非线性Jaynes-Cummings模型的动力学特性

运用密度算符间的距离研究了附加克尔介质依赖强度耦合Jaynes-Cummings模型中原子，场及整个量子系统态的演化规律。在与附加克尔介质单光子Jaynes-Cummings模型相比较的基础上。详细讨论了克尔介质非线性相互作用及初始相干光场的强弱对该模型动力学行为的影响。     

Kraus operator solutions to a fermionic master equation describing a thermal bath and their matrix representation

We solve the fermionic master equation for a thermal bath to obtain its explicit Kraus operator solutions via the fermionic state approach. The normalization condition of the Kraus operators is proved. The matrix representation for these solutions is obtained, which is incongruous with the result in the book completed by Nielsen and Chuang [Quantum Computation and Quantum Information, Cambridge University Press, 2000]. As especial cases, we also present the Kraus operator solutions to master equations for describing the amplitude-decay model and the diffusion process at finite temperature.     

New approach for obtaining the time-evolution law of a chaotic light field in a damping-gaining process

A new approach for studying the time-evolution law of a chaotic light field in a damping-gaining coexisting process is presented.The new differential equation for determining the parameter of the density operator ρ(t) is derived and the solution of f ’ for the damping and gaining processes are studied separately.Our approach is direct and the result is concise since it is not necessary for us to know the Kraus operators in advance.     

Kerr介质腔中非关联双模热光场与V型三能级原子相互作用中的场关联特性

研究了Kerr介质腔中非关联双模热光场与V型三能级原子相互作用过程中的场关联特性.通过数值计算和图形分析,讨论了平均光子数、Kerr介质、失谐量以及耦合系数对场的关联特性的影响.结果发现:当V型三能级原子与两模光场发生相互作用时,非关联双模热光场将发生关联,且关联强度与耦合强度、失谐量和Kerr系数有关.当两模热光场和裸原子发生对称相互作用时,两模光场始终处于正关联;增加一模光场的平均光子数,两模光场的关联减弱;Kerr介质和失谐量的增加将削弱两模场的关联;当两模光场与原子发生不对称相互作用时,假设g1>g2,两模光场的关联特性在正关联和反关联之间交替出现.保持场一模的平均光子数不变,增加场另一模的平均光子数,反关联特性消失.     

New approach for obtaining the time-evolution law of chaotic light field in damping—gaining process

A new approach for studying the time-evolution law of chaotic light field in damping-gaining coexisting process is presented. The new differential equation for determining the parameter of the density operator ρ(t) is derived and the solution of f′ for damping and gaining processes are studied separately. Our approach is direct and the result is concise since it is not necessarily for us to know the Kraus operators in advance.     

Infinite-dimensional Kraus operators for describing amplitude-damping channel and laser process

Based on the preceding Communication (Hong-yi Fan, Li-yun Hu, Opt. Commun. 281 (2008) 5571) we identify the explicit infinite-dimensional Kraus operators for describing amplitude-damping channel and for laser process, the normalization of Kraus operators are proved. The evolution of an initial pure coherent state into a mixed state in the laser process is clearly shown by virtue of the explicit operator-sum representation of the Kraus operator.     

Generalized Kraus Operators for the One-Qubit Depolarizing Quantum Channel

Microscopic Hamiltonian models of the composite system “open system + environment” typically do not provide the operator-sum Kraus form of the open system’s dynamical map. With the use of a recently developed method (Andersson et al. J. Mod. Opt. 54, 1695 2007), we derive the Kraus operators starting from the microscopic Hamiltonian model, i.e., from the proper master equation, of the one-qubit depolarizing channel. Those Kraus operators generalize the standard counterparts, which are widely used in the literature. Comparison of the standard and the here obtained Kraus operators is performed via investigating dynamical change of the Bloch sphere volume, entropy production, and the open system’s state trace distance. We compare the generalized with the standard Kraus operators for both single qubit and regarding the occurrence of the entanglement sudden death for a pair of initially correlated qubits. We find that the generalized Kraus operators describe the less deteriorating quantum channel than the standard ones.     

附加克尔介质简并双光子J-C模型的动力学特性

本文利用密度算符间的距离研究了附加克尔介质简并双光子Jaynes－Cummings模型（JCM）的动力学特性．在与标准简并双光子Jaynes－Cummiungs模型以及附加克尔介质单光子Jaynes－Cummings模型相比较的基础上，详细讨论了克尔介质非线性相互作用对该模型动力学行为的影响．     

Entropy squeezing and atomic inversion in the K-photon Jaynes–Cummings model in the presence of the Stark shift and a Kerr medium:A full nonlinear approach

The interaction between a two-level atom and a single-mode field in the k-photon Jaynes–Cummings model(JCM) in the presence of the Stark shift and a Kerr medium is studied. All terms in the Hamiltonian, such as the single-mode field, its interaction with the atom, the contribution of the Stark shift and the Kerr medium effects are considered to be f-deformed.In particular, the effect of the initial state of the radiation field on the dynamical evolution of some physical properties such as atomic inversion and entropy squeezing are investigated by considering different initial field states(coherent, squeezed and thermal states).     

热透镜效应下的克尔透镜锁模

讨论了在增益介质与克尔介质分离情况下热透镜效应对克尔透镜锁模的影响，计算了克尔透镜锁模在热不敏感腔中需满足的条件，结果表明，通过适当地调整激光腔参数，有可能实现热不敏感的克尔透镜锁模。最后通过计算机数值模拟获得了对典型振荡腔设计参量的修正。     

Influence of Kerr Medium on Entanglement of Cascade-Type Three-Level Atoms and a Bimodal Cavity Field

We investigate the influence of Kerr medium on atomic population probability and residual entanglement of the system which consists of cascade-type three-level atoms and a bimodal cavity field filled with Kerr medium. The results show that the period of residual entanglement is shortened and the value of residual entanglement is enhanced by appropriately adjusting the nonlinear Kerr constant. Furthermore, we also study the influence of Kerr medium on entanglement evolution of the two atoms, and find that it decreases the value of entanglement between two atoms.     

