论文标题
各向异性介导的恢复定位
Anisotropy-mediated reentrant localization
论文作者
论文摘要
我们考虑一个2D偶极系统,$ d = 2 $,具有广义的偶极 - 偶极相互作用$ \ sim r^{ - a} $,以及通过与腔模式的交互,在陷阱离子或rydberg-atom系统中进行实验中的功率$ a $ A $。当可以有效地将问题视为单粒子的相互作用提供远距离偶极样跳跃时,我们将重点放在稀释的偶极激发案例上。我们表明,产生各向异性偶极交换的偶极子的空间均匀倾斜$β$导致非平整的重新进入定位以外的定位器膨胀,$ a <d $,与随机偶极偶导向的模型不同。发现安德森过渡是以倾斜参数的有限值进行的,$β= a $,$ 0 <a <d $,$β= a/(a-d/2)$,$ d/2 <a <d $,显示了小小的各向异性值的稳健性。广泛的数值计算和分析方法都显示了大部分光谱中的幂律局部特征状态,最近发现了二元性$ a \ leftrightArrow 2d-a $的空间衰减率,在过渡的本地化侧,$ a> a__ {at} $。由于在两种光谱边缘存在千古的延伸状态,因此出现了这种定位,这构成热力学极限中的零部分状态,但由于系统大小而衰减,尽管衰变非常缓慢。
We consider a 2d dipolar system, $d=2$, with the generalized dipole-dipole interaction $\sim r^{-a}$, and the power $a$ controlled experimentally in trapped-ion or Rydberg-atom systems via their interaction with cavity modes. We focus on the dilute dipolar excitation case when the problem can be effectively considered as single-particle with the interaction providing long-range dipolar-like hopping. We show that the spatially homogeneous tilt $β$ of the dipoles giving rise to the anisotropic dipole exchange leads to the non-trivial reentrant localization beyond the locator expansion, $a<d$, unlike the models with random dipole orientation. The Anderson transitions are found to occur at the finite values of the tilt parameter $β= a$, $0<a<d$, and $β= a/(a-d/2)$, $d/2<a<d$, showing the robustness of the localization at small and large anisotropy values. Both extensive numerical calculations and analytical methods show power-law localized eigenstates in the bulk of the spectrum, obeying recently discovered duality $a\leftrightarrow 2d-a$ of their spatial decay rate, on the localized side of the transition, $a>a_{AT}$. This localization emerges due to the presence of the ergodic extended states at either spectral edge, which constitute a zero fraction of states in the thermodynamic limit, decaying though extremely slowly with the system size.