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Inflationary dynamics in the braneworld scenarios

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Chinese physics B 2013年第5期22卷 669-673页

作者：张开源吴普训余洪伟 Center of nonlinear Science and Department of physics Ningbo University

We analyze the attractor behaviour of the inflation field in braneworld scenarios using the Hamilton-Jacobi formalism, where the Friedmann equation has the form of H2 = ρ + ε(2ρ0ρ)1/2or H2 = ρ + ερ2/2σ , with ε = ±1. We find that in all models the linear homogeneous perturbation can decay exponentially as the scalar field rolls down its potential. However, in the case of a -ρ2 correction to the standard cosmology with ρ 1. Our results show that the perturbation decays more quickly in models with positive-energy correction than in the standard cosmology, which is opposite to the case of negative-energy correction. Thus, the positive-energy modification rather than the negative one can assist the inflation and widen the range of initial conditions.

关键词： inflation braneworld attractor

Vortical Solitons of Three-Dimensional Bose-Einstein Condensates under Both a Bichromatic Optical Lattice and Anharmonic Potentials

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Chinese physics Letters 2013年第6期30卷 29-33页

作者： LI Feng-Bo ZONG Feng-De WANG Ying Institute of nonlinear physics Zhejiang Normal UniversityJinhua 321004

We study Bose–Einstein condensate vortical solitons under both a bichromatic optical lattice and anharmonic *** vortical solitons are built in the form of a layer-chain structure made up of two fundamental vortices along the bichromatic optical lattice direction,which have not been reported before in the three-dimensional Bose–Einstein condensate.A variation approach is applied to find the optimum initial solutions of vortical *** stabilities of the vortical solitons are confirmed by the numerical simulation of the time-dependent Gross–Pitaevskii *** particular,stable Bose–Einstein condensate vortical solitons with fundamental vortices of different atomic numbers in the external potential within a range of experimentally achievable timescales are *** further manipulate the vortical solitons to an arbitrary position by steadily moving the bichromatic optical lattice,and find a stable region for the successful manipulation of vortical solitons without *** results provide insight into controlling and manipulating the Bose–Einstein condensate vortical solitons for macroscopic quantum applications.

关键词： equation. Einstein solitons

Dynamic stability and manipulation of bright matter-wave solitons by optical lattices in Bose-Einstein condensates

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Chinese physics B 2012年第2期21卷 98-106页

作者： Song Chang-Sheng Li Jing Zong Feng-De Institute of nonlinear physics Zhejiang Normal UniversityJinhua 321004China

An extended variation approach to describing the dynamic evolution of self-attractive Bose-Einstein condensates is developed. We consider bright matter-wave solitons in the presence of a parabolic magnetic potential and a timespace periodic optical lattice. The dynamics of condensates is shown to be well approximated by four coupled nonlinear differential equations. A noteworthy feature is that the extended variation approach gives a critical strength ratio to support multiple stable lattice sites for the condensate. We further examine the existence of the solitons and their stabilities at the multiple stable lattice sites. In this case, the analytical predictions of Bose-Einstein condensates variational dynamics are found to be in good agreement with numerical simulations. We then find a stable region for successful manipulating matter-wave solitons without collapse, which are dragged from an initial stationary to a prescribed position by a moving periodic optical lattice.

关键词： Bose-Einstein condensates Gross-Pitaevskii equation matter-wave solitons controlled manipulation

Controlled Manipulation with a Bose-Einstein Condensates N-Soliton Train under the Influence of Harmonic and Tilted Periodic Potentials

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Chinese physics Letters 2008年第7期25卷 2370-2373页

作者：宗丰德张解放 Institute of nonlinear physics Zhejiang Normal University Jinhua 321004

A model of the perturbed complex Toda chain （PCTC） to describe the dynamics of a Bose-Einstein condensate （BEC） N-soliton train trapped in an applied combined external potential consisting of both a weak harmonic and tilted periodic component is first developed. Using the developed theory, the BEC N-soliton train dynamics is shown to be well approximated by 4N coupled nonlinear differential equations, which describe the fundamental interactions in the system arising from the interplay of amplitude, velocity, centre-of-mass position, and phase. The simplified analytic theory allows for an efficient and convenient method for characterizing the BEC N-soliton train behaviour. It further gives the critical values of the strength of the potential for which one or more localized states can be extracted from a soliton train and demonstrates that the BEC N-soliton train can move selectively from one lattice site to another by simply manipulating the strength of the potential.

