Cavity Field Spectra of a Cascade Three-Level Atom Interacting with a Single-Mode Field with Kerr-Like Medium

串联的洞地光谱有在洞中等的象 Kerr 一样的三水平的原子交往 withsingle 模式地被调查。处于纯数字状态，协调状态和挤压的真空状态的起始的地的数字结果分别地是计算的。象 Kerr 一样媒介影响，这被发现光谱尽管当原子在上面的水平时，起始的地在真空，组织。在强壮的输入地的情况中，然后，棕土状态光谱与不同高度显示出二座山峰；并且重叠状态系列 hows 有二座附近的山峰的相等的距离的多山峰结构。光谱“中央频率”与增加平均光子数字变离开反响的频率。

Realization of Toffoli gate operation using four-level atoms in cavity QED system

This paper proposes a scheme for realization of a three-qubit Toffoli gate operation using three four-level atoms by a selective atom-field interaction in a cavity quantum electrodynamics system. In the proposed protocol, the quantum information is encoded on the stable ground states of atoms, and atomic spontaneous emission is negligible as the large atom-avity detuning effectively suppresses the spontaneous decay of the atoms. The influence of the dissipation on fidelity and success probability of the three-qubit Toffoli gate is also discussed. The scheme can also be applied to realize an N-qubit Toffoli gate and the interaction time required does not rise with increasing the number of qubits.

Population Dynamics and Emission Spectrum of a Cascade Three-Level Jaynes-Cummings Model with Intensity-Dependent Coupling in a Kerr-like Medium

<正> By using the method of eigenvectors,the atomic populations and emission spectrum are investigated in asystem that consists of a cascade three-level atom resonantly interacting with a single-mode field in a Kerr-like medium.The atom and the field are assumed to be initially in the upper atomic state and the Fock state,respectively.Resultsfor models with intensity-dependent coupling and with intensity-independent coupling are compared.It is found thatboth population dynamics and emission spectrum show no indications of atom-field decoupling in the strong field limitif the intensity-dependent coupling is taken into account.

Dynamic Equations and Nonlinear Dynamics of Cascade Two-Photon Laser

我们导出方程并且学习二光子的激光，在洞的电磁的地被协调地准备的三水平的原子和古典地在驾驶注入了洞的串联的非线性的动力学。如此的一个系统的动态方程被使用量 Langevin 操作员的技术导出，然后在不同开车条件下面数字地被学习。结果在某些条件下面显示出那二光子的激光能产生的串联混乱，加倍的时期，周期、稳定、双稳态的状态。混乱能被原子人口，原子连贯，和注射的古典地禁止。另外，没有混乱发生在光双性人稳定性。

Molecular dynamics simulations of displacement cascades in Fe-10%Cr systems

Molecular dynamics simulations of the displacement cascades in Fe 10%Cr systems are used to sinmlate the primary knocked-on atom events of the irradiation damage at temperatures 300, 600, and 750 K with primary knockedon atom energies between 1 and 15 keV. The results indicate that the vacancies produced by the cascade are all in the central region of the displacement cascade. During the cascade, all recoil Fe and Cr atoms combine with each other to form Fe Cr or Fe Fe interstitial dumbbells as well as interstitial clusters. The number and the size of interstitial clusters increase with the energy of the primary knocked-on atom and the temperature. A few large clusters consist of a large number of lee interstitials with a few Cr atoms, the rest are lee Cr clusters with small and medium sizes. The interstitial dumbbells of Fe lee and Fe-Cr are in the （111）and （110） series directions, respectively.

Fluorescence properties in a single driven four-level atomic system

The spontaneous emission decay dynamics of a tripod configuration four-level atom driven by a single laser field is studied. Under different initial conditions, we discuss the effects of quantum interference and detuning of external driving field on atomic spontaneous emission properties. For the larger detuning, the interesting phenomena of the spectral line narrowing are found which stem from the contribution of external driving field.

Two-dimensional atom localization via probe absorption in a four-level atomic system

We have investigated the two-dimensional （2D） atom localization via probe absorption in a coherently driven four-level atomic system by means of a radio-frequency field driving a hyperfine transition. It is found that the detecting probability and precision of 2D atom localization can be significantly improved via adjusting the system parameters. As a result, our scheme may be helpful in laser cooling or the atom nano-lithography via atom localization.