附加克尔介质简并双光子J-C模型的动力学特性

本文利用密度算符间的距离研究了附加克尔介质简并双光子Jaynes-Cummings模型(JCM)的动力学特性.在与标准简并双光子Jaynes-Cummiungs模型以及附加克尔介质单光子Jaynes-Cummings模型相比较的基础上,详细讨论了克尔介质非线性相互作用对该模型动力学行为的影响.     

Entropy evolution properties in a system of two entangled atoms interacting with light field

In this paper, we use the field entropy as a measurement of the degree of entanglement between the light field and the atoms of the system which is composed of two dipole—dipole interacting two-level atoms initially in an entangled state interacting with the single mode coherent field in a Kerr medium. The influence of the coupling constant of dipole—dipole interaction between atoms and the coupling strength of the Kerr medium with the light field and the intensity of the light field on the field entropy are discussed by numerical calculations. It is shown that when the coupling strength of the Kerr medium with the light field is large enough, and the light field is strong, the degree of entanglement between the atoms with the light field becomes weaker. The degree of entanglement only changes slightly with the change of the coupling constant of dipole—dipole interaction between atoms.     

Solitons and collapse suppression due to parametric interaction in bulk Kerr media

We demonstrate that weak parametric interaction of a fundamental beam with its harmonic field in a Kerr medium can drastically modify the beam dynamics, giving rise to very complex bifurcation phenomena and quasi solitons. Most importantly, we reveal a novel physical mechanism of the collapse suppression in a bulk optical Kerr medium: parametric coupling to a weakly radiating harmonic field.     

Spectrum of the Micromaser with Kerr Medium

We have established the master equation for the micromaser with Kerr medium field density operator,studied the spectrum of the micromaser with Kerr medium and analyzed the influence of Kerr effect and the detuning onthe spectrum. In the thermal-atom regime, we find that Kerr effect broadens linewidth D and increases frequency-shiftS, and that the detuning A narrows linewidth D and increases frequency-shift S as a whole. Moreover Kerr effect leadsto oscillatings more rapidly in the resonance peaks, which means that it causes quantum noise. As a whole, with theincrease of cavity-length L, the linewidth D and frequency-shift S gradually increase.     

Expectation Value Theorem for Thermo Vacuum States of Optical Chaotic Field and Negative-Binomial Field

For the density operator (mixed state) describing chaotic light and negative-binomial field there exist the corresponding thermal vacuum state (pure state) in the real-fictitious space. Using the method of integration within ordered product of operators we find the expectation value theorem in these two thermo vacuum states respectively. The thermal average theorem of translation operator is also deduced. Application of the new thermo vacuum state in calculating photon number disturibution and fluctuation and thermal average is presented.     

Kraus Operators for a Pair of Interacting Qubits: a Case Study

The Kraus form of the completely positive dynamical maps is appealing from the mathematical and the point of the diverse applications of the open quantum systems theory. Unfortunately, the Kraus operators are poorly known for the two-qubit processes. In this paper, we derive the Kraus operators for a pair of interacting qubits, while the strength of the interaction is arbitrary. One of the qubits is subjected to the x-projection spin measurement. The obtained results are applied to calculate the dynamics of the entanglement in the qubits system. We obtain the loss of the correlations in the finite time interval; the stronger the inter-qubit interaction, the longer lasting entanglement in the system.     

非线性Tavis-Cummings模型的Pancharatnam相(英文)

对处于相干态光场的非线性Tavis-Cummings模型中Pancharatnam相进行了理论上和数值上的研究,并获得了这个量子系统中Pancharatnam相的精确表达式.分析表明:两原子之间的偶极相互作用强度能改变Pancharatnam相演化的周期,并证明了Pancharatnam相包含原子和场的信息,同时,非线性的出现会导致Pancharatnam相的演化出现混沌行为.     

Dynamics of extended bodies with spin-induced quadrupole in Kerr spacetime: generic orbits

We discuss motions of extended bodies in Kerr spacetime by using Mathisson–Papapetrou–Dixon equations. We firstly solve the conditions for circular orbits, and calculate the orbital frequency shift due to the mass quadrupoles. The results show that we need not consider the spin-induced quadrupoles in extreme-mass-ratio inspirals for space-based gravitational wave detectors. We quantitatively investigate the temporal variation of rotational velocity of the extended body due to the coupling of quadrupole and background gravitational field. For generic orbits, we numerically integrate the Mathisson–Papapetrou–Dixon equations for evolving the motion of an extended body orbiting a Kerr black hole. By comparing with the monopole–dipole approximation, we reveal the influences of quadrupole moments of extended bodies on the orbital motion and chaotic dynamics of extreme-mass-ratio systems. We do not find any chaotic orbits for the extended bodies with physical spins and spin-induced quadrupoles. Possible implications for gravitational wave detection and pulsar timing observation are outlined.     

Kerr介质中J-C模型的色散近似耗散动力学

应用全量子论研究了含Kerr介质的Jaynes-Cummings模型在色散近似下系统和子系统的相干性丢失及纠缠特性,在输入场为相干场假设下计算了线性熵.结果表明,原子相干性丢失与Kerr效应无关,场和原子-场系统的相干性丢失因Kerr介质的存在而增强,原子与场之间的纠缠因Kerr效应而受到压制,场的相干性时间演化规律在定性和定量两方面都受到腔耗的影响.Kerr介质对场线性熵的作用要通过腔耗才能展现出来.