameter space. The numerical results indicate that the study of χc and ηc in ultra-peripheral heavy ion collisions are feasible at RHIC and LHC energies.

Preparation of optimal entropy squeezing state of atomic qubit inside the cavity via two-photon process and manipulation of atomic qubit outside the cavity

Considering two atomic qubits initially in Bell states, we send one qubit into a vacuum cavity with two-photon resonance and leave the other one outside. Using quantum information entropy squeezing theory, the time evolutions of the entropy squeezing factor of the atomic qubit inside the cavity are discussed for two cases, i.e., before and after rotation and measurement of the atomic qubit outside the cavity. It is shown that the atomic qubit inside the cavity has no entropy squeezing phenomenon and is always in a decoherent state before the operating atomic qubit outside the cavity. However,the periodical entropy squeezing phenomenon emerges and the optimal entropy squeezing state can be prepared for the atomic qubit inside the cavity by adjusting the rotation angle, choosing the interaction time between the atomic qubit and the cavity, controlling the probability amplitudes of subsystem states. Its physical essence is cutting the entanglement between the atomic qubit and its environment, causing the atomic qubit inside the cavity to change from the initial decoherent state into maximum coherent superposition state, which is a possible way of recovering the coherence of a single atomic qubit in the noise environment.

The entanglement of two dipole-dipole coupled atoms interacting with a thermal field via a two-photon process

This paper studies entanglement between two dipole-dipole coupled atoms interacting with a thermal field via a two-photon process. It shows that the entanglement is dependent on the mean photon number of the thermal field and the dipole-dipole interaction. The results also show that the atom-atom entanglement through the two-photon process is larger than that through the one-photon process and a remarkable amount of entanglement between the atoms still remains at certain times even for a very highly noisy thermal field.

Entropy squeezing of a moving atom and control of noise of the quantum mechanical channel via the two-photon process

Based on the quantum information theory, we have investigated the entropy squeezing of a moving two-level atom interacting with the coherent field via the quantum mechanical channel of the two-photon process. The results are compared with those of atomic squeezing based on the Heisenberg uncertainty relation. The influences of the atomic motion and field-mode structure parameter on the atomic entropy squeezing and on the control of noise of the quantum mechanical channel via the two-photon process are examined. Our results show that the squeezed period, duration of optimal entropy squeezing of a two-level atom and the noise of the quantum mechanical channel can be controlled by appropriately choosing the atomic motion and the field-mode structure parameter, respectively. The quantum mechanical channel of two-photon process is an ideal channel for quantum information （atomic quantum state） transmission. Quantum information entropy is a remarkably accurate measure of the atomic squeezing.

Large transverse momentum dilepton production in heavy ion collisions with two-photon processes

The cold component of large transverse momentum dilepton production via semi-coherent two- photon interaction is calculated. The cold contribution is essential to the dilepton spectra in the soft region for different mass bins. The results are compared with the PHENIX experimental data at RHIC, and we find that the modification of semi-coherent two-photon processes is more evident with the rising dilepton mass bins.

双光子Tavis-Cummings模型中场的压缩性质

本文将Tavis-Cummings模型推广到双光子过程的情形,具体就两个原子与单模场相互作用时场的性质进行了研究。我们发现,只要适当制备原子对的初态,场的演化过程中就会出现压缩,并且在一定的初态下,场中还会出现高阶压缩,而此时通常意义上的压缩并不存在。

双光子J-C模型场熵的压缩特性

研究了双光子过程J-C模型场熵的压缩特性,讨论了原子初态和失谐量对场熵压缩特性的影响。

氟化物对Er^(3+)/Yb^(3+)共掺的碲酸盐玻璃上转换和红外发光性能的影响

Er3+/Yb3+共掺的碲酸盐玻璃由于其良好的上转换发光性能而得到广泛的研究。本文将氟化物引入碲酸盐玻璃中,通过熔融法制备了量比为70TeO2-(30-x)ZnO-xZnF2-0.15Er2O3-1.5Yb2O3(x=0,5,10,15,20)的碲酸盐氧氟玻璃样品,并测试其热稳定性、拉曼光谱以及受激发射光谱。实验结果表明,随着氟化物含量的提高,Er3+离子的410,555,670 nm上转换发光和2~3μm波段中红外发光得到增强,并且红光提高强度比绿光和蓝光更明显。在分析了氟离子引入后对上转换与近中红外波段发光的内在影响机制发现:碲酸盐玻璃系统中的氟化物一方面促进能量传递过程中Er3+离子的双光子吸收,促进粒子跃迁至相应的高能级;另一方面,引入氟化物后的碲酸盐玻璃的最大能量声子态密度下降也是降低无辐射跃迁概率、提高上转换和中红外发射强度的重要原因。

Kerr效应对非简并双光子Jaynes-Cummings模型腔场谱的影响

研究了含Ｋｅｒｒ介质两模双光子Ｊａｙｎｅｓ－Ｃｕｍｍｉｎｇｓ模型腔场谱，给出了初始光场为光子数态、相干态和热光场时的计算结果，讨论了Ｋｅｒｒ效应对谱结构的影响．发现一模腔场谱的频率可以被另一模初始场强灵敏地控制．

