Quantum interference rectifier

Electron transport in bent quantum wire in the presence of a magnetic field which is orthogonal to the system plane is considered. Possible constructions of “quantum interference switch” and “quantum interference rectifier” are suggested.     

Quantum interference at corners

We show that a radiating atom, or molecule, localised at sub-wavelength distances from a corner arising from the intersection of three planar material surfaces, exhibits novel quantum interference effects. The simplest case arises for a corner formed by the intersection of three perfect conductors, all at right angles. This situation is shown here to give rise to super-radiance and sub-radiance effects that are highly sensitive to the dipole moment orientation and position of the radiating atom or molecule in the vicinity of the corner.     

双色场中钾原子的量子干涉现象

采用多态展开方法,对里德堡钾原子与双色场相互作用时诱发的量子干涉效应进行了研究计算,讨论和分析了布居数跃迁过程中的干涉相长及相消的原因.     

Quantum interference and diffraction of parametric down-converted biphotons

We present two-photon diffraction and interference experiments utilizing parametric down-converted photon pairs (biphotons) and a transmission grating. The biphoton exhibits a diffraction-interference pattern equivalent to an effective single particle with half wavelength of the constituent photons.     

基于旋滤波的散斑干涉图预处理方法

介绍了旋滤波算法中窗口大小变化对滤波效果的影响,得出旋滤波的窗口应该取在约1/4条纹宽度的结论。处理了大散斑噪声的干涉图,发现窗口尺寸必须超过散斑尺寸才能得到比较好的滤波效果。确定了旋滤波算法应用的范围是大于散斑尺寸,且在1/4条纹宽度处比较合适。针对滤波后条纹对比度降低的问题,使用灰度拉伸的方法进行对比度增强。     

不同后处理方法对溶胶-凝胶SiO2膜层抗污染能力的影响

以正硅酸乙酯作为前驱体,利用碱催化方式制备了SiO2溶胶,采用提拉法在K9基片上镀制SiO2单层薄膜,分别用热处理、紫外辐射处理、氨水加六甲基二硅胺烷气氛处理和酸碱复合膜4种后处理法对膜层进行处理,采用分光光度计、红外光谱、扫描探针显微镜、静滴接触角测量仪、椭偏仪等分析了薄膜的特性,通过真空环境加速污染实验对处理前后的膜层进行抗污染能力对比,结果表明:在碱性SiO2膜层上加镀一层酸性SiO2膜的复合膜层整体透过率仍保持在99%以上,疏水角达到128°,膜层真空抗污染能力大大加强。     

基于Rb原子电磁诱导透明的量子干涉实验研究

报道了基于85RbD2线电磁诱导透明(EIT)的量子干涉现象,发现当一耦合光和探测光之间满足拉曼共振条件时出现电磁诱导透明现象,在某些条件下也观察到电磁诱导吸收(EIA).而当用一束耦合光和一束泵浦光共同作用于5S1/2,F=3→5P3/2,F′=3和5S1/2,F=3→5P3/2,F′=4能级上时,探测光的吸收谱表现出三峰结构,并且峰强弱与两耦合光之间的相对强度有关.     

Quantum interference effect in few-layered transition metal dichalcogenide

Van der Waals layered transition metal dichalcogenides (TMDCs), as atomically flat two-dimensional materials, have been studied extensively in both fundamental science and application fields in recent years. The reduced-dimensional properties of TMDCs not only provide a route for the fabricating of efficient field effect transistors and optoelectronic devices but also suggest the possibility of the devices that utilize quantum coherency. In this work, we characterize the electron transport properties of ReS₂, one of the TMDCs, at both room temperature and low temperature. Of particular note, we measured strong quantum conductance oscillations as a function of the gate voltages and source-drain voltages at reduced temperature, which is evidence of quantum coherent transport. This work unambiguously establishes ReS₂ as a promising candidate for future quantum materials.     

Quantum interference between a single-photon Fock state and a coherent state

We derive analytical expressions for the single mode quantum field state at the individual output ports of a beam splitter when a single-photon Fock state and a coherent state are incident on the input ports. The output states turn out to be a statistical mixture between a displaced Fock state and a coherent state. Consequently we are able to find an analytical expression for the corresponding Wigner function. Because of the generality of our calculations the obtained results are valid for all passive and lossless optical four port devices. We show further how the results can be adapted to the case of the Mach-Zehnder interferometer. In addition we consider the case for which the single-photon Fock state is replaced with a general input state: a coherent input state displaces each general quantum state at the output port of a beam splitter with the displacement parameter being the amplitude of the coherent state.     

