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Most of previously reported dark-bright solitons admit identical width for the two components in both theoretical and experimental studies. We report dark-bright solitons can admit strikingly different widths, and derive a family of analytical solutions for them by Lagrangian variational method. The existence regimes for these solitons become much more widespread in the space of nonlinear parameters, than the ones for the previously known dark-bright solitons with identical width. Our analysis indicates that the effective quantum wells are quite different in the two components, in sharp contrast to the ones for all previously known vector solitons. Especially, the particle number of bright soliton can be used to control the generation of dark-bright solitons with varied ratios of solitons' widths. Based on the current experimental technologies, we propose an experimental scheme for observing these novel dark-bright solitons. The results suggest that abundant vector solitons with difference widths exist in multi-components coupled systems, and would inspire experiments to observe them in nonlinear optical fibers, Bose-Einstein condensates, and other nonlinear coupled systems.

While usually the optical diffraction limit is setting a limit for the lengthscales on which a typical alkali Bose-Einstein condensate can be controlled, we show that in certain situations control via matter waves can achieve smaller resolutions. For this we consider a small number of impurity atoms which are trapped inside the density dip of a dark soliton state and show that any grey soliton can be obtained by just driving the impurity atoms. By controlling the driving force on the impurity, one can therefore fully control the position and velocity of the dark soliton, and also study controlled collisions between these non-linear objects., Comment: 7 pages, 6 figures

We systematically investigate rogue wave's spatial-temporal pattern in $N$ $(N\geq2)$-component coupled defocusing nonlinear Schr\"{o}dinger equations. The fundamental rogue wave solutions are given in a unified form for both focusing and defocusing cases. We establish the quantitative correspondence between modulation instability and rogue wave patterns, which develops the previously reported inequality relation into an equation correspondence. As an example, we demonstrate phase diagrams for rogue wave patterns in a two-component coupled system, based on the complete classification of their spatial-temporal structures. The phase diagrams enable us to predict various rogue wave patterns, such as the ones with a four-petaled structure in both components. These results are meaningful for controlling the rogue wave excitations in two orthogonal polarization optical fibers., Comment: 6 pages,2 figures

Dark soliton is usually seen as one of the simplest topological solitons, due to the phase jump across its density dip. We investigate the phase jump properties of dark solitons in a single mode optical fiber with the third-order dispersion and delayed nonlinear response, based on exact analytical solutions of Hirota equation. Our analysis indicates that a single-valley dark soliton (SVDS) can admit two distinct phase jumps at the same velocity, in sharp contrast to the dark soliton with only the second-order dispersion and self-phase modulation, which admits a one-to-one match between the velocity and phase jump. We further uncover the different topological vector potentials underlying the distinct phase jumps. The relations between phase jump and velocity of the SVDS can explain the generation of the previously reported double-valley dark soliton (DVDS). The detailed analysis on the two phase jumps characters of the DVDS with one identical velocity enables us to obtain U-shaped type or double-step type phase distribution. We further explore collision properties of the DVDSs by analyzing their topological phase, which can be considered as the generalization of topological phase (Phys. Rev. E 103, L040204). Strikingly, the inelastic collision can lead to the conversion between the two types of phase distributions for DVDS. The results reveal that inelastic or elastic collision can be judged by analyzing the magnetic monopole fields., Comment: 15 pages, 7 figures

We study the dynamics of Kuznetsov-Ma solitons (KMS) in the framework of vector nonlinear Schr\"odinger (Manakov) equations. Exact multi-parameter family of solutions for such KMSs is derived. This family of solutions includes the known results as well as the previously unknown solutions in the form of the non-degenerate KMSs. We present the existence diagram of such KMSs that follows from the exact solutions. These non-degenerate KMSs are formed by nonlinear superposition of two fundamental KMSs that have the same propagation period but different eigenvalues. We present the amplitude profiles of new solutions, their exact physical spectra, their link to ordinary vector solitons and offer easy ways of their excitation using numerical simulations., Comment: 15 pages, 14 figures

We study the topological phase of bright soliton with arbitrary velocity under the self-steepening effect. Such topological phase can be described by the topological vector potential and effective magnetic field. We find that the point-like magnetic fields corresponds to the density peak of such bright solitons, where each elementary magnetic flux is {\pi}. Remarkably, we show that two bright solitons can generate an additional topological field due to the phase jump between them. Our research provided the possibility to use bright solitons to explore topological properties.