关键词： OPTICAL LATTICES TUNNEL ARRAYS WAVE SYSTEMS PROPAGATION STABILITY DYNAMICS VORTEX GASES CHAOS

Stable striped state in a rotating two-dimensional spin–orbit coupled spin-1/2 Bose–Einstein condensate

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Communications in Theoretical physics 2022年第7期74卷 114-122页

作者： Xuan Xu Chao Gao Ji Lin Hui-jun Li Institute of nonlinear physics and Department of physics Zhejiang Normal UniversityJinhua 321004China

We consider an effective two-dimensional Bose–Einstein condensate with some spin–orbit coupling(SOC) and a rotation term in an external harmonic potential. We find the striped state,and analyze the effects of SOC, the external potential, and the rotation frequency/direction on the profile and the stability of the striped state. Without the rotation term, the two spinor components exhibit striped pattern, and the numbers of stripes in the two components are always an odd–even or an even–odd. With the increase of the SOC strength, the number of stripes in both components increases, while the difference of the striped numbers is always one. After adding the rotation term, the profiles of the spinor components change qualitatively, and the change regulation of the striped numbers differs, while the difference of the striped numbers is still one. In addition, we find that the rotation direction only makes the striped state of the two spinor components exchange each other, though the clockwise and counterclockwise rotation directions are inequivalent with the presence of SOC. Such regulation is different from the previous study. And the rotation frequency gives rise to the transition from the striped state to a mixture of the striped state and vortex state. Furthermore, we prove the stability of these states by the evolution and linear stability analysis.

关键词： spin-orbit coupling Bose-Einstein condensate the striped state

Exciting rogue waves, breathers, and solitons in coherent atomic media

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Communications in Theoretical physics 2020年第7期72卷 21-29页

作者： Zhong-Yin Li Fei-Feng Li Hui-Jun Li Institute of nonlinear physics and Department of physics Zhejiang Normal UniversityJinhua 321004China

We propose a scheme that excites rogue waves via electromagnetically induced transparency(EIT),which can also excite breathers and *** system is a resonantΛ-type atomic *** EIT conditions,the envelope equation of the probe field can be reduced to several different models,such as the saturable nonlinear Schr?dinger equation(SNLSE),and SNLSE with the trapping potential provided by a far-detuned laser field or a magnetic *** this scheme,rogue waves can be generated by different initial pulses,such as the Gaussian wave with(or without)the uniform *** scheme can be used to obtain rogue waves,breathers and *** show the existence regions of rogue waves,breathers,and solitons as the function of the amplitude and width of the initial *** novelty of our paper is that,we not only show rogue waves in the integrable system numerically,but also present the method to generate and control rogue waves in the non-integrable system.

关键词： electromagnetically induced transparency rogue wave the non-integrable model

Influence of velocity spatiotemporal correlations on the anomalous scaling exponents of passive scalars

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Chinese physics B 2009年第12期18卷 5117-5122页

作者：张晓强王光瑞陈式刚 Graduate School of China Academy of Engineering physics Center for nonlinear Studies Institute of Applied Physics and Computational Mathematics

In this paper, we consider spatial-temporal correlation functions of the turbulent velocities. With numerical simulations on the Gledzer-Ohkitani-Yamada （GOY） shell model, we show that the correlation function decays exponentially. The advecting velocity field is regarded as a colored noise field, which is spatially and temporally correlative. For comparison, we are also given the scaling exponents of passive scalars obtained by the Gaussian random velocity field, the multi-dimensional normal velocity field and the She-Leveque velocity field, introduced by She, et al. We observe that extended self-similarity sealing exponents H（p）/H（2） of passive scalar obtained by the colored noise field are more anomalous than those obtained by the other three velocity fields.

关键词： shell models passive scalar anomalous scaling exponents

Multidimensional System of Ferro-magnetic Chain Type~*

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Science China Mathematics 1993年第12期36卷 1422-1434页

作者：周毓麟孙和生郭柏灵 Centre for nonlinear Studies Institute of Applied Physics and Computational Mathematics

The global solvability of homogeneous boundary problem for a class of multidimensional generalized system of ferro-magnetic chain type is considered.

关键词： multidimensional system of ferro-magnetic chain type spin system homogeneous boundary problem Galerkin’s method.

Explicit Soliton and Periodic Solutions to Three-Wave System with Quadratic and Cubic nonlinearities

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Communications in Theoretical physics 2011年第4期55卷 676-680页

作者：林机赵丽娜李画眉 Institute of nonlinear physics Zhejiang Normal University International Centre for Theoretical physics

Lie group theoretical method and the equation of the Jacobi elliptic function are used to study the three wave system that couples two fundamental frequency （FF） and a single second harmonic （SH） one by competing X^（2）（quadratic） and X^（3）（cubic） nonlinearities and birefringence. This system shares some of the nice properties of soliton system. On the phase-locked condition; we obtain large families of analytical solutions as the soliton, kink and periodic solutions of this system.

关键词： optical soliton Lie group symmetry competing nonlinearity