环形碳纳米管-量子点耦合系统的介观输运

应用非平衡格林函数方法研究通过环形碳纳米管-量子点耦合系统的介观输运.相干隧穿与环形碳纳米管和量子点各自的能级结构有强烈的依赖关系,阿哈郎诺夫-玻姆效应使能级周期性变化,隧穿电流则随磁通量作周期性振荡.环形碳纳米管的具体纳米结构显示出金属-半导体相变特性,这种行为也在输出电流中体现出来.子系统量子能级的匹配与失配关系在介观输运过程中起重要作用.     

A Quantum Interpretation of Light Scattering near the Boundary between Transparent Media with Kerr Nonlinearity

The transformation of light by a nonlinear beamsplitter is considered. The beamsplitter is formed by a plane interface between two transparent dielectrics, at least one of which has a Kerr nonlinearity; i.e., its refractive index depends on the intensity of the penetrating radiation. It is shown that the interpretation of the result of calculation of quantum fields at the outputs from such a beamsplitter indicates a violation of the principle of causality in the sense that a subsequent event affects the previous one.     

极化子效应对核壳量子点中光学克尔效应的影响

在有效质量近似下利用量子力学的密度矩阵理论,采用无限深势阱模型解三维薛定谔方程得到电子的本征能量和波函数.从理论上计算了考虑极化子效应后,在导带子带间跃迁时ZnS/CdSe柱型核壳结构量子点光学克尔效应的三阶极化率.通过数值计算,分析了电子-LO声子和电子-IO声子相互作用对ZnS/CdSe柱型核壳结构量子点光学克尔效应的三阶极化率的影响.结果表明:极化子效应对光学克尔效应的三阶极化率有很大影响,并且影响的大小与量子点的尺寸大小有关.     

极化子效应对核壳量子点中光学克尔效应的影响

在有效质量近似下利用量子力学的密度矩阵理论,采用无限深势阱模型解三维薛定谔方程得到电子的本征能量和波函数.从理论上计算了考虑极化子效应后,在导带子带间跃迁时ZnS/CdSe柱型核壳结构量子点光学克尔效应的三阶极化率.通过数值计算,分析了电子-LO声子和电子-IO声子相互作用对ZnS/CdSe柱型核壳结构量子点光学克尔效应的三阶极化率的影响.结果表明：极化子效应对光学克尔效应的三阶极化率 有很大影响,并且影响的大小与量子点的尺寸大小有关.       

Self-Localization of Light Beams in a Medium with Instantaneous Kerr Nonlinearity Switching

Journal of Experimental and Theoretical Physics - A model is proposed for the nonlinear response of a medium in which the permittivity depending on the field intensity is instantaneously switched...     

Quantum Entanglement in Two-Photon Tavis–Cummings Model with a Kerr Nonlinearity

The properties of quantum entanglement in the two-photon Tavis–Cummings model with a Kerr nonlinearity are studied in terms of quantum information entropy theory. The reduced quantum entropy is employed to investigate the quantum entanglement between two two-level atoms and a single-mode coherent field. The relative quantum entropy is employed to investigate the quantum entanglement between the two two-level atoms. The influences of the nonlinear interaction of the Kerr medium with the field and the atomic dipole-dipole interaction on the properties of quantum entanglement of the system are also examined. Some important results are obtained.     

Nonlocal Gate of a Quantum Network via Cavity Quantum Electrodynamics

We propose an experimentally feasible scheme to realize the nonlocal gate between two different nodes of a quantum network. With an entanglement-qubit acts as a quantum channel, our scheme is resist to actual environment noise and can get a high fidelity in current cavity quantum electrodynamics （C-QED） system.     

Entanglement Transfer Between Cavity Fields and Excitons in a Driven Quantum Dot System

We investigate entanglement transfer from two separate cavities to the excitons in two quantum dots separately placed in the two cavities. The cavity fields and the excitons are treated as two continuous-variable （CV） subsystems. The time-dependent characteristic functions in the Wigner representation for the two subsystems are analytically obtained. Under the conditions that one of the two CV subsystems is initially prepared in a two-mode squeezed vacuum state and the other in its lowest energy state, we show that the entanglement reciprocation between the cavity fields and the excitons is realizable.     