We obtain multivalley dark soliton solutions with asymmetric or symmetric profiles in multicomponent repulsive Bose-Einstein condensates by developing the Darboux transformation method. We demonstrate that the width-dependent parameters of solitons significantly affect the velocity ranges and phase jump regions of multivalley dark solitons, in sharp contrast to scalar dark solitons. For double-valley dark solitons, we find that the phase jump is in the range $[0,2\pi]$, which is quite different from that of the usual single-valley dark soliton. Based on our results, we argue that the phase jump of an $n$-valley dark soliton could be in the range $[0,n\pi]$, supported by our analysis extending up to five-component condensates. The interaction between a double-valley dark soliton and a single-valley dark soliton is further investigated, and we reveal a striking collision process in which the double-valley dark soliton is transformed into a breather after colliding with the single-valley dark soliton. Our analyses suggest that this breather transition exists widely in the collision processes involving multivalley dark solitons. The possibilities for observing these multivalley dark solitons in related Bose-Einstein condensates experiments are discussed.

Dark soliton is one of most interesting nonlinear excitations in physical systems, manifesting a spatially localized density "dip" on a uniform background accompanied with a phase jump across the dip. However, the topological properties of the dark solitons are far from fully understood. Our investigation for the first time uncover a vector potential underlying the nonlinear excitation whose line integral gives the striking phase jump. More importantly, we find that the vector potential field has a topological configuration in analogous to the Wess-Zumino term in a Lagrangian representation. It can induce some point-like magnetic fields scattered periodically on a complex plane, each of them has a quantized magnetic flux of elementary $\pi$. We then calculate the Euler characteristic of the topological manifold of the vector potential field and classify all known dark solitions according to the index., Comment: 6 pages, 3 figures

In this work, we explore systematically various SO(2)-rotation-induced multiple dark-dark soliton breathing patterns obtained from stationary and spectrally stable multiple dark-bright and dark-dark waveforms in trapped one-dimensional, two-component atomic Bose-Einstein condensates (BECs). The stationary states stem from the associated linear limits (as the eigenfunctions of the quantum harmonic oscillator problem) and are parametrically continued to the nonlinear regimes by varying the respective chemical potentials, i.e., from the low-density linear limits to the high-density Thomas-Fermi regimes. We perform a Bogolyubov-de Gennes (BdG) spectral stability analysis to identify stable parametric regimes of these states. Upon SO(2)-rotation, the stable steady-states, one-, two-, three-, four-, and many dark-dark soliton breathing patterns are observed in the numerical simulations. Furthermore, analytic solutions up to three dark-bright solitons in the homogeneous setting, and three-component systems are also investigated., Comment: 14 pages, 12 figures

Dark solitons are common topological excitations in a wide array of nonlinear waves. The dark soliton excitation energy, crucial for exploring dark soliton dynamics, is necessarily calculated in a renormalized form due to its existence on a finite background. Despite its tremendous importance and success, the renormalized energy form was firstly only suggested with no detailed derivation, and was then "derived" in the grand canonical ensemble. In this work, we revisit this fundamental problem and provide an alternative and intuitive derivation of the energy form from the fundamental field energy by utilizing a limiting procedure that conserves number of particles. Our derivation yields the same result, putting therefore the dark soliton energy form on a solid basis., Comment: 4 pages

