Schrdinger Cat States in a Mesoscopic Josephson Junction

To study the nonclassical effects of the mesoscopic Josephson junction in the presence of a nonclassical microwave, the mesoscopic Josephson junction and the field were both treated quantum mechanically, and the external field approximation was used. It is shown that if the external field is in the coherent state and the state of the junction is initially prepared in the vacuum state, the state of the junction can evolve into a quantum superposition of two coherent states. The Schrdinger cat states can be produced in a mesoscopic Josephson junction.

Entropy evolvement properties in a system of Schrodinger cat state light field interacting with two entangled atoms

The field entropy can be regarded as a measurement of the degree of entanglement between the light field and the atoms of a system which is composed of two-level atoms initially in an entangled state interacting with the Schroedinger cat state. The influences of the strength of light field and the phase angle between the two coherent states on the field entropy are discussed by using numerical calculations. The result shows that when the strength of light field is large enough the field entropy is not zero and the degrees of entanglement between the atoms and the three different states of the light fields are equal. When the strength of the light field is small, the degree of entanglement is maximum in a system of the two entangled atoms interacting with an odd coherent state; it is intermediate for a system of the two entangled atoms interacting with the Yurke-Stoler coherent state, and it is minimum in a system of the two entangled atoms interacting with an even coherent state.

Implementing the Deutsch-Jozsa algorithm by using Schrodinger cat states in cavity QED

We propose a scheme to implement the Deutsch-Jozsa algorithm by using Schroedinger cat states in cavity quantum electron-dynamics （QED）. The scheme is based on the Raman interaction of a degenerate three-level A-type atom with a coherent state in a cavity. By using Schroedinger cat states, the atomic spontaneous emission can be minimized and the Hadamard transformation in our scheme is not needed.

Alternative Scheme for Generation of Atomic Schrdinger Cat States and Entangled Coherent States in an Optical Cavity

We propose an alternative scheme for generation of atomic Schrodinger cat states in an optical cavity. In the scheme the atoms are always populated in the two ground states and the cavity remains in the vacuum state. Therefore, the scheme is insensitive to the atomic spontaneous emission and cavity decay. The scheme may be generalized to the deterministic generation of entangled coherent states for two atomic samples. In contrast with the previously proposed schemes of [Commun. Theor. Phys. 40 （2003） 103 and Chin. our scheme is greatly shortened and thus the deeoherence can Phys. B 18 （2009） 1045], the required interaction time in be effectively suppressed.

Generation of Schrdinger cat state of a single trapped cold ion

The fidelity of the generated Schrodinger Cat state （SCS） of a single trapped ion in the Lamb-Dicke approximation is discussed. The results show that the fidelity significantly decreases with the values of Lamb-Dicke parameter η and coherent state amplitude α increasing. For η= 0.20 and α = 3, the typical values of experimental parameters, the fidelity is rather low （3070）. A scheme for generating the SCS is proposed without making the Lamb-Dike approximation in laser-ion interaction, and the fidelity of the generated SCS is about 99% for the typical values of experimental Lamb- Dicke parameters.

Entanglement between two atoms in the system of SchrSdinger cat state interacting with two entangled atoms

By the negative eigenvalues of partial transposition of density matrix, this paper investigates the time evolution of entanglement of the two entangled atoms in the system of two atoms interacting with SchrSdinger cat state. The result shows that the two atoms are always in the entanglement state, and the degree of entanglement between the two atoms exhibits ordinary collapses and revivals at 0.2 degree of entanglement, when the light field is large enough. On the other hand, the reinforcement of three different light fields on the degree of entanglement between two atoms is not evident.

Preparing quantum vortex states with odd Schrdinger cat states through a coupled waveguide system

A scheme is proposed for preparing a quantum vortex state with a coupled waveguide, in which a single-mode odd cat state with weak intensity and a single-mode coherent state are inserted in the input ports, respectively. The analytical wavefunction of the resulting state in the quadrature space is derived, and the vortex structure of the output state is analyzed. It is found that the obtained states, which may carry a vortex with topological charge index one, are entangled and nonclassical, depending only on the scaled propagation time and the weak intensity of the input odd cat state instead of the displacement parameter of the input coherent state. The phase distribution, however, in the quadrature space, depends on the displacement parameter of the input coherent state

Entanglement and Teleportation of Pair Cat States in Amplitude Decoherence Channel

The dynamic behavior of the entanglement for the pair cat states in the amplitude decoherence channel isstudied by adopting the entanglement of formation determined by the concurrence.Then,we consider the teleportationby using joint measurements of the photon-number sum and phase difference with the pair cat states as an entangleresource and discuss the influence of amplitude decoherence on the mean fidelity of the teleportation.

