Fate of chiral order and impurity self-pinning in flat bands with local symmetry
arXiv:2410.01780 · doi:10.1103/PhysRevB.111.064514
Abstract
Interacting bosons on a single plaquette threaded by a -flux can spontaneously break time-reversal symmetry, resulting in a chiral loop current. Connecting such bosonic -flux plaquettes in a dispersive configuration was recently shown to lead to long-range chiral order. Here, instead, we design a chain of -flux plaquettes that exhibits an all-flat-bands single-particle energy spectrum and an extensive set of local symmetries. Using Elitzur's theorem, we show that these local symmetries prevent the emergence of long-range chiral order. Moreover, projecting the dynamics to a Creutz ladder model with an effective intra-rung interaction allows one to derive simple spin Hamiltonians capturing the ground state degeneracy and the low-energy excitations, and to confirm the absence of chiral order. Nevertheless, we show how to obtain gauge-invariant information from a mean-field approach, which explicitly break gauge-invaraince. Finally, we observe an ``impurity self-pinning'' phenomenon, when an extra boson is added on top of a ground state at integer filling, resulting in a non-dispersive density peak. Exact diagonalization benchmarks are also provided, and experimental perspectives are discussed.
14 pages, 10 figures
References in corpus (19)
- Signatures of Fractional Quantum Anomalous Hall States in Twisted MoTe2 Bilayer
- Observation of Fractionally Quantized Anomalous Hall Effect
- Quantum anomalous Hall effect from intertwined moiré bands
- Integer and fractional Chern insulators in twisted bilayer MoTe2
- Quantum Many-Body Scars and Hilbert Space Fragmentation: A Review of Exact Results
- QuSpin: a Python Package for Dynamics and Exact Diagonalisation of Quantum Many Body Systems part I: spin chains
- Superfluidity and Quantum Geometry in Twisted Multilayer Systems
- Orbital superfluidity in the -band of a bipartite optical square lattice
- Bose condensation in flat bands
- Many-body localization dynamics from gauge invariance
- Eta-Pairing in Hubbard Models: From Spectrum Generating Algebras to Quantum Many-Body Scars
- Many-Body Flatband Localization
- Aharonov-Bohm Caging and Inverse Anderson transition in Ultracold Atoms
- Quantum Caging in Interacting Many-Body All-Bands-Flat Lattices
- Enhancing disorder-free localization through dynamically emergent local symmetries
- Flat-band localization and interaction-induced delocalization of photons
- Compactly Supported Wannier Functions and Strictly Local Projectors
- Deconfinement Dynamics of Fractons in Tilted Bose-Hubbard Chains
- Chiral orbital order of interacting bosons without higher bands