The recent experimental realization of spin-orbit coupling for ultracold atomic gases opens a new avenue for engineering solitons with internal spatial structures through tuning atomic band dispersions. However, the types of the resulting stripe solitons in a spin-1/2 Bose-Einstein condensate (BEC) have been limited to dark-dark or bright-bright with the same density profiles for different spins. Here we propose that general types of stripe solitons, including magnetic stripe (e.g., dark-bright) and localized stripe waves (neither bright nor dark), could be realized in a spin-1 BEC with widely tunable band dispersions through modulating the coupling between three spin states and the linear momentum of atoms. \ Surprisingly, a moving magnetic stripe soliton can possess both negative and positive effective masses at different velocities, leading to a zero mass soliton at certain velocity. Our work showcases the great potential of realizing novel types of solitons through band dispersion engineering, which may provide a new approach for exploring soliton physics in many physical branches., Comment: 6 pages, 7 figures

We study the relations between solitons of nonlinear Schr\"{o}dinger equation described systems and eigen-states of linear Schr\"{o}dinger equation with some quantum wells. Many different non-degenerated solitons are re-derived from the eigen-states in the quantum wells. We show that the vector solitons for coupled system with attractive interactions correspond to the identical eigen-states with the ones of coupled systems with repulsive interactions. The energy eigenvalues of them seem to be different, but they can be reduced to identical ones in the same quantum wells. The non-degenerated solitons for multi-component systems can be used to construct much abundant degenerated solitons in more components coupled cases. On the other hand, we demonstrate soliton solutions in nonlinear systems can be also used to solve the eigen-problems of quantum wells. As an example, we present eigenvalue and eigen-state in a complicated quantum well for which the Hamiltonian belongs to the non-Hermitian Hamiltonian having Parity-Time symmetry. We further present the ground state and the first exited state in an asymmetric quantum double-well from asymmetric solitons. Based on these results, we expect that many nonlinear physical systems can be used to observe the quantum states evolution of quantum wells, such as water wave tank, nonlinear fiber, Bose-Einstein condensate, and even plasma, although some of them are classical physical systems. These relations provide another different way to understand the stability of solitons in nonlinear Schr\"{o}dinger equation described systems, in contrast to the balance between dispersion and nonlinearity., Comment: 12 pages, 3 figures

The wave properties of solitons in a two-component Bose-Einstein condensates with attractive interactions or repulsive interactions are investigated in detail. We demonstrate that dark solitons in one of component admit interference and tunneling behaviour, in sharp contrast to the scalar dark solitons and vector dark solitons. The analytic analysis of interference properties shows that spatial interference pattern is determined by the relative velocity of solitons, while temporal interference pattern depends on the velocities and widths of two solitons, differing from the interference properties of scalar bright solitons. Especially, for attractive interactions system, we show that interference effects can induce some short-time density humps (whose densities are higher than background density) during the collision process of dark solitons. Moreover, the maximum hump value is remarkably sensitive to the variation of the solitons' parameters. For repulsive interactions system, the temporal-spatial interference periods have lower limits. Numerical simulations results suggest that interference patterns for 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 behaviour can be observed experimentally and could be used to design matter wave soliton interferometry in vector systems.

The properties of nonlinear interference pattern between atomic bright solitons are characterized analytically, with the aid of exact solutions of dynamical equation in mean-field approximation. It is shown that relative velocity, relative phase, and nonlinear interaction strength can be measured from the interference pattern. The nonlinear interference properties are proposed to design atomic soliton interferometry in Bose-Einstein condensate. As an example, we apply them to measure gravity acceleration in a ultra-cold atom systems with a high precision degree. The results are also meaningful for precise measurements in optical fiber, water wave tank, plasma, and other nonlinear systems., Comment: 7 pages, 3 figures

We study the beating effects of solitons in multi-component coupled Bose-Einstein condensate systems. Our analysis indicate that the period of beating behavior is determined by the energy eigenvalue difference in the effective quantum well induced by solitons, and the beating pattern is determined by the eigen-states of quantum well which are involved in the beating behavior. We show that the beating solitons correspond to linear superpositions of eigen-states in some quantum wells, and the correspondence relations are identical for solitons in both attractive interaction and repulsive interaction condensate. This provides a possible way to understand the beating effects of solitons for attractive and repulsive interaction cases in a unified way, based on the knowledge of quantum eigen-states. Moreover, our results demonstrate many different beating patterns for solitons in three-component coupled condensate, in sharp contrast to the beating dark soliton reported before. The beating behavior can be used to test the eigenvalue differences of some certain quantum wells, and more abundant beating patterns are expected to exist in more components coupled systems., Comment: 7 papes, 3 figures

