论文标题
中央Qudit问题中的多体流动性边缘
Inverted many-body mobility edge in a central qudit problem
论文作者
论文摘要
许多有趣的实验系统，例如腔QED或中央自旋模型，涉及到单个谐波模式的全局耦合。不平衡的情况下，在哪些条件下，在这种全球耦合中存活的局部阶段仍不清楚。我们研究了在无序的Ising模型中的能量依赖性定位，该模型具有横向和纵向场与$ d $级别系统（QUDIT）耦合。引人注目的是，我们发现了一个倒置的迁移率边缘，高能状态是局部定位的，而低能状态则被定位。我们的结果得到了换档本特征态定位和Krylov时间演变的支持，分别为$ L = 13 $和$ 18 $。我们主张定位相变的临界能量，该定位相变为$ e_c \ propto l^{1/2} $，与有限大小的数字一致。我们还向较低的能量中的重进入MBL相显示了证据，尽管该制度中心模式的强大影响。大型$ s $和某些腔Qed型号的中央旋转$ S $问题应发生类似的结果。
Many interesting experimental systems, such as cavity QED or central spin models, involve global coupling to a single harmonic mode. Out-of-equilibrium, it remains unclear under what conditions localized phases survive such global coupling. We study energy-dependent localization in the disordered Ising model with transverse and longitudinal fields coupled globally to a $d$-level system (qudit). Strikingly, we discover an inverted mobility edge, where high energy states are localized while low energy states are delocalized. Our results are supported by shift-and-invert eigenstate targeting and Krylov time evolution up to $L=13$ and $18$ respectively. We argue for a critical energy of the localization phase transition which scales as $E_c \propto L^{1/2}$, consistent with finite size numerics. We also show evidence for a reentrant MBL phase at even lower energies despite the presence of strong effects of the central mode in this regime. Similar results should occur in the central spin-$S$ problem at large $S$ and in certain models of cavity QED.