Preparation of multicomponent Schrodinger cat states through resonant atom-field interaction

A simple method is presented for generating multicomponent Schrodinger cat states through resonant atom-field interactions. In the scheme n two-level atoms, initially in ground states, are sent through a resonant cavity filled with a strong coherent field sequentially. Then state-selective measurements are performed on the atoms. The detections of the atoms in ground states collapse the cavity field onto a superposition of 2(n) coherent states. This is the first way for producing superpositions of many coherent states through resonant atom-field interaction.

A scheme for teleporting Schridinger-cat states via the dispersive atom-cavity-field interaction

A proposal is presented for teleporting Schr*iding-cat states. The process of the teleportation is achieved through the dispersive atom-cavity-field interaction. In this proposal, only measurement on the cavity field and on the singlet atomic states are used.

Nonreciprocal generation of Schrodinger cat state induced by topology

The Schrodinger cat state produced differently in two directions is anticipated to be a critical quantum resource in quantum information technologies.By exploring the interplay between quantum nonreciprocity and topology in a one-dimensional microcavity array,we obtain the Schrodinger cat state(a pure quantum state)in a chosen direction at the edge cavity,whereas a classical state in the other direction.This nonreciprocal generation of the cat state originates from the topologically protected chiralitymode excitation in the nontrivial phase,but in the trivial phase,the nonreciprocal generation of cat state vanishes.Thus,our proposal is switchable by tuning the parameters so that a topological phase transition occurs.Moreover,the obtained cat state has nonreciprocal high fidelity,nonclassicality,and quantum coherence,which are sufficient to be used in various one-way quantum technologies,e.g.,invisible quantum sensing,noise-tolerant quantum computing,and chiral quantum networks.Our work provides a general approach to control quantum nonreciprocities with the topological effect,which substantially broadens the fields of nonreciprocal photonics and topological physics.

Quantum dense coding with gravitational cat states

A protocol of quantum dense coding with gravitational cat states is proposed.We explore the effects of temperature and system parameters on dense coding capacity and provide an efficient strategy to preserve the quantum advantage of dense coding for these states.Our results may open new opportunities for secure communication and insights into the fundamental nature of gravity in the context of quantum information processing.

Optomechanical Schrödinger cat states in a cavity Bose-Einstein condensate

Schrödinger cat states,consisting of superpositions of macroscopically distinct states,provide key resources for a large number of emerging quantum technologies in quantum information processing.Here we propose how to generate and manipulate mechanical and optical Schrödinger cat states with distinguishable superposition components by exploiting the unique properties of cavity optomechanical systems based on Bose-Einstein condensate.Specifically,we show that in comparison with its solid-state counterparts,almost a 3 order of magnitude enhancement in the size of the mechanical Schrödinger cat state could be achieved,characterizing a much smaller overlap between its two superposed coherent-state components.By exploiting this generated cat state,we further show how to engineer the quadrature squeezing of the mechanical mode.Besides,we also provide an efficient method to create multicomponent optical Schrödinger cat states in our proposed scheme.Our work opens up a new way to achieve nonclassical states of massive objects,facilitating the development of fault-tolerant quantum processors and sensors.

Properties and Generation of Photon-Added Schrdinger Cat States

We have investigated the intensity squeezing of superposition of two photon-added coherent states and proposed a new method for preparation of photon-added coherent states and their superposition states.This method is based on interaction of the trapped ion with the traveling wave light fields with different frequencies.

