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161.
162.
We investigate solitary vortex evolution in two-dimensional Bose-Einstein condensates based on the Gross-Pitaevskii equation model. Through the variational method, together with the novel Gaussian ansatz incorporating asymmetric perturbation effects, we arrive at the analytical solitary vortex solution with two typical forms:a symmetric quasi-stable solution under certain parametric settings and a diverging propagation case arising from an initial asymmetric perturbation. The derived pictorial evolutionary patterns of the solitary vortices are compared with those from a pure numerical analysis, and by identifying the key qualitative features, we show the applicability of the theoretical treatment presented here. 相似文献
163.
对偶极玻色-爱因斯坦凝聚体(Bose-Einstein condensate,BEC)在类方势阱中的Bénard-von Kármán涡街现象进行了数值研究.结果表明,当障碍势在BEC中的运动速度与尺寸在适当范围内时,系统中会出现稳定的两列涡旋对阵列,即Bénard-von Kármán涡街.研究了偶极相互作用强弱、障碍势尺寸以及运动速度对尾流中产生的涡旋结构的影响,得到了相图结构.对障碍势所受拖拽力进行计算,分析了涡旋对产生的力学机理. 相似文献
164.
chengp@.com 《原子与分子物理学报》2018,35(6)
基于平均场理论和分裂算符谱算法, 研究了偶极-偶极相互作用下玻色爱因斯坦凝聚体中涡旋的非线性动力学. 研究发现外势运动速度小于临界值时,偶极-偶极相互作用对系统涡旋的非线性动力学影响较小,而外势运动速度超过临界速度时,偶极-偶极相互作用对涡旋的非线性动力学影响很大,可使系统产生涡旋对、涡旋偶极子和简单涡旋,并使它们形成涡街. 相似文献
165.
WANG Tian-Yuan 《理论物理通讯》2009,51(2):255-258
We consider the one-dimensional nonlinear Schrǒdinger equations that describe the dynamics of a Bose-Einstein Condensates with time-dependent scattering length in a complex potential. Our results show that as long as the integrable relation is satisfied, exact solutions of the one-dimensional nonlinear Schrǒdinger equation can be found in a general closed form, and interactions between two solitons are modulated in a complex potential We find that the changes of the scattering length and trapping potential can be effectively used to control the interaction between two bright soliton. 相似文献
166.
Effects of three-body interaction on collective excitation and stability of Bose--Einstein condensate
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This paper investigates the collective excitation and stability of
low-dimensional Bose--Einstein condensates with two- and three-body
interactions by the variational analysis of the time-dependent
Gross--Pitaevskii--Ginzburg equation. The spectrum of the low-energy
excitation and the effective potential for the width of the
condensate are obtained. The results show that: (i) the repulsive
two-body interaction among atoms makes the frequency red-shifted for
the internal excitation and the repulsive or attractive three-body
interaction always makes it blue-shifted; (ii) the region for the
existence of the stable bound states is obtained by identifying the
critical value of the two- and three-body interactions. 相似文献
167.
From the overlap lattice quark propagator calculated in the Landau gauge,we determine the quark chiral condensate by fitting operator product expansion formulas to the lattice data.The quark propagators are computed on domain wall fermion configurations generated by the RBC-UKQCD Collaborations with N_f = 2 + 1flavors.Three ensembles with different light sea quark masses are used at one lattice spacing 1/a = 1.75(4) Ge V.We obtain ψψ (2 GeV)MS =(-304(15)(20) MeV)~3in the SU(2) chiral limit. 相似文献
168.
Jiating Ni Siamak Dadras Wa Kun Lam Rajendra K. Shrestha Mark Sadgrove Sandro Wimberger Gil S. Summy 《Annalen der Physik》2017,529(8)
Quantum‐resonance ratchets have been realized over the last ten years for the production of directed currents of atoms. These non‐dissipative systems are based on the interaction of a Bose‐Einstein condensate with an optical standing wave potential to produce a current of atoms in momentum space. In this paper we provide a review of the important features of these ratchets with a particular emphasis on their optimization using more complex initial states. We also examine their stability close to resonance conditions of the kicking. Finally we discuss the way in which these ratchets may pave the way for applications in quantum (random) walks and matter‐wave interferometry. 相似文献
169.
三维QED 具有两个和QCD类似的性质:动力学手征对称破缺和禁闭。为了研究动力学手征对称破缺,基于彩虹近似,在Dyson-Schwinger 方程框架下,通过迭代求解有限温下的费米子自能方程,讨论了不同的费米速度下费米子手征凝聚与费米子味数之间的关系。发现在有限温下,对于固定的费米子味数,费米手征凝聚随费米速度的变大而单调减小。Analogous to Quantum QCD, QED3 has two interesting features: dynamical chiral symmetry breaking (DCSB) and confinement. By adopting the rainbow approximation, we numerically solve the fermion self-energy equation at finite temperature in the framework of Dyson-Schwinger equations and discuss the relation between chiral condensate and fermion flavor for several fermion velocities in the finite temperature QED3. It is found that the fermion chiral condensate decreases monotonically with the fermion velocity increasing for a fixed N at finite temperature. 相似文献
170.
We investigate a one-dimensional open Bose-Einstein condensate with attractive interaction,by considering the effect of feeding from nonequilibrium thermal cloud and applying the time-periodic inverted-harmonic potential.Using the direct perturbation method and the exact shock wave solution of the stationary Gross-Pitaevskii equation,we obtain the chaotic perturbed solution and the Melnikov chaotic regions.Based on the analytical and the numerical methods,the influence of the feeding strength on the chaotic motion is revealed.It is shown that the chaotic regions could be enlarged by reducing the feeding strength and the increase of feeding strength plays a role in suppressing chaos.In the case of "nonpropagated" shock wave with fixed boundary,the number of condensed atoms increases faster as the feeding strength increases.However,for the free boundary the metastable shock wave with fixed front density oscillates its front position and atomic number aperiodically,and their amplitudes decay with the increase of the feeding strength. 相似文献