A grooved planar ion trap design for scalable quantum information processing

We describe a new electrode design for a grooved surface-electrode ion trap,which is fabricated in printed-circuitboard technology with segmented electrodes.This design allows a laser beam to get through the central groove to avoid optical access blocking and laser scattering from the ion trap surface.The confining potentials are modeled both analytically and numerically.We optimize the radio frequency(rf) electrodes and dc electrodes to achieve the maximum trap depth for a given ion height above the trap electrodes.We also compare our design with the reality ion chip MI I for practical considerations.Comparison results show that our design is superior to MI I.This ion trap design may form the basis for large scale quantum computers or parallel quadrupole mass spectrometers.     

基于二维囚禁离子实现受控非门、交换门和相位门

研究了二维囚禁离子与光场相互作用系统中几种基本量子逻辑门的实现方案.通过适当选取激光场与离子内部跃迁频率的失谐量,简化了系统的哈密顿量,并进一步推导出受控非门(C-NOT门)、交换门与相位门的实现方法.在此过程中,系统需满足Lamb-Dicke极限,并要求光场的Rabi振荡频率远远小于离子的振动频率. 关键词： 囚禁离子 受控非门(C-NOT门) 交换门 相位门     

用于高温射频超导量子干涉器的介质谐振器的性质研究

介质谐振器是目前高温射频超导量子干涉器较常采用的一种高品质因数微波谐振器.它是由10 mm×10 mm×1 mm的SrTiO₃(STO)标准衬底及覆盖在其上的YBa₂Cu₃O_7-δ(YBCO)薄膜磁通聚焦器共同构成的.为探明磁通聚焦器构形对介质谐振器谐振频率的影响,本文采用Ansoft公司出品的HFSS高频结构仿真软件对磁通聚焦器构形不同的若干介质谐振器的谐振特性进行了仿真.结果表明:增大磁通聚焦器开     

A quantum dense coding implementation in an ion trap

This paper reports that a quantum dense coding can be implemented with ions confined in a linear trap and interacting with laser beams. The scheme is insensitive to the interaction between the quantum channel and the environment. The Bell-state measurement is not involved and the probability of success in our scheme is 1.0.     

One scheme for remote quantum logical gates with the assistance of a classical field

A scheme, based on the two two-level atoms resonantly driven by the classical field separately trapped in two cavities coupled by an optical fibre, for the implementation of remote two-qubit gates is investigated. It is found that the quantum controlled-phase and swap gates can be achieved with the assistance of the classical field when there are detunings of the coupling quantum fields. Moreover, the influence of the dissipation of the cavities and the optical fibre is analysed while the spontaneous emission of the atoms can be effectively suppressed by introducing Λ-type atoms.     

A quantum dense coding implementation in an ion trap

This paper reports that a quantum dense coding can be implemented with ions confined in a linear trap and interacting with laser beams. The scheme is insensitive to the interaction between the quantum channel and the environment. The Bell-state measurement is not involved and the probability of success in our scheme is $1.0$.     

Fast generation of cluster states in a linear ion trap

We propose a practical scheme to generate cluster states by simultaneously accomplishing two-qubit conditional gating on an array of equidistant ions by using transverse modes. Our operation is robust to heating and insensitive to Lamb--Dicke parameter. Meanwhile, as it is carried out in a geometric quantum computing fashion, our scheme enables the fast and high-fidelity generation of cluster states. The experimental feasibility is discussed with sophisticated ion trap techniques.     

Grover search algorithm in an ion trap systen

Two schemes for the implementation of the two-qubit Grover search algorithm in the ion trap system are proposed. These schemes might be experimentally realizable with presently available techniques. The experimental implementation of the schemes would be an important step toward more complex quantum computation in the ion trap system.     

Frequency analysis with coupled nonlinear oscillators

We present a method to obtain the frequency spectrum of a signal with a nonlinear dynamical system. The dynamical system is composed of a pool of adaptive frequency oscillators with negative mean-field coupling. For the frequency analysis, the synchronization and adaptation properties of the component oscillators are exploited. The frequency spectrum of the signal is reflected in the statistics of the intrinsic frequencies of the oscillators. The frequency analysis is completely embedded in the dynamics of the system. Thus, no pre-processing or additional parameters, such as time windows, are needed. Representative results of the numerical integration of the system are presented. It is shown, that the oscillators tune to the correct frequencies for both discrete and continuous spectra. Due to its dynamic nature the system is also capable to track non-stationary spectra. Further, we show that the system can be modeled in a probabilistic manner by means of a nonlinear Fokker-Planck equation. The probabilistic treatment is in good agreement with the numerical results, and provides a useful tool to understand the underlying mechanisms leading to convergence.     

Ion energy distribution in a radio frequency sheath of plasma with Kappa electron velocity distribution

A hybrid model consisting of a one-dimensional radio frequency sheath model and an equivalent circuit model is used to investigate the effect of the non-Maxwellian plasma with enhanced electron tails on ion energy distribution (IED) at the plasma–wall interface. With the assumption that electrons obey the Kappa distribution in which the parameter κ characterizes the deviation from Maxwellian distribution, the bimodal shape of the IED can always be found with the decrease of κ under the condition of current experimental advanced superconducting tokamak (EAST) discharges during the ion cyclotron range of frequency wave heating. However, the height of the low-energy peak of the IED decreases, while the high-energy peak does not change significantly. In addition, the IED shifts towards the higher-energy regime, and the width of the IED expands with the decrease of κ . It is also shown that frequency and amplitude of the disturbance current, bulk plasma density, and ion temperature are the crucial parameters for determining the shape of IED even in the presence of super-thermal electrons.     

