Reflection-Transmission Transition of Bright-Bright Solitons Collision in Two Species Condensates with Repulsive Interspecies Interactions

Considering repulsive interspecies interactions,we study the dynamical properties of bright-bright solitons in two species Bose-Einstein condensates by using a variational approach combined with numerical simulation.It is shown that the interactions between bright-bright solitons vary from repulsive to attractive interactions with the increasing their separating distances,and at equilibrium position the bright-bright solitons are localized.Interestingly,a transition from reflection-to transmission-collision is firstly observed,different from previous results of only reflection collision appearing there.These results will be helpful for the experimental manipulating such solitons.     

二元玻色-爱因斯坦凝聚体中矢量孤子的转化行为

考虑种内和种间相互作用均为排斥作用,研究了局限于谐振外部势阱中的二元玻色-爱因斯坦凝聚体中灰-灰和黑-黑孤子的动力学行为.结果表明:当谐振势阱的轴向囚禁频率为零时,灰-灰和黑-黑孤子均能保持局域稳定;而当轴向囚禁频率不为零时,凝聚体中的原子向势阱中心聚集,发现灰-灰孤子可以转化成亮-亮孤子.     

双光子光折变晶体中两分量矢量空间孤子

为了研究外加偏压双光子光折变晶体中的矢量空间孤子,建立了矢量空间孤子的动态演化方程,给出了矢量空间孤子数值解.采用数值模拟的方法,求解矢量空间孤子的数值表达式,理论预言了稳态条件下亮-亮、暗-暗自耦合矢量空间孤子的存在|同时,数值求解演化方程,分析了亮-亮自耦合矢量空间孤子的演化特性.数值结果表明,无论两孤子分量的强度近似相等还是有较大差别,这些自耦合矢量空间孤子都可以由数值积分程序给出.亮-亮、暗-暗自耦合矢量空间孤子在双光子光折变晶体中稳定存在.     

双光子光折变晶体中两分量矢量空间孤子(英文)

为了研究外加偏压双光子光折变晶体中的矢量空间孤子,建立了矢量空间孤子的动态演化方程,给出了矢量空间孤子数值解.采用数值模拟的方法,求解矢量空间孤子的数值表达式,理论预言了稳态条件下亮-亮、暗-暗自耦合矢量空间孤子的存在;同时,数值求解演化方程,分析了亮-亮自耦合矢量空间孤子的演化特性.数值结果表明,无论两孤子分量的强度近似相等还是有较大差别,这些自耦合矢量空间孤子都可以由数值积分程序给出.亮-亮、暗-暗自耦合矢量空间孤子在双光子光折变晶体中稳定存在.     

光晶格势阱中二元凝聚体的矢量孤子的振荡和分裂

考虑外部囚禁势阱为光晶格势阱,研究了二元玻色-爱因斯坦凝聚体中亮-亮孤子的动力学行为.结果表明,亮-亮孤子的运动方向和振荡行为可以分别通过调节光晶格势阱的晶格常数和势阱深度来控制.进一步地,亮-亮孤子还可以被局域在光晶格势阱中,并且随着势阱深度的增加,局域孤子会产生分裂行为.     

双色光光伏空间孤子的形成条件及其应用

以折射率改变为正的光伏晶体为例，讨论在其中形成双色光光伏空间孤子的条件-一般而言，在满足上述条件的情况下，双色光可以形成双色光亮孤子、双色光暗孤子、一亮一暗孤子-对于一个波长的光（ray2）单独不能形成亮孤子（它的Glass系数与背景光的Glass系数之比R2小于１）的情况，如果再加上一束另一个波长的光（ray1），且其Glass系数与背景光的Glass系数之比R1大于１，则在一定条件下，这个双色光中两个颜色的光可以都形成亮孤子-还讨论了ray1的光强对孤子宽度的影响- 关键词： 双色光 光伏 空间孤子 全光开关     

Moving Matter-Wave Solitons in Spin-Orbit Coupled Bose-Einstein Condensates

We investigate the moving matter-wave solitons in spin-orbit coupled Bose-Einstein condensates(BECs) by a perturbation method.Starting with the one-dimensional Gross-Pitaevskii equations,we derive a new KdV-like equation to which an approximate solution is obtained by assuming weak Raman coupling and strong spinorbit coupling.The derivation of the KdV-like equation may be useful to understand the properties of solitons excitation in spin-orbit coupled BECs.We find different types of moving solitons:dark-bright,bright-bright and dark-dark solitons.Interestingly,moving dark-dark soliton for attractive intra- and inter-species interactions is found,which depends on the Raman coupling.The amplitude and velocity of the moving solitons strongly depend on the Raman coupling and spin-orbit coupling.     