We study breathers and solitons on different backgrounds in optical fiber system, which is governed by generalized coupled Hirota equations with four wave mixing effect. On plane wave background, a transformation between different types of solitons is discovered. Then, on periodic wave background, we find breather-like nonlinear localized waves of which formation mechanism are related to the energy conversion between two components. The energy conversion results from four wave mixing. Furthermore, we prove that this energy conversion is controlled by amplitude and period of backgrounds. Finally, solitons on periodic wave background are also exhibited. These results would enrich our knowledge of nonlinear localized waves' excitation in coupled system with four wave mixing effect.

We study rogue wave excitation dynamics on a double-plane wave background through deriving rogue wave solution on the background. The results indicate that rogue wave still can be excited successfully from resonant perturbations with the two plane wave backgrounds. The obtained vector rogue wave can be decomposed to two rogue waves located on the two backgrounds separately. This enables us to investigate the superpositions of two of the three well-known fundamental rogue wave patterns, mainly including eye-shaped, anti-eye-shaped, and four-petaled one. The explicit conditions for different possible superpositions are clarified by a phase diagram for rogue wave pattern on each plane wave background. The detail analysis indicate that the rogue wave admits many different profiles, in contrast to the ones reported before. The studies can be extended directly to investigate other localized waves on double-plane wave background and even more plane waves involved cases., Comment: 5 pages, 5 figures

We study rogue wave excitation pattern in a two-component Bose-Einstein condensate with pair-transition effects. The results indicate that rogue wave excitation can exist on a stripe phase background for which there are cosine and sine wave background in the two components respectively. The rogue wave peak can be much lower than the ones of scalar matter wave rogue waves, and varies with the wave period changing. Both rogue wave pattern and rogue wave number on temporal-spatial plane are much more abundant than the ones reported before. Furthermore, we prove that the rogue wave number can be $n (n+1)/2+m (m+1)/2$ (where $m,n $ are arbitrary non-negative integers), in contrast to $n(n+1)/2$ for scalar nonlinear Schr\"{o}dinger equation described systems. These results would enrich our knowledge on nonlinear excitations in multi-component Bose-Einstein condensate with transition coupling effects., Comment: 8 pages, 8 figures

We study the correspondence between modulational instability and types of fundamental nonlinear excitation in a nonlinear fiber with both third-order and fourth-order effects. Some stable soliton excitations are obtained in modulational instability regime, which have not been found in nonlinear fibers with second-order effects and third-order effects. Explicit analysis suggests that the stable soliton existence is related with the modulation stability circle in the modulation instability regime, and they just exist in the modulational instability regime outside of the modulational stability circle. It should be emphasized that the stable soliton just exist with two special profiles on a continuous wave background with certain frequency. The evolution stability of the solitons is tested numerically, which indicate they are robust against perturbations even in modulation instability regime. The further analysis indicates that the solitons in modulational instability regime are caused by the fourth-order effects., Comment: 7 pages, 5 figures

We investigate tunneling behavior between two bright solitons in a Bose-Einstein condensate with attractive contact interactions between atoms. The explicit tunneling properties including tunneling particles and oscillation period are described analytically, which indicates that the periodic tunneling form is a nonlinear Josephson type oscillation. The results suggest that the breathing behavior of solitons comes from the tunneling mechanism in an effective double-well potential, which is quite different from the modulational instability mechanism for Akhmediev breather and K-M breather. Furthermore, we obtain a phase diagram for two soliton interaction which admits tunneling property, particle-like property, interference property, and a resonant interaction case. The explicit conditions for them are clarified based on the defined critical distance $d_c$ and spatial interference period $D$., Comment: 8 pages, 7 figures

