Bose-Einstein condensates with a bent vortex in rotating traps
Bose-Einstein condensates with a bent vortex in rotating traps
复制标题
旋转陷阱中带有弯曲涡旋的玻色-爱因斯坦凝聚
DOI：
10.1140/epjd/e2003-00015-y
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
Y. Castin
中科院分区：
文献类型：
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作者：
M. Modugno;L. Pricoupenko;Y. Castin
翻译后摘要：我们认为一个3D稀释玻色-爱因斯坦凝聚在旋转谐波陷阱的热平衡。凝聚波函数是Gross-Pitaevskii能量泛函的局部最小值，我们用非常有效的共轭梯度法数值确定它。对于雪茄形谐波阱中的单涡构型，我们发现涡线是弯曲的，与Garcia-Ripoll和Perez-Garcia的数值预测一致[Phys.Rev.A63，041603（2001）]。我们推导出一个简单的能量泛函的涡线在雪茄形冷凝物，它允许物理上理解为什么涡线弯曲，并预测分析所需的最小旋转频率稳定弯曲涡线。这一分析预测与数值计算结果非常吻合。它还允许以简单的方式找到能量的鞍点，其中涡线在旋转坐标系中处于静止构型，但不是能量的局部最小值。最后，我们调查数值上的热波动的效果的涡线与直涡凝聚：我们可以预测发生了什么事，在一个单一的实现实验的Monte Carlo采样的原子场准分布函数的密度算子的气体在热平衡的Bogoliubov近似。
Abstract:We consider a 3D dilute Bose-Einstein condensate at thermal equilibrium in a rotating harmonic trap. The condensate wavefunction is a local minimum of the Gross-Pitaevskii energy functional and we determine it numerically with the very efficient conjugate gradient method. For single vortex configurations in a cigar-shaped harmonic trap we find that the vortex line is bent, in agreement with the numerical prediction of Garcia-Ripoll and Perez-Garcia [Phys. Rev. A 63, 041603 (2001)]. We derive a simple energy functional for the vortex line in a cigar-shaped condensate which allows to understand physically why the vortex line bends and to predict analytically the minimal rotation frequency required to stabilize the bent vortex line. This analytical prediction is in excellent agreement with the numerical results. It also allows to find in a simple way a saddle point of the energy, where the vortex line is in a stationary configuration in the rotating frame but not a local minimum of energy. Finally we investigate numerically the effect of thermal fluctuations on the vortex line for a condensate with a straight vortex: we can predict what happens in a single realization of the experiment by a Monte Carlo sampling of an atomic field quasi-distribution function of the density operator of the gas at thermal equilibrium in the Bogoliubov approximation.