Channel Estimation for Reconfigurable Intelligent Surface Aided Multiuser Millimeter-Wave/THz Systems

It is assumed that reconfigurable intelligent surface(RIS)is a key technology to enable the potential of mmWave communications.The passivity of the RIS makes channel estimation difficult because the channel can only be measured at the transceiver and not at the RIS.In this paper,we propose a novel separate channel estimator via exploiting the cascaded sparsity in the continuously valued angular domain of the cascaded channel for the RIS-enabled millimeter-wave/Tera-Hz systems,i.e.,the two-stage estimation method where the cascaded channel is separated into the base station(BS)-RIS and the RIS-user(UE)ones.Specifically,we first reveal the cascaded sparsity,i.e.,the sparsity exists in the hybrid angular domains of BS-RIS and the RIS-UEs separated channels,to construct the specific sparsity structure for RIS enabled multi-user systems.Then,we formulate the channel estimation problem using atomic norm minimization(ANM)to enhance the proposed sparsity structure in the continuous angular domains,where a low-complexity channel estimator via Alternating Direction Method of Multipliers(ADMM)is proposed.Simulation findings demonstrate that the proposed channel estimator outperforms the current state-of-the-arts in terms of performance.

High-dimensional atomic microscopy in surface plasmon polaritons

We develop a new scheme of two-dimensional(2D)and three-dimensional(3D)atom localization via absorption and gain spectra of surface plasmon polaritons(SPPs)in a closed loop four-level atomic system.For the atom–field interaction,we construct a spatially dependent field by superimposing two(three)standing-wave fields(SWFs)in 2D(3D)atom localization,respectively.We achieve high-precision and high spatial resolution of an atom localization by appropriately adjusting the system parameters such as probe field detuning and phase shifts of the SWFs.The absorption and gain spectra are used to attain information about the position of an atom in SPPs.Our proposed scheme opens up a fascinating way to improve the atom localization that supplies some practical applications in a high-dimensional SPPs.

Low-energy atomic displacement model of SRIM simulations

Radiation-induced atomic displacement damage is a pressing issue for materials.The present work investigates the number of atomic displacements using the Primary Knock-on Atom (PKA) energy E_(PKA)and threshold displacement energy E_(d)as two major parameters via lowenergy SRIM Binary Collision Approximation (BCA) full cascade simulations.It is found that the number of atomic displacements cannot be uniquely determined by E_(PKA)/E_(d )or E_(D) /E_(d)(E_(D) refers to the damage energy) when the energy is comparable with E_(d).The effective energy E_(D,eff)proposed in the present work allows to describing the number of atomic displacements for most presently studied monatomic materials by the unique variable E_(D,eff)/E_(d).Nevertheless,it is noteworthy that the BCA simulation damage energy depends on E_(d),whereas the currently used analytical method is independent of E_(d).A more accurate analytical damage energy function should be determined by including the dependence on E_(d).

Defect production and atomic mixing by displacement cascades in Ni_3Al

Molecular dynamics simulations have been employed to investigate displacement cascades in Ni3Al, with energy Ep in the range from 0.15 to 10 keV. The efficiency of production of Frenkel pairs declines with the increasing cascade energy in a fashion similar to that found recently for pure metals. The antisite defects are much more numerous than the Frenkel pairs, and their production efficiency increases with the increasing cascade energy. A new empirical relationship between the defect number and damage energy is proposed, namely Ndefect = AEpm. A high proportion of the atomic mixing occurs in the ballistic phase and is larger for the Ni atoms, implying that the phenomenon is not purely a liquid-like process.

Determination of hyperfine structure constants of 5D_(5/2) and 7S_(1/2) states of rubidium in cascade atomic system

We present a method to precisely determine the hyperfine structure constants of the rubidium 5D（5/2） and 7S（1/2） states in a cascade atomic system. The probe laser is coupled to the 5S（1/2）→ 5P（3/2） hyperfine transition, while the coupling laser is scanned over the 5P（3/2）→ 5D（5/2）（7S（1/2）） transition. The high-resolution double-resonance optical pumping spectra are obtained with two counter-propagating laser beams acting on rubidium vapor. The hyperfine splitting structures are accurately measured by an optical frequency ruler based on the acousto-optic modulator, thus, the magnetic dipole hyperfine coupling constant A and quadrupole coupling constant B are determined. It is of great significance for the atomic hyperfine structure and fundamental physics research.