We study symmetric and asymmetric optical multi-peak solitons on a continuous wave background in the femtosecond regime of a single-mode fiber. Key characteristics of such multi-peak solitons, as the formation mechanism, propagation stability, and shape-changing collisions, are revealed in detail. Our results show that this multi-peak (symmetric or asymmetric) mode could be regarded as a single pulse formed by a nonlinear superposition of a periodic wave and a single-peak (W-shaped or antidark) soliton. In particular, a phase diagram for different types of nonlinear excitations on a continuous wave background including breather, rogue wave, W-shaped soliton, antidark soliton, periodic wave, and multi-peak soliton is established based on the explicit link between exact nonlinear wave solution and modulation instability analysis. Numerical simulations are performed to confirm the propagation stability of the multi-peak solitons with symmetric and asymmetric structures. Further, we unveil a remarkable shape-changing feature of asymmetric multi-peak solitons. It is interesting that these shape-changing interactions occur not only in the intraspecific collision (soliton mutual collision) but also in the interspecific interaction (soliton-breather interaction). Our results demonstrate that each multi-peak soliton exhibits the coexistence of shape change and conservation of the localized energy of light pulse against the continuous wave background., Comment: 9 pages, 8 figures

We study on dynamics of high-order rogue wave in two-component coupled nonlinear Schr\"{o}dinger equations. Based on the generalized Darboux transformation and formal series method, we obtain the high-order rogue wave solution without the special limitation on the wave vectors. As an application, we exhibit the first, second-order rogue wave solution and the superposition of them by computer plotting. We find the distribution patterns for vector rogue waves are much more abundant than the ones for scalar rogue waves, and also different from the ones obtained with the constrain conditions on background fields. The results further enrich and deep our realization on rogue wave excitation dynamics in such diverse fields as Bose-Einstein condensates, nonlinear fibers, and superfluids., Comment: 9 pages, 7 figures

We revisit on rational solution of Sasa-Satsuma equation, which can be used to describe evolution of optical field in a nonlinear fiber with some high-order effects. We find a striking dynamical process which involves both modulational instability and modulational stability regimes, in contrast to the rogue waves and W-shaped soliton reported before which involves modulational instability and stability respectively. It is demonstrated that stable W-shaped solitons can be generated from a weak modulation signal on continuous wave background. This provides a possible way to obtain stable high-intensity pulse from low-intensity continuous wave background.

We find that diverse nonlinear waves, such as soliton, Akhmediev breather, and rogue waves (RWs), can emerge and interplay with each other in a two-mode coupled system. It provides a good platform to study interaction between different kinds of nonlinear waves. In particular, we obtain dark RWs analytically for the first time in the coupled system, and find that two RWs can appear in the temporal-spatial distribution. Possible ways to observe these nonlinear waves are discussed., Comment: 8 pages, 8 figures

We investigate rogue-wave solutions in a three-component coupled nonlinear Schrodinger equation. With certain requirements on the backgrounds of components, we construct a multi-rogue-wave solution that exhibits a structure like a four-petaled flower in temporal-spatial distribution, in contrast to the eye-shaped structure in one-component or two-component systems. The results could be of interest in such diverse fields as Bose-Einstein condensates, nonlinear fibers, and superfluids., Comment: 8 pages, 4 figures

State transition between the Peregrine rogue wave and w-shaped traveling wave induced by higher-order effects and background frequency is studied. We find that this intriguing transition, described by an exact explicit rational solution, is consistent with the modulation instability (MI) analysis that involves MI region and stability region in low perturbation frequency region. In particular, the link between the MI growth rate and transition characteristic analytically demonstrates that, the size characteristic of transition is positively associated with the reciprocal of zero-frequency growth rate. Further, we investigate the case for nonlinear interplay of multi-localized waves. It is interesting that the interaction of second-order waves in stability region features a line structure, rather than an elastic interaction between two w-shaped traveling waves., Comment: 5 pages, 8 figures

We study on the relations between modulational instability and several well-known nonlinear excitations in a nonlinear fiber, such as bright soliton, nonlinear continuous wave, Akhmediev breather, Peregrine rogue wave, and Kuznetsov-Ma breather. We present a quantitative correspondence between them based on the dominant frequency and propagation constant of each perturbation on a continuous wave background. Especially, we find rogue wave comes from modulational instability under the "resonance" perturbation with continuous wave background. These results will deepen our understanding on rogue wave excitation and could be helpful for controllable nonlinear wave excitations in nonlinear fiber and other nonlinear systems., Comment: 5 pages, 1 figure

