We simulate the dissipative evolution of a vortex in a trapped finite-temperature dilute-gas Bose-Einstein condensate using first-principles open-systems theory. Simulations of the complete stochastic projected Gross-Pitaevskii equation for a partially condensed Bose gas containing a single quantum vortex show that the transfer of condensate energy to the incoherent thermal component without population transfer provides an important channel for vortex decay. For the lower temperatures considered, this effect is significantly larger that the population transfer process underpinning the standard theory of vortex decay, and is the dominant determinant of the vortex lifetime. A comparison with the Zaremba-Nikuni-Griffin kinetic (two-fluid) theory further elucidates the role of the particle transfer interaction, and suggests the need for experimental testing of reservoir interaction theory. The dominance of this particular energetic decay mechanism for this open quantum system should be testable with current experimental setups, and its observation would have broad implications for the dynamics of atomic matter waves and experimental studies of dissipative phenomena.
We study quantum vortex states consisting of a ring of vortices with alternating sign, in a homogeneous superfluid confined to a circular domain. We find an exact stationary solution of the point vortex model for the neutral vortex necklace. We investigate the stability of the necklace state within both the point-vortex model and the Gross-Pitaevskii equation describing a trapped atomic Bose-Einstein condensate at low temperature. The point-vortex stationary states are found to also be stationary states of the Gross-Pitaevskii equation provided the finite thickness of the outer fluid boundary …
Instabilities of vortex-ring-bright coherent structures in harmonically trapped two-component three-dimensional Bose-Einstein condensates are studied numerically within the coupled Gross-Pitaevskii equations and interpreted analytically. Interestingly, the filled vortex core with a sufficiently large amount of the bright component is observed to reduce the parametric interval of stability of the vortex ring. We have identified the mechanisms of several linear instabilities and one nonlinear parametric instability in this connection. Two of the linear instabilities are qualitatively different f…
The nonequilibrium dynamics of vortices in 2D quantum fluids can be predicted by accounting for the way in which vortex ellipticity is coupled to the gradient in background fluid density. In the absence of nonlinear interactions, a harmonically trapped fluid can be analyzed analytically to show that single vortices will move in an elliptic trajectory that has the same orientation and aspect ratio as the vortex projection itself. This allows the vortex ellipticity to be estimated through observation of its trajectory. A combination of analysis and numerical simulation is then used to show that …
Three-dimensional numerical simulation of long-lived quantum vortex knots and links in a trapped Bose-Einstein condensate
本文用三维Gross-Pitaevskii方程数值模拟了零温下各向异性简谐势阱中原子玻色-爱因斯坦凝聚体中最简单的环面型涡旋结、解结和链的动力学。这种准定常旋转涡结构的寿命已被发现相当长的系统在广泛的参数域。这一结果与先前基于近似描述涡丝动力学的简化一维模型的预测定性一致[V. P. Ruban，JETP 126，397（2018）]。
Perturbative behaviour of a vortex in a trapped Bose-Einstein condensate
我们导出了一组描述玻色-爱因斯坦凝聚体中单个扰动涡线的形状和行为的方程。通过使用一个匹配的渐近展开和一个独特的坐标变换的关系，一个漩涡的速度，任何地方沿线，被发现在该位置的捕获，旋转和扭曲的线。这个关系然后被用来找到一组微分方程，给出线的特定形状和运动。这项工作纠正了阿纳托利A. Svidzinsky和Alexander L. Fetter [Phys. Rev. A \textbf{62}，063617（2000）]，并能够与最近的数值结果进行比较。
Diversified vortex phase diagram for a rotating trapped two-band Fermi gas in the BCS-BEC crossover
我们使用最近开发的有限温度有效场论[Phys. Rev. A $\bf{94}$，023620（2016）]，报告了限制在圆柱对称抛物型捕获势中的旋转双带费米气体的平衡涡旋相图。一个非单调的共振依赖的自由能作为温度和旋转频率的函数揭示了一个双带超流体。我们特别关注的新功能，出现的结果带间相互作用，可以通过实验解决。自由能的共振依赖性直接表现在涡旋相图中，其中整数和分数涡旋状态的稳定区域被发现。该研究包括BCS-BEC交叉制度和低于临界温度$T_{c}$的整个温度范围。在BCS和BEC制度中，涡旋物质作为带间耦合的函数的行为明显不同。
We explore the effect of using two-dimensional matter-wave vortices to confine an ensemble of bosonic quantum impurities. This is modelled theoretically using a mass-imbalanced homogeneous two component Gross-Pitaevskii equation where each component has independent atom numbers and equal atomic masses. By changing the mass imbalance of our system we find the shape of the vortices are deformed even at modest imbalances, leading to barrel shaped vortices; which we quantify using a multi-component variational approach. The energy of impurity carrying vortex pairs are computed, revealing a mass-de…
Phases of a rotating Bose-Einstein condensate trapped in a hard-wall potential
Université Sorbonne Paris Nord（巴黎索邦大学）；CNRS（法国国家科学研究中心）；Hellenic Mediterranean University（希腊地中海大学）；HMU Research Center, Institute of Emerging Technologies（HMU新兴技术研究所）
We study the dynamics of phase defects trapped in a finite optically imprinted ring lattice in binary polariton condensates, under the influence of the cross-interaction (CI) between the condensates in different spin components and the spin-orbit interaction (SOI). In this configuration, we find that a vortex circulates unidirectionally in optically induced orbits because of the Magnus force acting in the polariton fluid, and the vortex' angular velocity is influenced by the SOI and CI. Interestingly, in our system, these two interactions can also lead to elongated and frozen phase defects, fo…
We theoretically examine the vortex states of a gas of trapped quasi-two-dimensional ultracold bosons subject to a density-dependent gauge potential, realizing an effective nonlinear rotation of the atomic condensate, which we also show is within the reach of current experimental techniques with ultracold atom experiments. The nonlinear rotation has a two-fold effect; as well as distorting the shape of the condensate it also leads to an inhomogeneous vorticity resulting in novel morphological and topological states, including ring vortex arrangements that do not follow the standard Abrikosov r…
The threshold conditions for a rotating pancake-like asymmetric quartic-quadratic confined condensate to break in two localized fragments, as well as to produce giant vortex at the center within the vortex-pattern distributions, are investigated within the Thomas-Fermi (TF) approximation and exact numerical solution of the corresponding Gross-Pitaevskii (GP) formalism. By comparing the TF predictions with exact GP solutions, in our investigation with two different quartic-quadratic trap geometries, of particular relevance is to observe that the TF approach is not only very useful to display th…
