Absence of two-body delocalization transitions in the two-dimensional Anderson-Hubbard model

Two-body mobility edge in the Anderson-Hubbard model in three dimensions: Molecular versus scattering states

Most of our quantitative understanding of disorder-induced metal-insulator transitions comes from numerical studies of simple noninteracting tight-binding models, like the Anderson model in three dimensions. An important outstanding problem is the fate of the Anderson transition in the presence of additional Hubbard interactions of strength $U$ between particles. Based on large-scale numerics, we compute the position of the mobility edge for a system of two identical bosons or two fermions with opposite spin components. The resulting phase diagram in the interaction-energy-disorder space posse…

Slow Dynamics in a Two-Dimensional Anderson-Hubbard Model

We study the real-time dynamics of a two-dimensional Anderson--Hubbard model using nonequilibrium self-consistent perturbation theory within the second-Born approximation. When compared with exact diagonalization performed on small clusters, we demonstrate that for strong disorder this technique approaches the exact result on all available timescales, while for intermediate disorder, in the vicinity of the many-body localization transition, it produces quantitatively accurate results up to nontrivial times. Our method allows for the treatment of system sizes inaccessible by any numerically exa…

Localization by bichromatic potentials versus Anderson localization

The one-dimensional propagation of waves in a bichromatic potential may be modeled by the Aubry-André Hamiltonian. The latter presents a delocalization-localization transition, which has been observed in recent experiments using ultracold atoms or light. It is shown here that, in contrast to Anderson localization, this transition has a classical origin, namely the localization mechanism is not due to a quantum suppression of a classically allowed transport process. Explicit comparisons with the Anderson model, as well as with experiments, are done.

Detecting delocalization-localization transitions from full density distributions

Characterizing the delocalization transition in closed quantum systems with a many-body localized phase is a key open question in the field of nonequilibrium physics. We exploit that localization of particles as realized in Anderson and standard many-body localization (MBL) implies Fock-space localization in single-particle basis sets characterized by a real-space index. Using a recently introduced quantitative measure for Fock-space localization computed from the density distributions, the occupation distance, we systematically study its scaling behavior across delocalozation transitions and …

Bose-Hubbard梯子上两个相互作用玻色子淬灭动力学中的通量增强局域化与重入退局域化

Flux enhanced localization and reentrant delocalization in the quench dynamics of two interacting bosons on a Bose-Hubbard ladder

本文研究双足Bose-Hubbard梯子上两个相互作用玻色子的淬灭动力学，发现均匀通量可增强束缚态局域化，并在通量与相互作用共同作用下表现出重入退局域化特征。

Disorder-induced Localization in a Strongly Correlated Atomic Hubbard Gas

We observe the emergence of a disorder-induced insulating state in a strongly interacting atomic Fermi gas trapped in an optical lattice. This closed quantum system free of a thermal reservoir realizes the disordered Fermi-Hubbard model, which is a minimal model for strongly correlated electronic solids. In measurements of disorder-induced localization obtained via mass transport, we detect interaction-driven delocalization and localization that persists as the temperature of the gas is raised. These behaviors are consistent with many-body localization, which is a novel paradigm for understand…

Anderson localization in an interacting fermionic system

In the present article, we discuss the role played by the interaction in the Anderson localization problem, for a system of interacting fermions in a one-dimensional disordered lattice, described by the Fermi Hubbard Hamiltonian, in presence of an on-site random potential. We show that, given the proper identification of the elementary excitations of the system described in terms of doublons and unpaired particles, the Anderson localization picture survives. Ensuing a "global quench", we show that the system exhibits a rich localization scenario, which can be ascribed to the nearly-free dynami…

Spin-mediated particle transport in the disordered Hubbard model

Motivated by the recent experiments that reported signatures of many-body localization of ultracold atoms in optical lattices [M. Schreiber {\it et al.}, Science {\bf 349}, 842 (2015)], we study dynamics of highly excited states in the strongly disordered Hubbard model in one dimension. Owing to the $SU(2)$ spin symmetry, spin degrees of freedom form a delocalized thermal bath with a narrow bandwidth. The spin bath mediates slow particle transport, eventually leading to delocalization of particles. The particle hopping rate is exponentially small in $t/W$ ($t$, $W$ being hopping and disorder s…

利用受击量子气体研究多体安德森金属-绝缘体转变

Many-Body Anderson Metal-Insulator Transition using Kicked Quantum Gases

该研究利用准周期受击超冷原子气体的动量空间晶格平台，实验探究多体效应对三维安德森金属-绝缘体转变的影响，观测到相互作用驱动的亚扩散及相边界处离域起始时间发散，且平均场模拟与实验定性吻合。

广义非厄米 SSH 模型中的局域化与拓扑转变

Localization and topological transitions in generalized non-Hermitian SSH models

该研究分析含复准周期与非互易跃迁的广义非厄米 SSH 模型，利用能量绕数和 Lyapunov 指数刻画不同边界条件下的退局域化转变，并揭示其与拓扑转变的关系。