Imaging an obstructed Wannier orbital
Abstract
In conventional insulators, electronic charge is localized in Wannier orbitals centered on the atoms. In an obstructed atomic insulator (OAI), the Wannier orbitals sit instead in the empty voids between atoms. These displaced orbitals give rise to an analog of the topological bulk-boundary correspondence, in which a boundary mode occurs only where the lattice termination severs an orbital. However, experimentally identifying OAIs has remained challenging, because the Wannier orbital of a dispersive electronic band is not an energy eigenstate and cannot be measured directly. Here we engineer an acoustic metamaterial hosting an isolated flat band, in which the Wannier orbitals become energy eigenstates. By measuring the amplitude and phase of the acoustic pressure field, we map the orbital's f-like structure and locate its Wannier center in a void between lattice sites---providing the first phase-resolved image of an obstructed Wannier orbital. By altering the lattice termination, we observe the predicted boundary states. Such acoustic flat-band metamaterials offer a direct probe of single-particle ingredients such as quantum geometry, which govern correlated phenomena in electronic flat bands, including proposed routes to unconventional superconductivity.
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BibTeX
@misc{huang2026imaging,
title = {{Imaging an obstructed Wannier orbital}},
author = {Yiting Huang and Benjamin H. November and Jonah Herzog-Arbeitman and Jiatong Yang and Jennifer E. Hoffman and Harris Pirie},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28738},
eprint = {2609.28738},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28738},
}
RIS
TY - UNPB
TI - Imaging an obstructed Wannier orbital
AU - Yiting Huang
AU - Benjamin H. November
AU - Jonah Herzog-Arbeitman
AU - Jiatong Yang
AU - Jennifer E. Hoffman
AU - Harris Pirie
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.28738
UR - https://arxiv.org/abs/2609.28738
AB - In conventional insulators, electronic charge is localized in Wannier orbitals centered on the atoms. In an obstructed atomic insulator (OAI), the Wannier orbitals sit instead in the empty voids between atoms. These displaced orbitals give rise to an analog of the topological bulk-boundary correspondence, in which a boundary mode occurs only where the lattice termination severs an orbital. However, experimentally identifying OAIs has remained challenging, because the Wannier orbital of a dispersive electronic band is not an energy eigenstate and cannot be measured directly. Here we engineer an acoustic metamaterial hosting an isolated flat band, in which the Wannier orbitals become energy eigenstates. By measuring the amplitude and phase of the acoustic pressure field, we map the orbital's f-like structure and locate its Wannier center in a void between lattice sites---providing the first phase-resolved image of an obstructed Wannier orbital. By altering the lattice termination, we observe the predicted boundary states. Such acoustic flat-band metamaterials offer a direct probe of single-particle ingredients such as quantum geometry, which govern correlated phenomena in electronic flat bands, including proposed routes to unconventional superconductivity.
ER -