Enhanced Cross-Phase Modulation via Phase Control in a Quantum dot Nanostructure

A four-level quantum dot (QD) nanostructure interacting with four fields (two weak near-infrared (NIR) pulses and two control fields) forms the well-known double-cascade configuration. We investigate the cross-phase modulation (XPM) between the two NIR pulses. The results show, in such a closed-loop scheme, that the XPM can be greatly enhanced, while the linear absorption and two-photon absorption (gain) can be efficiently depressed by tuning the relative phase among the applied fields. This protocol may have potential applications in NIR all-optical switch design and quantum information processing with the solid-state materials.     

A New Theoretical Model of a Carbon Nanotube Strain Sensor

Carbon nanotubes （CNTs） are potential strain sensors due to their excellent mechanical and spectral properties. A new theoretical model of a CNT strain sensor is obtained by applying the polarized Raman properties of CNTs, which calculates the synthetic contributions of Raman spectra from the CNTs in random directions. By using this theoretical model, the analytic relationship between planar strain components and the Raman shift increment of uniformly dispersed CNTs is obtained, which is applicable for accurately characterizing the strain in random directions on the surface of a measured microsystem.     

Reinforcing of a Mirror Surface via the Deposition of a Carbon Nanostructure

Optics and Spectroscopy - The problem of reinforcing the mirror surfaces of space-based astronomical optics and their protection against external factors is discussed. To solve this problem, the...     

玻璃掺杂量子点的倍频效应产生的理论研究

应用统计理论和量子力学理论对量子点掺杂的倍频效应产生的机制与量子点倍频光的电极化率与量子点的尺寸大小的关系进行了理论研究，结果较好地解释了实验所观察到的规律。     

非阿贝尔腔量子电动力学模型下偏振光场的影响

通过使用场正交算符,而不是传统的玻色算符,研究了非阿贝尔腔量子电动力学(QED)模型中原子和偏振光场的相互作用。讨论了初始双模偏振光场对于原子布居数反转以及偏振光场的压缩特性的影响。结果表明,原子布居数反转的演化不仅与偏振椭圆的相位角有关,也与偏振椭圆的椭率角有关;只有当偏振椭圆是右旋圆偏振光时,原子布居数反转随时间的演化基本不变,趋近于初始值0,而当偏振椭圆是左旋圆偏振光时,原子布居数反转随时间的演化呈现周期性的崩塌复苏变化。另外,当初始光场是左旋圆偏振光时,光场可以出现周期性的压缩;而当初始光场是右旋圆偏振光时,光场的压缩不会持续出现。     

Recent Advances of Light Propagation in Surface Plasmon Enhanced Quantum Dot Devices

Surface plasmons are of particular interest recently as their performance is approaching the enhancement of light emission efficiencies, after synthesized close to the vicinity of solid state materials, i.e., semiconductor structure. As other scientific works have been proposed to improve the light-emitting efficiency, such as the use of resonant cavities, photon recycling, and thin-light emitting layers with periodic surface texturing, surface plasmon possesses a promising way to the light enhancement, due to the energy coupling effect between the emitted photons from the semiconductor and the metallic nanoparticles fabricated by nanotechnology. The usual pathway of plasmon enhanced light emitting devices is the use of Ag/Au nanoparticles coating the surface of semiconductor quantum dot (QD) or quantum well (QW) structures. However, apart from efforts to extract as much light as possible from single-driven surface plasmon-QD/QW, it is possible to enhance the light emission rate with double optical-excitations. This approach is based on the quantum interference between the external lasers and the localized quantum light, and promised to stimulate the development of plasmon-enhanced optical sensors. In this review, we describe the quantum properties of light propagation in hybrid nanoparticle and semiconductor materials, i.e., quantum dot or nanomechanical resonator coupled to Ag/Au nanoparticles, driven by two optical fields. Distinct with single excitation, plasmon-assisted complex driven by two optical fields, exhibit specific quantum interference characteristics that can be used as sensitive all-optical devices, such as the slow light switch, nonlinear optical Kerr modulator, and ultra-sensitive mass sensing. We summarize the recent advances of light propagation in surface plasmon-enhanced quantum dot devices, driven by two optical fields, which would stimulate the development of novel optical materials, deeper theoretical insights, innovative new devices, and plasmonic applications with potential for significant technological and societal impact.     

