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arXiv 0909.1683cond-mat.quant-gas
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有限温度玻色-爱因斯坦凝聚体中涡旋停滞的非平衡动力学

Nonequilibrium dynamics of vortex arrest in a finite-temperature Bose-Einstein condensate

T. M. Wright, A. S. Bradley, R. J. Ballagh

摘要:

我们使用哈密顿经典场方法,对旋转的玻色-爱因斯坦凝聚体被固定的陷阱各向异性捕获进行了有限温度动力学模拟。我们考虑一个准二维凝聚包含一个单一的涡旋平衡与旋转热云。引入一个椭圆形变形的捕获势导致系统的角动量损失。我们识别了凝聚和非平衡场的互补热分量,并比较了它们的角动量和角速度的演化。通过改变陷阱的各向异性,我们改变的涡云和云陷阱耦合的相对效率。对于强的陷阱各向异性的热云的角动量可能完全耗尽之前的涡旋开始衰减。对于弱的陷阱各向异性,热云表现出一个长寿命的稳定状态,它在中间角速度旋转。

英文摘要:

We perform finite-temperature dynamical simulations of the arrest of a rotating Bose-Einstein condensate by a fixed trap anisotropy, using a Hamiltonian classical-field method. We consider a quasi-two-dimensional condensate containing a single vortex in equilibrium with a rotating thermal cloud. Introducing an elliptical deformation of the trapping potential leads to the loss of angular momentum from the system. We identify the condensate and the complementary thermal component of the nonequilibrium field, and compare the evolution of their angular momenta and angular velocities. By varying the trap anisotropy we alter the relative efficiencies of the vortex-cloud and cloud-trap coupling. For strong trap anisotropies the angular momentum of the thermal cloud may be entirely depleted before the vortex begins to decay. For weak trap anisotropies, the thermal cloud exhibits a long-lived steady state in which it rotates at an intermediate angular velocity.

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