Vector Solitons and Soliton Collisions in Two-Component Bose-Einstein Condensates

With realistic parameters, both analytical and computational studies demonstrate the feasibility of forming bright-bright vector solitons in a self-repulsive two-component Bose-Einstein condensate with attractive intercomponent interaction. Moreover, the stability of such solitons is confirmed by direct numerical simulations, by a Bogoliubov spectrum analysis, and by examining the collisions between two vector solitons. Our results are of considerable experimental interest.     

Formation of bright matter-wave solitons during the collapse of attractive Bose-Einstein condensates

We observe bright matter-wave solitons form during the collapse of (85)Rb condensates in a three-dimensional (3D) magnetic trap. The collapse is induced by using a Feshbach resonance to suddenly switch the atomic interactions from repulsive to attractive. Remnant condensates containing several times the critical number of atoms for the onset of instability are observed to survive the collapse. Under these conditions a highly robust configuration of 3D solitons forms such that each soliton satisfies the condition for stability and neighboring solitons exhibit repulsive interactions.     

Matter-Wave Solitons in Two-Component Bose-Einstein Condensates with Tunable Interactions and Time Varying Potential

We present three families of exact matter-wave soliton solutions for an effective one-dimension two-component Bose-Einstein condensates (BECs) with tunable interactions, harmonic potential and gain or loss term.We investigate the dynamics of bright-bright solitons, bright-dark solitons
and dark-dark solitons for the time-dependent expulsive harmonic trap potential,periodically modulated harmonic trap potential, and kinklike modulated harmonic trap potential.Through the Feshbach resonance, these dynamics can be realized in experiments by suitable control of time-dependent trap parameters, atomic interactions, and interaction with thermal cloud.     

飞秒暗孤子间相互作用的数值研究

通过数值模拟对飞秒暗孤子间的相互作用进行了研究，并且同飞秒亮孤子和皮秒暗孤子分别进行了比较，结果表明：同飞秒亮孤子相比，飞秒暗孤子间的相互作用比较小，前者表现为相互吸引、碰撞、合二为一，然后相互排斥，不具有周期性；而后者从一开始就相互排斥，且这种排斥作用较亮孤子来说相当微弱，同样也不具有周期性。此外，数值模拟的结果还表明，飞秒暗孤子间的相互作用同皮秒尺度下暗孤子间的相互作用基本一致，并且通过计算表明，飞秒暗孤子间的相互作用在一定范围内仍可利用皮秒尺度下暗孤子间相互作用的经验公式。但是，数值模拟结果显示，两孤子的初始间距越小，由经验公式计算结果所带来的误差就越大。     

Interactions between Components of Various Vector Solitons in Bose-Einstein Condensates

We investigate the interactions between components of various vector solitons in Bos-Einstein condensates by means of the least action principle, and derive the effective potentials for different vector solitons, which indicate that the interactions are of short range, and may be repulsive or attractive decided by the different intra- and inter-species interactions in such a system. In the case of attraction, the two solitons will oscillate about and pass through each other around the equilibrium state. The comparison of analytical results with mumertical simulation is presented.     

Solitons in Bose–Einstein condensates

The Gross–Pitaevskii equation (GPE) describing the evolution of the Bose–Einstein condensate (BEC) order parameter for weakly interacting bosons supports dark solitons for repulsive interactions and bright solitons for attractive interactions. After a brief introduction to BEC and a general review of GPE solitons, we present our results on solitons that arise in the BEC of hard-core bosons, which is a system with strongly repulsive interactions. For a given background density, this system is found to support both a dark soliton and an antidark soliton (i.e., a bright soliton on a pedestal) for the density profile. When the background has more (less) holes than particles, the dark (antidark) soliton solution dies down as its velocity approaches the sound velocity of the system, while the antidark (dark) soliton persists all the way up to the sound velocity. This persistence is in contrast to the behaviour of the GPE dark soliton, which dies down at the Bogoliubov sound velocity. The energy–momentum dispersion relation for the solitons is shown to be similar to the exact quantum low-lying excitation spectrum found by Lieb for bosons with a delta-function interaction.     

