论文标题
球形超级量子液滴的集体激发
Collective excitations of a spherical ultradilute quantum droplet
论文作者
论文摘要
在三个维度中，可以在自由空间中实现异国情调的新型超量子量液滴，当平均场吸引力（即带有平均场能$ e _ {\ textrm {\ textrm {mf}} \ propto-propto-n^{2} $的均值$ n $ n $ n $ n of the partecation i。 $ e _ {\ textrm {bmf}}} \ propto n^{2+γ} $）。如果我们考虑Lee-huang-yang（Lhy）能量功能，则参数$γ> 0 $通常会采用$ 1/2 $的值，但是当超过效应变得重要或三体相互作用时，它可能会有所不同。在这里，我们从理论上研究了三维量子液滴的集体激发受到参数$γ$的影响和弱谐波捕获势，这两者都可以在实验中调整。我们使用基于高斯变量ANSATZ的近似方法，以及由线性化的扩展Gross-Pitaevskii方程式产生的Bogoliubov方程的确切数值解。 We show that one of the key features of quantum droplets, i.e., the existence of the surface modes with dispersion relation $ω_{s}\propto k^{3/2}$ is very robust with respect to the changes either in the parameter $γ$ or in the harmonic trapping potential.我们预测在典型的实验条件下，二进制$^{39} $ k混合物实现的液滴的激发光谱，这可能很容易在当前的冷原子实验室中进行测量。
In three dimensions, exotic new state of matter of self-bound ultradilute quantum droplets can be realized in free space, when the mean-field attraction (i.e., with mean-field energy $E_{\textrm{MF}}\propto-n^{2}$ at the density $n$) is balanced by the repulsive beyond-mean-field quantum fluctuations (i.e., $E_{\textrm{BMF}}\propto n^{2+γ}$). The parameter $γ>0$ typically takes the value $1/2$ if we consider the Lee-Huang-Yang (LHY) energy functional, but it can vary when the beyond-LHY-effect becomes important or the three-body interaction becomes dominant. Here, we theoretically investigate how collective excitations of a three-dimensional quantum droplet are affected by the parameter $γ$ and a weak harmonic trapping potential, both of which could be tuned in experiments. We use both the approximate approach based on a Gaussian variational ansatz and the exact numerical solution of the Bogoliubov equations resulting from the linearized time-dependent extended Gross-Pitaevskii equation. We show that one of the key features of quantum droplets, i.e., the existence of the surface modes with dispersion relation $ω_{s}\propto k^{3/2}$ is very robust with respect to the changes either in the parameter $γ$ or in the harmonic trapping potential. We predict the excitation spectrum of the droplet realized by binary $^{39}$K mixtures under the typical experimental conditions, which might be readily measured in current cold-atom laboratories.
