Department of Physics, University of California at Berkeley, CA, USA.
Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil.
Sci Rep. 2017 Jan 16;7:40122. doi: 10.1038/srep40122.
Vortices are essential to angular momentum in quantum systems such as ultracold atomic gases. The existence of quantized vorticity in bosonic systems stimulated the development of the Gross-Pitaevskii mean-field approximation. However, the true dynamics of angular momentum in finite, interacting many-body systems like trapped Bose-Einstein condensates is enriched by the emergence of quantum correlations whose description demands more elaborate methods. Herein we theoretically investigate the full many-body dynamics of the acquisition of angular momentum by a gas of ultracold bosons in two dimensions using a standard rotation procedure. We demonstrate the existence of a novel mode of quantized vorticity, which we term the phantom vortex. Contrary to the conventional mean-field vortex, can be detected as a topological defect of spatial coherence, but not of the density. We describe previously unknown many-body mechanisms of vortex nucleation and show that angular momentum is hidden in phantom vortices modes which so far seem to have evaded experimental detection. This phenomenon is likely important in the formation of the Abrikosov lattice and the onset of turbulence in superfluids.
涡旋对于超冷原子气体等量子系统中的角动量至关重要。玻色子系统中量子涡旋的存在激发了 Gross-Pitaevskii 平均场近似的发展。然而，像囚禁玻色-爱因斯坦凝聚体这样的有限相互作用多体系统中的角动量的真实动力学通过出现量子相关而变得更加丰富，而对其的描述需要更精细的方法。在此，我们使用标准的旋转程序从理论上研究了二维中超冷玻色气体获得角动量的全多体动力学。我们证明了存在一种新型的量子涡旋模式，我们称之为幻影涡旋。与传统的平均场涡旋不同，它可以作为空间相干性的拓扑缺陷而被检测到，而不是密度的。我们描述了以前未知的涡旋成核的多体机制，并表明角动量隐藏在幻影涡旋模式中，这些模式迄今为止似乎逃避了实验检测。这种现象在超流的阿布里科索夫晶格形成和湍流开始中可能很重要。