光纤孤子的量子特性:压缩态和类薛定谔猫态(Schrdinger-cat-like states)

利用与时间有关的Hartree近似法证明借助非线性Mach-Zehnder干涉仪可以得到光孤子的光子数压缩态<(Δ^N)2>min～<^N>1/3,并且指出在一些特定时刻光纤孤子会呈现出类薛定谔猫态(Schr dinger-cat-likestates)。

The change of dopamine in cerebrospinal fluid and serum in cats with persistent vegetative state

AIM:To investigate the changes and significance of dopamine(DA) in cerebrospinal fluid and serum in the cats with persistent vegetative state(PVS). METHODS:To measure the level of DA in cerebrospinal fluid and serum with high performance liquid chromatography and electrical chemical detect (HPLC ECD) in the cats with PVS and compared with control group.RESULTS:The level of DA in cerebrospinal fluid and serum in the cats with PVS was obviously lower than that of control group.CONCLUSION:Decrease of DA might be one of important factors of PVS formation.

Jaynes-Cummings model with intensity-dependent coupling and Schrbdinger cat state

Linear superposition principle is a basic characteristic of quantum mechanics. The quantum interference of matter wave results from this principle. Recently, considerable effort has been devoted to the study of the properties of superpositions of two or more coherent states, i.e. the Schr(?)dinger cat states.It is shown that the superpositions of coherent states have properties different from those of the coherent state, such as the higher-order squeezing, sub-Poissonian distribution, oscillatory photon statistics and antibunching effect, because of the quantum interference between the components of the cat states. The emergence of these non-classical effects makes the study of the Schr(?)

Preparation of maximally-entangled states with multiple cat-state qutrits in circuit QED

In recent years,cat-state encoding and high-dimensional entanglement have attracted much attention.However,previous works are limited to generation of entangled states of cat-state qubits(two-dimensional entanglement with cat-state encoding),while how to prepare entangled states of cat-state qutrits or qudits(high-dimensional entanglement with cat-state encoding)has not been investigated.We here propose to generate a maximally-entangled state of multiple cat-state qutrits(three-dimensional entanglement by cat-state encoding)in circuit QED.The entangled state is prepared with multiple microwave cavities coupled to a superconducting flux ququart(a four-level quantum system).This proposal operates essentially by the cavity-qutrit dispersive interaction.The circuit hardware resource is minimized because only a coupler ququart is employed.The higher intermediate level of the ququart is occupied only for a short time,thereby decoherence from this level is greatly suppressed during the state preparation.Remarkably,the state preparation time does not depend on the number of the qutrits,thus it does not increase with the number of the qutrits.As an example,our numerical simulations demonstrate that,with the present circuit QED technology,the high-fidelity preparation is feasible for a maximally-entangled state of two cat-state qutrits.Furthermore,we numerically analyze the effect of the inter-cavity crosstalk on the scalability of this proposal.This proposal is universal and can be extended to accomplish the same task with multiple microwave or optical cavities coupled to a natural or artificial four-level atom.

基于CSO-AUKF的锂电池SOC估算方法

电池荷电状态(SOC)估算是电池管理系统(BMS)的关键技术之一。针对锂电池提出了一种基于猫群(CSO)算法和自适应无迹卡尔曼滤波(AUKF)算法相结合的电池SOC估算方法;建立了基于二阶RC等效电路模型的锂电池状态方程,采用CSO算法提高电池辨识精度,联合AUKF算法对SOC进行估算;基于混合脉冲功率测试工况(HPPC)和间歇恒流放电工况下的数据对该方法有效性进行了验证。研究结果表明:基于CSO-AUKF估算,SOC最大误差小于1.64%,估算精度及稳定性均好于遗传算法。

基于扩张状态观测器的过热汽温系统建模与参数智能辨识

可再生能源的高渗透率给电网供需匹配带来严峻挑战的同时,燃煤机组需要承担着大量的调峰调频任务,这对过热汽温系统的安全稳定运行造成了一定威胁,因此有必要建立面向热工控制的汽温数学模型。考虑到迟延型扩张状态观测器(time-delayed extended state observer,TD-ESO)的总扰动信号中含有大量模型信息,提出一种基于ESO补偿模型的参数智能优化和信息提取方法,即以总扰动中未知信息量最小为目标,采用改进沙丘猫算法对模型参数优化并提取总扰动中已知模型信息补偿至ESO的输入端。在仿真算例方面,线性和非线性系统的测试结果表明,所提辨识方法对有无输入迟延的两种系统均有良好的适用性和较高的精度;在实际应用方面,基于超超临界二次再热机组的过热汽温系统数据进行模型辨识与验证,同样表明该建模方法是合理、准确的。因此,该文所建立的模型能够为汽温系统的控制策略设计和性能优化等方面提供有价值的参考。