We report an observation of a dynamical super Efimovian expansion in a strongly interacting Fermi gas by engineering time dependent external harmonic trap frequencies. When the trap frequency is tailored as $[1/4t^2+1/t^2\lambda {\log }^2(t/t_{*}){]}^{1/2}$, where $t_{*}$ and $\lambda$ are two controllable parameters, and the change is faster than a critical value, the expansion of such a quantum gas shows novel dynamics that share the same characteristics as the super Efimov effect. A clear double-log periodicity with discrete geometric scaling emerges for the cloud size in the expansion. The universality of such scaling dynamics is verified both in the noninteracting and in the unitarity limit of Fermi gas. Moreover, the measured energy scaling reveals that the potential and internal energy also show double-log periodicity with a $\pi /2$ phase difference, but the total energy is monotonically decreased. Observing super Efimovian evolution represents a paradigm in probing universal properties and allows us in a new way to study many-body nonequilibrium dynamics with experiments.

中文翻译：

---

单一费米气体中动力超埃夫莫夫扩张的观测

我们通过工程时间相关的外部谐波陷波频率报告了在强相互作用费米气体中的动态超埃菲莫夫膨胀的观察结果。将陷波频率调整为$[\mathrm{1个}/4{Ť}^{\mathrm{2个}}+\mathrm{1个}/{Ť}^{\mathrm{2个}}\lambda {\mathrm{日志}}^{\mathrm{2个}}（Ť/{Ť}_{*}）{]}^{\mathrm{1个}/\mathrm{2个}}$， 在哪里 ${Ť}_{*}$ 和 $\lambda$是两个可控制的参数，并且变化快于临界值，这种量子气体的膨胀显示出新颖的动力学，这些动力学具有与超级Efimov效应相同的特性。对于扩展中的云大小，出现了具有离散几何比例缩放的清晰的双对数周期性。这样的定标动力学的普遍性在费米气体的非相互作用和统一极限中都得到了验证。此外，测得的能量标度表明，势能和内部能量也显示出双对数周期性，其中$\pi /\mathrm{2个}$相位差，但总能量单调降低。观察超级Efimovian演化代表了探索普遍性质的范例，并允许我们以一种新的方式通过实验研究多体非平衡动力学。