Atoms trapped in the evanescent field around a nanofiber experience strong coupling to the light guided in the fiber mode. However, due to the intrinsically strong positional dependence of the coupling, thermal motion of the ensemble limits the use of nanofiber trapped atoms for some quantum tasks. We investigate the thermal dynamics of such an ensemble using short light pulses to make a spatially inhomogeneous population transfer between atomic states. As we monitor the wave packet of atoms created by this scheme, we find a damped oscillatory behavior which we attribute to sloshing and dispersion of the atoms. Oscillation frequencies range around $$100\hbox { kHz}$$ 100 kHz , and motional dephasing between atoms happens on a timescale of $$10\,\upmu \hbox {s}$$ 10 μ s . Comparison to Monte Carlo simulations of an ensemble of 1000 classical particles yields reasonable agreement for simulated ensemble temperatures between $$25$$ 25 and $${40}\,\upmu \hbox {K}$$ 40 μ K .

中文翻译：

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纳米级光学俘获电位中原子运动的测量和模拟

被困在纳米纤维周围的渐逝场中的原子与以光纤模式引导的光强耦合。然而，由于耦合固有的强位置依赖性，系综的热运动限制了纳米纤维捕获原子在某些量子任务中的使用。我们使用短光脉冲在原子状态之间进行空间不均匀的种群转移来研究这种集合的热动力学。当我们监测由该方案产生的原子波包时，我们发现了阻尼振荡行为，我们将其归因于原子的晃动和分散。振荡频率范围约为 $$100\hbox { kHz}$$ 100 kHz ，原子之间的运动移相发生在 $$10\,\upmu \hbox {s}$$ 10 μ s 的时间尺度上。