We present exact rational solution for a modified nonlinear Schr$\ddot{o}$dinger equation that takes into account quintic nonlinearity and nonlinear dispersion corrections to the cubic nonlinearity, which could be used to describe rogue wave in nonlinear fibers. We find the rogue wave with these higher order effects has identical shape with the well-known one in nonlinear Schr$\ddot{o}$dinger equation. However, the quintic nonlinear term and nonlinear dispersion effect affect the velocity of rogue wave, and the evolution of its phase., Comment: 4 pages, 2 figures

We study on dynamics of high-order rogue wave in two-component coupled nonlinear Schr\"{o}dinger equations. We find four fundamental rogue waves can emerge for second-order vector RW in the coupled system, in contrast to the high-order ones in single component systems. The distribution shape can be quadrilateral, triangle, and line structures through varying the proper initial excitations given by the exact analytical solutions. Moreover, six fundamental rogue wave can emerge on the distribution for second-order vector rogue wave, which is similar to the scalar third-order ones. The distribution patten for vector ones are much abundant than the ones for scalar rogue waves. The results could be of interest in such diverse fields as Bose-Einstein condensates, nonlinear fibers, and superfluids., Comment: 5 pages, 4 figures

We study localized wave on continuous wave background analytically in a nonlinear fiber with higher order effects such as higher order dispersion, Kerr dispersion, and stimulated inelastic scattering. We present an exact rational W-shaped soliton solutions, whose structural properties depend on the frequency of the background field. The hump value increase with the decrease of the background frequency in the certain regime. The highest value of the W-shaped soliton can be nine times the background's, and the distribution shape is identical with the one of well-known eyes-shaped rogue wave with its maximum peak. The numerical stimulations indicate that the W-shaped soliton is stable with small perturbations., Comment: 5 pages, 4 figures

We investigate the localized waves of the coupled two-mode nonlinear Schr\"{o}dinger equations with a pair-tunneling term representing strongly interacting particles can tunnel between the modes as a fragmented pair. Facilitated by Darboux transformation, we have derived exact solution of nonlinear vector waves such as bright solitons, Kuznetsov-Ma soliton, Akhmediev breathers and rogue waves and demonstrated their interesting temporal-spatial structures. The phase diagram that demarcates the parameter ranges of the nonlinear waves is obtained. Our results have implications in such diverse fields as Bose-Einstein condensate, nonlinear fibers and super fluids., Comment: 5 pages, 6 figures

Interference patterns associated with soliton-soliton interaction are investigated in detail. We find that the temporal and spatial interference patterns exhibit quite different characteristics. The period of the spatial interference pattern is determined by the relative velocity of the solitons, and the temporal pattern behavior is determined by the peak amplitudes and the kinetic energy of the solitons. Analytical expressions for the periods of the interference patterns are obtained. A method for classifying the nonlinearity of many nonlinear systems is proposed. As an example, we discuss possibilities to observe these properties of solitons in a nonlinear planar waveguide., Comment: 5pages, 4 figures

We study on rational solutions on nonzero background of coupled Sasa-Satsuma equations through Darboux transformation method, which take into account third order dispersion, the term with self-frequency shift, and the term describing self-steepening corrections to the cubic nonlinearity. We find there are some new types of localized waves in the coupled system, such as dark-antidark soliton pair, W-shaped soliton, dark W-shaped soliton, and the combined localized waves of them. The results indicate that there are abundant novel localized waves in the two-mode fiber with these high-order effects, which would inspire experimental realization in the related physical systems., Comment: 10pages, 5 figures

We present a simple representation for arbitrary-order rogue wave solution and study on the trajectories of them explicitly. We find that the global trajectories on temporal-spatial distribution all look like "X" shape for rogue waves. Short-time prediction on rogue wave can be done through measuring the information contained in the initial perturbation twice., Comment: Research paper, 6 pages, 6 figures