量子离散Fourier变换在离子阱中的实现方案

在Cirac-Zoller模型的框架下,讨论在离子阱中如何利用幺正操作实施 量子离散Fourier变换的方案。由于量子离散Fourier变换可由两个基本操作组     

Demonstration and operation of quantum harmonic oscillators in an AlGaAs-GaAs heterostructure

Frontiers of Physics - Nonreciprocal microwave devices, in which the transmission of waves is non-symmetric between two ports, are indispensable for the manipulation of information processing and...     

反馈方法在离子阱Doppler冷却中的应用研究

离子阱中离子的快速有效冷却在量子信息处理、光频标等领域都有重要的意义.基于Steixner 等提出的量子反馈模型,将反馈方法应用于离子的Doppler冷却.首先理论分析了该模型下离子运动信息的获取方式以及反馈对离子运动的影响,并推导出了存在反馈时离子运动所满足的方程,然后进行了仿真计算. 计算结果表明,利用量子反馈可以明显的提高离子冷却速率.还分析了反馈参数对离子冷却效率的影响. 关键词： 离子阱 Doppler冷却 量子反馈     

射频电感耦合等离子体在横向磁场中扩散的研究

通过轴向移动朗缪尔探针,考察了外置电磁铁提供的横向磁场对射频感应耦合等离子体(ICP)延轴向扩散过程中的电子温度、离子密度的影响。实验数据表明,与无磁场条件下的结果相比,横向磁场的加入使得扩散区内的电子温度沿轴向迅速下降,研究了横向磁场对电子的过滤作用。     

A scheme of quantum phase gate for trapped ion

We propose a scheme to implement two-qubit controlled quantum phase gate(CQPG) via a single trapped two-level ion located in the standing wave field of a quantum cavity, in which the trap works beyond the Lamb--Dicke limit. When the light field is resonant with the atomic transition $|g\rangle\leftrightarrow|e\rangle$ of the ion located at the antinode of the standing wave, we can perform CQPG between the internal and external states of the trapped ion; while the frequency of the light field is chosen to be resonant with the first red sideband of the collective vibrational mode of the ion located at the node of the standing wave, we can perform CQPG between the cavity mode and the collective vibrational mode of the trapped ion. Neither the Lamb--Dicke approximation nor the assistant classical laser is needed. Also we can generate a GHZ state if assisted with a classical laser.     

离子光频标的研究进展和空间应用展望

现在人们正发展和评估新型的光频标的特点和应用.光频标由于其参考频率在1015的量级,比微波频率高出4—5个数量级,在相同的谱线线宽条件下,光频标的精度与微波频标相比具有很大的优越性,可望成为新的频率基准,有可能在微重力环境中得到应用.     

射频场控制的磁子能级中单色激光吸收抑制

理论上研究了射频场作用下多塞曼能级系统中单色激光的吸收抑制现象.一束单色线偏振或者椭圆偏振的激光作用于铷原子两能级间,线或椭圆偏振矢量方向与磁场方向垂直.在磁场中冷铷原子能级发生分裂,通过一个射频场将这些磁子能级耦合起来.当扫描射频场频率时,计算表明原子对单色光的吸收谱中出现了透射峰,类似于电磁诱导透明现象,光吸收减弱,光场透射增强.对于线性偏振或者椭圆偏振的单色光均能得到透射增强的结果 .这种现象完全不同于通常光泵磁共振实验中射频场与磁子能级谐振时光被吸收最多的现象.这种扫描射频场频率时单色光的透射增强现象来自于磁子能级间的相干效应.计算表明在扫描射频场频率时单色光吸收谱中出现的透射峰与射频场的拉比频率和椭圆偏振光的左旋和右旋圆偏振成分相关.这种射频场控制的单色光透射增强效应在磁场测量,光信息处理等领域有潜在的应用价值.     

射频场控制的磁子能级中单色激光吸收抑制

理论上研究了射频场作用下多塞曼能级系统中单色激光的吸收抑制现象.一束单色线偏振或者椭圆偏振的激光作用于铷原子两能级间,线或椭圆偏振矢量方向与磁场方向垂直.在磁场中冷铷原子能级发生分裂,通过一个射频场将这些磁子能级耦合起来.当扫描射频场频率时,计算表明原子对单色光的吸收谱中出现了透射峰,类似于电磁诱导透明现象,光吸收减弱,光场透射增强.对于线性偏振或者椭圆偏振的单色光均能得到透射增强的结果.这种现象完全不同于通常光泵磁共振实验中射频场与磁子能级谐振时光被吸收最多的现象.这种扫描射频场频率时单色光的透射增强现象来自于磁子能级间的相干效应.计算表明在扫描射频场频率时单色光吸收谱中出现的透射峰与射频场的拉比频率和椭圆偏振光的左旋和右旋圆偏振成分相关.这种射频场控制的单色光透射增强效应在磁场测量,光信息处理等领域有潜在的应用价值.     

Quantum entanglement in a two—dimensional ion trap

In this paper,we investigate the quantum entanglement in a two-dimensional ion trap system.we discuss the quantum entanglement between the ion and phonons by using reduced entropy,and that between two degrees of freedom of the vibrational motion along x and y directions by using quantum relative entropy.We discuss also the influence of initial state of the system on the quantum entanglement and the relation between two entanglements in the trapped ion system.     

二维耦合量子谐振子的本征值和本征函数

运用广义线性量子变换理论,给出一类二维耦合量子谐振子的能量本征值、本征函数、坐标和动量算符在能量表象中的矩阵元及演化算符.