Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session D44: Flatbands: Finetuning and InteractionsInvited Live Streamed
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Sponsoring Units: DCMP DCOMP Chair: Raymond Orbach, University of Texas at Austin Room: McCormick Place W-375C |
Monday, March 14, 2022 3:00PM - 3:36PM |
D44.00001: Many-body flatband localization Invited Speaker: Sergej Flach We generate translationally invariant systems exhibiting many-body localization from all-bands-flat single-particle lattice Hamiltonians dressed with suitable short-range many-body interactions. This many-body flatband localization is based on symmetries of both single-particle and interaction terms in the Hamiltonian, and it holds for any interaction strength. We propose a generator of corresponding Hamiltonians which covers both interacting bosons and fermions for arbitrary lattice dimensions, and we provide explicit examples of such models in one and two lattice dimensions. We also explicitly construct an extensive set of local integrals of motion for this set of models. |
Monday, March 14, 2022 3:36PM - 4:12PM |
D44.00002: Finetuning localization in interacting flatband networks Invited Speaker: Carlo Danieli Linear wave equations on translationally invariant flatband networks exhibit one or more dispersionless bands in their Bloch spectrum, and host compact localized eigenstates (CLS) with nonzero amplitudes restricted to a finite volume. While yielding remarkable single particle localization features, CLSs are typically highly sensitive to perturbations (e.g. disorder, external fields, interaction). However, the impact of such perturbations strongly depend on the chosen flatband network. In this talk, we focus on the case of interacting flatband networks, and overview finetuning protocols involving the interaction terms (both classical and quantum) and the network geometry which yield diverse localization features. We show how these finetuning protocols result in spatially compact time periodic breather solutions in the classical nonlinear case, and in the emergence of an extensive number of local integrals of motions in the quantum case, yielding signatures of disorder-free many-body localization. We also discuss the case of lattices lacking dispersion (i.e. all bands are flat) where finetuning leads to the complete suppression of transport. |
Monday, March 14, 2022 4:12PM - 4:48PM |
D44.00003: Many-body chaos and topological order in flat-band optical lattices Invited Speaker: Tigran A Sedrakyan Optical lattices are remarkable for their capacity to host rich physics. In this talk, I will discuss the flat-band optical lattices from the perspective of the potential realization of novel states of quantum matter, including the quantum chaotic Sachdev-Ye-Kitaev system and spin-liquids. |
Monday, March 14, 2022 4:48PM - 5:24PM Withdrawn |
D44.00004: Flatband photonic lattices: from light localization to topological physics Invited Speaker: Zhigang Chen Flat-band systems have attracted considerable interest in many different branches of physics in the past decade, providing a flexible platform for studying a variety of fundamental phenomena. Engineered flat-band structures have now been realized in different material systems, and in particular, in the realm of photonics. In this talk, I will report our recent work on flat-band localization and associated topological phenomena in photonic lattices, including momentum-to-real-space mapping of topological singularities, unconventional localized flatband states arising from real-space topology, higher-order topological states in Dirac-like photonic structures. Our results from flat-band photonic lattices may provide inspiration for exploring fundamentals and applications of flat-band physics in other materials or complex systems beyond photonics. |
Monday, March 14, 2022 5:24PM - 6:00PM |
D44.00005: Orbital Chern Insulator and Spontaneous Time Reversal Symmetry Breaking of Electron Systems with Partially Filled Energy Bands Invited Speaker: Donna Sheng In this talk, I will present numerical evidendence of an interaction-driven spontaneous quantum Hall effect emerging in extended fermion-Hubbard models based on state-of-the-art density-matrix renormalization group simulations. For electrons on kagome lattice with half-filled lowest flat bands by considering the antiferromagnetic Heisenberg interaction (J) and short-range Coulomb interactions (V), I will discuss a quantum phase diagram and identify a fully spin-polarized phase. I will show that neighboring repulsions (V) drive a spontaneous chiral current, which makes the system an orbital Chern insulator characterized by a quantized Hall conductance. We further show that the orbital Chern insulator is robust against small antiferromagnetic coupling (J) while a nonmagnetic phase with spin and charge nematicity appears at larger J. At last, we will also demonstrate the effect of electron doping on frustrated systems to unveil the connection between spontaneous time reversal symmetry breaking and topological superconductivity. |
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