Photovoltaic spatial soliton pairs in two-photon photorefractive materials

We report the existence of incoherently coupled bright-bright steady state photovoltaic soliton pairs in two-photon photorefractive material under open circuit conditions. Based on WKBJ method and paraxial ray approximation, we have obtained coupled equations describing dynamical evolution of spatial soliton pairs. In the steady state regime, the present analysis leads to the identification of existence equation of bright-bright solitons, which captures a plethora of soliton pairs. We have undertaken linear stability analysis which shows that these solitons are stable.     

Combined periodic wave and solitary wave solutions in two-component Boseben Einstein condensates

In this paper, the Jacobi elliptic function expansion method provides an effective approach to obtain the exact periodic wave solutions of two-component Bose-Einstein condensates. Exact combined bright-bright and dark-dark soliton wave solutions can be achieved in their limit conditions. We also obtain the different formation regions of combined solitons. Our results show that the intraspecies (interspecies) interaction strengths clearly affect the formation of dark-dark, bright-bright and dark-bright soliton solutions in different regions.     

Superposition solitons in two-component Bose-Einstein condensates

We develop the Hirota bilinear method and obtain the exact one and two superposition soliton solutions for two-component Bose-Einstein condensates. The conversion of three kinds of solitons including the superposition solitons, bright-bright solitons, and dark-bright solitons is discussed. With the energy analysis, we find that the superposition soliton state is an excitation state for this system. Moreover, the collision of two superposition solitons is found to be elastic.     

One-dimensional optical bright screening photovoltaic photorefractive solitons, soliton pairs and incoherent interaction between them in BaTiO3 crystal

By the use of theory of optical solitons, nonlinear equations governed by screening photorefractive photovoltaic solitons are introduced. By means of numerical methods, intensity profile, refractive index change of the media and also stability under propagation are investigated. Self-bending of solitons under first-order diffusion is also studied. Besides, incoherent coupled bright-bright soliton pairs and incoherent interaction are studied.     

Interference properties of two-component matter wave solitons

Wave properties of solitons in a two-component Bose-Einstein condensate are investigated in detail.We demonstrate that dark solitons in one of components admit interference and tunneling behavior,in sharp contrast to the scalar dark solitons and vector dark solitons.Analytic analyses of interference properties show that spatial interference patterns are determined by the relative velocity of solitons,while temporal interference patterns depend on the velocities and widths of two solitons,differing from the interference properties of scalar bright solitons.Especially,for an attractive interactions system,we show that interference effects between the two dark solitons can induce some short-time density humps(whose densities are higher than background density).Moreover,the maximum hump value is remarkably sensitive to the variation of the solitons' parameters.For a repulsive interactions system,the temporal-spatial interference periods of dark-bright solitons have lower limits.Numerical simulation results suggest that interference patterns for the dark-bright solitons are more robust against noises than bright-dark solitons.These explicit interference properties can be used to measure the velocities and widths of solitons.It is expected that these interference behaviors can be observed experimentally and can be used to design matter wave soliton interferometer in vector systems.     

Interactions between bright solitons in different species of Bose—Einstein condensates

The dynamics of a bright-bright vector soliton in a cigar-shaped Bose-Einstein condensate trapping in a harmonic potential is studied.The interaction between bright solitons in different species with small separation is derived.Unlike the interaction between solitons of the same species,it is independent of the phase difference between solitons.It may be of attraction or repulsion.In the former case,each soliton will oscillate about and pass through each other around the mass-center of the system,which will also oscillate harmonically due to the harmonic trapping potential.     

Slow vector optical solitons in a cold four-level inverted-Y atomic system

The authors show the formation of slow temporal vector optical solitons in a cold lifetime-broadened four-level inverted-Y atomic system. We demonstrate that Maxwell’s equations for describing two orthogonally polarised components of a low intensity signal field can evolve into two coupled nonlinear Schr?dinger equations, which results in various distortion-free temporal vector optical solitons, such as bright-bright or dark-dark vector solitons. These results are produced from the correct balance between dispersion, self- and cross-phase modulation (SPM and XPM) effects. We also show that the integrable Manakov model can be realised by adjusting the corresponding SPM, XPM and dispersion effects of this inverted-Y atomic system.