Quantum Transition of Two-Level System in a Parabolic Quantum Dot

The time evolution of the quantum mechanical state of an electron is calculated by using variational method of Pekar type on the condition of electric-LO phonon strong coupling in a parabolic quantum dot. We obtained the eigen energies of the ground state and the first-excited state, the eigen functions of the ground state and the first-excited state this system in a quantum dot may be employed as a two-level quantum system-qubit. The supposition electron is in system’s ground state in the initial time, the electron transit from the ground state to the excited state in presence of an electric field F along the x axis. The results indicate that the electron transition probability and the oscillation period increase with decreasing the electron-LO-phonon coupling constant, increasing the electric field and the confinement length.     

量子点中Stark效应及微观电极化率的理论研究

以半导体材料InSb为研究对象,利用有效质量近似方法,分别研究了在强弱电场下含有两个电子的量子点中的能级移动.首先,利用微扰法计算了库仑相互作用所引起的能量变化ΔE,计算由于弱电场而引起的Stark能级移动ΔE1,并研究了ΔE1与特征长度L的关系;其次,在强电场作用下,用解薛定谔方程的方法求出了能量变化ΔE2并将其与弱电场下的情况进行对比;最后,在此基础上利用非线性光学知识研究了强电场作用下微观电极化率χ是随着L的增加而增大的.     

介质中双缺陷电荷对碳纳米管场效应晶体管量子输运特性的影响

用非平衡格林函数理论和紧束缚模型近似计算长沟道弹道输运p型碳纳米管场效应管中电流强度.研究当场效应管介质（SiO₂）中存在两个带电缺陷时，载流子散射所引起的电流强度减小和栅极阈值电压偏移量与缺陷位置的关系.介质中两个缺陷所带电荷Q₁=Q₂=+e（-e为电子电荷），都靠近源极或者都靠近漏极，或者一个电荷靠近源极另一个电荷靠近漏极.在工作状态下，所引起的电流强度相对减小比介质中只存在单个正电荷Q=+e且靠近源极（或漏极）时所引起的电流强度相对减小大得多.如果两个正电荷都在沟道中央附近，随着两个电荷的轴向距离减小，栅极阈值电压偏移的绝对值明显增加.栅极阈值电压偏移可达到-0.35 V.     

Implementation of Quantum Controlled-Not Gates via Singly Charged Quantum Dots in Cavity QED

The CNOT gates for photon-photon and photon-electron are constructed in quantum dot-cavity system based on the properties of singly charged dots in strong and weak-coupling cavities. The fidelities of these gates can reach relatively high values even if the cavity decay and leakage are considered. These types of gate plays an important role in hybrid quantum information systems. By using the wavelength division multiplexer (WDM) and polarization maintaining fiber circulator (PMFC) in the setup the success probabilities of the schemes are improved.     

Theoretical Study of Millimeter Wave Harmonic Oscillator Stabilized with a Transmission Cavity

An equivalent circuit model of millimeter wave second harmonic oscillator stabilized with a transmission cavity has been proposed for constructing analytical formulations between performance parameters of the oscillator and parameters of the circuit. The model consists of an equivalent circuit of fundamental wave and that of second harmonic wave. Each of the circuits comprises circuit models of main cavity, transmission waveguide, and transmission cavity. Absorbing material placed between the transmission waveguide and the transmission cavity can suppress additional resonances originated from transmission cavity. The behavior of the second harmonic oscillator can be effectively described by the circuit model. Furthermore, based on this model, mechanical tuning characteristics have been studied at first, and then analytical formulas for quality factor and efficiency depending on circuit parameters have been derived. The circuit parameters can be conveniently extracted by electromagnetic field simulation. Hence the formulas exhibit both compact form and enough accuracy. Thereafter, general rules of performance parameters varying with circuit parameters have been deduced for the harmonic oscillators. Then some design considerations have been derived according to the corresponding analysis. The equivalent circuit model is useful for designing and adjusting millimeter wave second harmonic stabilizing oscillator with a transmission cavity.