一种简便、快速的大肠杆菌质粒转化方法

将受体菌与质粒 Ｄ Ｎ Ａ 混匀直接在 Ｃａ２ ＋ 离子选择平板上进行转化和筛选， 其转化过程仅需２ｍｉｎ 左右， 并能得到１０５ 以上的转化效率， 可满足一般克隆工作的需要。

双光子Tavis－Cummings模型场熵的演化

本文研究了双光子Ｔａｖｉｓ－Ｃｕｍｍｉｎｇｓ模型场熵的演化，讨论了原子初态和初始平均光子数对场熵演化的影响。

双光子过程耦合腔系统中光场的量子特性

本文研究了双光子过程原子与耦合腔相互作用系统中腔场的压缩效应和反聚束效应.考虑系统总激发数等于2的情况,利用数值计算方法讨论了腔场间的耦合强度变化和原子与腔场间耦合强度变化对反聚束效应的影响.研究结果表明:腔场不呈现出压缩效应;腔场的反聚束效应与原子与腔场的耦合系数之间,以及与腔场间的耦合系数之间都存在着非线性关系.

压缩真空场中非简并双光子过程中系统约化密度主方程

在本文中我们利用投影算符技巧通过刘维方程推导了系统约化密度主方程，这种方法特别适合于赝非马尔可夫的库场情况。所得结果和改进的路易塞尔方法的结果一致。这种方法能正确地在各种库的情况下给出单光子过程和双光子过程的系统的主方程。

压缩真空场中系统约化密度主方程

为适应近年来人工制备库的情况，特别是简并双光子过程中，压缩真空库的广义朗之万力之双时相关函数呈现一种膺非马尔珂夫特性，我们重新定义了库的谱密度，改进了Ｌｏｕｉｓｅｌｌ推导系统约化密度主方程的方法，克服了原有方法的弱点，获得了比较满意的结果，能正确地在各种库的情况下给出单光子过程和双光子过程的系统的主方程。我们首次求得压缩真空库场中简并双光子过程的系统约化密度主方程。

简并多光子过程中两能级原子消相干性的消除

研究置于外部环境 (热库 )中的两能级原子消相干性的消除 .在相互作用系统中通过外加驱动场的方法 ,得到简并多光子过程中两能级原子约化密度算符非对角元 .当外加驱动场的演化规律满足一定的条件时 ,可使两能级原子的消相干被消除 .

双光子过程单模辐射场与二能级原子相互作用系统场熵的压缩特性

研究了双光子过程单模辐射场与二能级原子相互作用系统场熵的压缩特性 。

钠蒸气近4D能级双光子共振光谱分析

由钠蒸气近4D能级双光子共振光谱证实，存在330nm纯参量四波混频信号，共振时参量四波混频抑制了放大的自发辐射，而激光波长失谐时产生的受激超拉曼散射削弱了参量四波混频。

一种有效的上转换荧光粉Y_3O_4Br∶Er^(3+)

采用高温固相法合成了纯相的Y3O4Br∶Er3+(n(Y3+)∶n(Er3+)=1%,下同)上转换荧光粉,并用X射线衍射对其结构进行了表征.研究了在514.5 nm激光激发下Y3O4Br∶Er3+的斯托克斯发射光谱及980,785 nm激光激发下Y3O4Br∶Er3+上转换发射光谱.通过上转换发光强度对泵浦激光功率的依赖关系研究了上转换发光机制,证明了样品的绿光和红光上转换发射均是双光子过程.值得关注的是,Y3O4Br∶Er3+样品在泵浦密度约为0.33 mW/mm2(980 nm)激光的激发下,可以观察到很强的绿光发射,这表明Y3O4Br∶Er3+荧光粉是一种有效的上转换荧光粉.

含时单频双光子过程的精确解和Berry相因数

本文利用Ｌｅｗｉｓ－Ｒｉｅｓｅｎｆｅｌｄ的量子不变量理论，求出了单频双光子过程的精确解，研究了此精确解的绝热渐近极限，求出了双光子过程在量子绝热情形下的Ｂｅｒｒｙ相因数。

压缩真空态中二能级原子简并双光子过程的广义Bloch-Siegert频移

用密度算符主方程方法研究了一二能级原子与宽带压缩真空态光场的简并双光子相互作用。我们发现原子偶极矩随时间的变化与压缩真空态光场的压缩参数｜Ｍ｜有关。｜Ｍ｜存在一个阈值Γ４ｇ。阈值之下，原子偶极矩以共振频率振荡；阈值之上，原子偶极矩以三种不同的频率振荡，其中中心频率仍为共振频率，两边频是由中心频率频移而得，这种现象即广义Ｂｌｏｃｈ－Ｓｉｅｇｅｒｔ频移，频移量与压缩真空态场的压缩参数有关。产生广义Ｂｌｏｃｈ－Ｓｉｅｇｅｒｔ频移的原因是双光子过程中压缩真空态光场对原子具有一种“驱动作用”的结果。