Asymmetric multimode interference isolator based on nonreciprocal phase shift

This paper presents an asymmetric multimode interference-based (MMI) optical isolator, by utilizing the magneto-optical nonreciprocal phase shift (NPS). Equivalent beam propagation method (BPM) simulation of symmetric and asymmetric isolators are performed using configuration of Air/Ce:YIG/SiO₂ on silicon substrate for integration. The asymmetric isolator is found to be much more compact in size and efficient in isolation compared with symmetric isolator. Simulation results show that the isolation of asymmetric structure is 23.8 dB higher than that of symmetric one. It is mainly because both symmetric mode and anti-symmetric mode are excited in asymmetric structure and hence can interfere destructively. The proposed device may play an important role in the optical communication systems and photonic integrated devices.     

Quantum noise limits to terabaud communications

From a general model of fiber optics, we investigate the physical limits of soliton-based terabaud communication systems. In particular we consider Raman and initial quantum noise effects which are often neglected in fiber communications. Simulations of the position diffusion in dark and bright solitons show that these effects become increasingly important at short pulse durations, even over kilometer-scale distances. We also obtain an approximate analytic theory in agreement with numerical simulations, which shows that the Raman effects exceed the Gordon-Haus jitter for sub-picosecond pulses.     

相干瞬态的量子干涉效应和Berry相位

利用解析方法描述了相干瞬态量子体系中不同类型的量子干涉效应,分别讨论了光学干涉与量子干涉所起的作用,分析了在时域对称光场作用下,几何相位在量子干涉效应中所扮演的角色,从理论上证明了通过适当改变抽运场脉冲面积,可实现对几何相位的测量. 同时研究也发现利用啁啾抽运场可以实现对量子干涉效应的有效控制. 关键词： 相干瞬态 量子干涉 几何相位 啁啾脉冲     

量子相变

量子相变是一种发生在绝对零度,由量子涨落而非热涨落导致的相变现象,满足著名的海森堡不确定关系。通过零温量子临界点的研究,可获知物质系统更广泛范围的行为,包括稀土磁性绝缘体,高温超导体和二维电子气体等。     

Quantifying interference in multipartite quantum systems

The characterization of quantum correlations is crucial to the development of new quantum technologies and to understand how dramatically quantum theory departs from classical physics. Here we systematically study single- and multiparticle interference patterns produced by general two- and three-qubit systems. From this we establish on phenomenological grounds a new type of quantum correlation for these systems, which we name quantum interference, deriving some quantifiers that are given explicitly in terms of the density matrix elements of the complete system. By using these quantifiers, we show that, contrary to our expectations, entanglement is not a required property for a composite quantum system to manifest multiparticle interference.     

An analytical study on absorptive lineshape of a driven N-type open four-level system: Quantum interference effects

An open four-level system of having two pairs of closely spaced levels (N-type configuration) is driven by a single electromagnetic field and tuned resonant with the average frequency of four dipole allowed transitions. Under the Doppler free condition and by using a semiclassical formulation of atom-field interaction for four dipole allowed transitions, we derive the optical Bloch equations for the said four-level system coupled to the driving field. In order to obtain the field induced polarization and hence the absorptive lineshapes, we use the usual perturbation method for getting the approximate analytical solution to the coupled optical Bloch equations for the density matrix elements. Through the off-diagonal complex density matrix elements, we introduce the field dependent phase angles arising out of the quantum interference between the levels participating in dipole allowed transitions. The difference between the field dependent and field independent phases are pointed out. In particular, we investigate the effects of Rabi frequencies and the field dependent phases on the absorptive lineshape. The analytical expressions for the effective linewidths, effective detunings and the induced polarization clearly indicate the role of quantum interference.     

Quantum interference of charged identical particles

We present the results of a computer simulation study of charged-particle interferometry, combining features of both the Aharonov-Bohm and Hanbury Brown-Twiss experiment. In contrast to a previous theoretical analysis of this experiment, we find that the Aharonov-Bohm effect is also present in the cross-correlated two-particle intensity. A simple, time-independent scattering theory that leads to conclusions that are in concert with the simulation data is given.     

非高斯冲激干扰下基于Softplus函数的核自适应滤波算法

针对非高斯环境下一般自适应滤波算法性能严重下降问题,本文提出了一种基于Softplus函数的核分式低次幂自适应滤波算法(kernel fractional lower algorithm based on Softplus function,SP-KFLP),该算法将Softplus函数与核分式低次幂准则相结合,利用输...