Iadecola Thomas, Žnidarič Marko
Joint Quantum Institute and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
Physics Department, Faculty of Mathematics and Physics, University of Ljubljana, 1000 Ljubljana, Slovenia.
Phys Rev Lett. 2019 Jul 19;123(3):036403. doi: 10.1103/PhysRevLett.123.036403.
We demonstrate the existence of exact atypical many-body eigenstates in a class of disordered, interacting one-dimensional quantum systems that includes the Fermi-Hubbard model as a special case. These atypical eigenstates, which generically have finite energy density and are exponentially many in number, are populated by noninteracting excitations. They can exhibit Anderson localization with area-law eigenstate entanglement or, surprisingly, ballistic transport at any disorder strength. These properties differ strikingly from those of typical eigenstates nearby in energy, which we show give rise to diffusive transport as expected in a chaotic quantum system. We discuss how to observe these atypical eigenstates in cold-atom experiments realizing the Fermi-Hubbard model, and comment on the robustness of their properties.
我们证明了在一类无序的、相互作用的一维量子系统中存在精确的非典型多体本征态，费米-哈伯德模型作为特殊情况包含在该类系统中。这些非典型本征态通常具有有限的能量密度且数量呈指数级，由非相互作用激发填充。它们可以表现出具有面积律本征态纠缠的安德森局域化，或者令人惊讶的是，在任何无序强度下都能实现弹道输运。这些性质与附近能量的典型本征态的性质显著不同，我们表明典型本征态会导致如混沌量子系统中预期的扩散输运。我们讨论了如何在实现费米-哈伯德模型的冷原子实验中观测这些非典型本征态，并对其性质的稳健性进行了评论。