低能重离子及其碰撞产生的级联原子在生物材料中的直接作用范围

用ＭｏｎｔｅＣａｒｌｏ法模拟计算了３０ｋｅＶ和２００ｋｅＶ的矿与１１０ｋｅＶ的Ｆｅ＋在模拟细胞中的射程分布和径迹结构，并将１１０ｋｅＶＦｅ＋模拟计算的结果与ＲＳＢ测量的结果相比较，发现计算与测量的结果吻合较好，离子的作用范围小于１μｍ．计算和实验的结果都说明能量相当低的重离子不大可能直接作用引起麦胚深层生物效应．在不考虑热扩散效应的情况下，还用ＭｏｎｔｅＣａｒｌｏ方法模拟计算了２００ｋｅ的Ｎ＋产生的级联原子在模拟的细胞中的作用范围，得出其虽有前冲但作用范围仍然小于１．５μｍ的结论．最后讨论了低能重离子注入出现生物效应的可能原因．

强场与级联型三能级原子相互作用中原子的偶极压缩效应

采用数值计算方法研究了强相干初态光场与级联型三能级原子相互作用中原子的偶极压缩效应 结果表明 :级联型三能级原子偶极算符的两个正交分量均呈现出周期性的压缩现象 ,原子存在偶极压缩 ,且压缩的最大深度比弱场作用情况下要深得多 ;随着 n值的不断增大 ,偶极算符两个正交分量的振荡频率随之增大 ,场与原子的非线性耦合越来越强 。

级联三能级运动原子与单模场相互作用系统中光子的反聚束效应

研究了一个Ξ型三能级运动原子与单模场相互作用系统中光子的反聚束效应,着重讨论了不同初始态下,原子运动速度和模场结构与强度对光子反聚束效应的影响。

驱动场相位扩散对三能级梯型系统无反转激光的影响(英文)

在旋波、慢变振幅近似下,求解考虑了驱动场相位扩散后的系统密度矩阵运动方程,并给出了这个三能级梯型系统稳态线性解析解。利用得到的稳态线性解析解分析驱动场相位扩散是如何影响该系统输出无反转激光的。对稳态线性解析解数值计算的结果显示:由于驱动场相位扩散会导致无反转激光增益减小;即使由于驱动场相位扩散引起的线宽足够大,在该系统中仍能够获得无反转激光;线宽往往是破坏无反转激光产生和折射率的提高;因驱动场相位扩散导致无反转激光增益的减小,并不是总能够通过增大驱动场的Rabi频率得到补偿。

级联三能级原子的偶极振幅平方压缩

本文在文献［４］的基础上，定义了三能级原子的偶极振幅平方算符，进而由海森伯测不准关系，提出了三能级原子的偶极振幅平方压缩．研究了与关联双模压缩真空场作用的级联三能级原子的偶极振幅平方压缩效应．通过数值计算，讨论了初始压缩光场的压缩参数、单光子失谐量以及原子—光场耦合强度对原子偶极振幅平方压缩的影响．

与关联双模辐射场作用的级联三能级原子的偶极压缩效应

研究了与关联双模压缩真空场作用的级联三能级原子的偶极压缩效应。通过数值计算 ,讨论了初始压缩光场的压缩参数、单光子失谐量以及原子—光场耦合强度对原子偶极压缩的影响。

基于腔量子电动力学的制备四光子GHZ态简单方法(英文)

提出一种利用阶梯型三能级原子与两个双模腔谐振相互作用制备四光子GHZ态的方案。在该方案中,量子信息编码在腔场的Fock态中。通过求解薛定谔方程,得到相互作用系统的量子态。原子通过两个腔后被测量时,场能崩塌到所需要的GHZ态。结果表明该方案简单且实验上可行。