We use an atomic fountain clock to measure quantum scattering phase shifts precisely through a series of narrow, low-field Feshbach resonances at average collision energies below $1\mu \mathrm{K}$. Our low spread in collision energy yields phase variations of order $\pm \pi /2$ for target atoms in several $F$, $m_F$ states. We compare them to a theoretical model and establish the accuracy of the measurements and the theoretical uncertainties from the fitted potential. We find overall excellent agreement, with small statistically significant differences that remain unexplained.

中文翻译：

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超低场处跨越Feshbach共振的量子散射相移的原子钟测量

我们使用原子喷泉时钟通过一系列窄的，低场的Feshbach共振精确测量量子散射相移，平均共振能量低于 $\mathrm{1个}\mu \mathrm{ķ}$。我们碰撞能量的低扩散会产生阶次的相位变化$\pm \pi /\mathrm{2个}$ 对于几个目标原子 $F$， ${米}_F$状态。我们将它们与理论模型进行比较，并根据拟合电位确定测量的准确性和理论不确定性。我们发现总体上的一致性很好，但统计上的细微差异仍然无法解释。