If a quantum fluid is driven with enough angular momentum, at equilibrium the ground state of the system is given by a lattice of quantized vortices whose density is prescribed by the quantization of circulation. We report on the first experimental study of the Feynman-Onsager relation in a nonequilibrium polariton fluid, free to expand and rotate. Upon initially imprinting a lattice of vortices in the quantum fluid, we track the vortex core positions on picosecond timescales. We observe an accelerated stretching of the lattice and an outward bending of the linear trajectories of the vortices, due to the repulsive polariton interactions. Access to the full density and phase fields allows us to detect a small deviation from the Feynman-Onsager rule in terms of a transverse velocity component, due to the density gradient of the fluid envelope acting on the vortex lattice.

中文翻译：

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膨胀的极化子量子流体中涡旋晶格的动力学

如果以足够的角动量驱动量子流体，则在平衡时，系统的基态由量子化涡旋的晶格给出，其密度由循环的量子化规定。我们报告了在自由膨胀和旋转的非平衡极化流体中 Feynman-Onsager 关系的第一次实验研究。在最初在量子流体中刻印涡旋晶格后，我们在皮秒时间尺度上跟踪涡旋核心位置。由于排斥性极化子相互作用，我们观察到晶格的加速拉伸和涡旋的线性轨迹的向外弯曲。访问全密度和相位场使我们能够在横向速度分量方面检测到与 Feynman-Onsager 规则的小偏差，