Observation of topological surface phonons in diamond with nonlinear optics
Abstract
Topological quantum states in electronic systems have profoundly transformed the understanding of phases of matter. Recent theories predict novel vibrational topological quantum states, i.e., topological phonons in various solids. However, this paradigm is yet to be established due to the lack of convincing experimental verification of topological surface phonons---a hallmark signature of topological phonon states. Here, we report the discovery of topological surface phonons in diamond using sum-frequency spectroscopy---a nonlinear optical spectroscopy capable of probing surface phonons with high sensitivity. Diamond, known for exceptional hardness and thermal transport, is unveiled as a phonon topological semimetal hosting topological nodal-lines and nexus triple points in the bulk. With consistent theory and experiments, we uncover the resultant topological surface phonons on diamond (111) and (100) surfaces. Moreover, by chemically modifying these surfaces, we reveal the disorder effect on topological surface phonons. These findings pave the way for bridging two fundamental domains: quantum topology and lattice dynamics, besides having important implications on diamond-based devices and functional interfaces.
Related
- Direct observation of a spin-polarized surface Dirac gap in the antiferromagnetic topological insulator NdBi
- Optical activation of nonlinear Hall effect in topological insulators with warped Fermi surface
- Chiral Surface Phonons
- Topological edge and domain-wall phonons in the mass-dimerized diatomic chain: complex band structure, Zak phase, and spectral unfolding
- Correlation Imaging via Hybrid Entanglement between Microwave Photons and Surface Acoustic Wave Phonons
BibTeX
@misc{wang2026observation,
title = {{Observation of topological surface phonons in diamond with nonlinear optics}},
author = {Qi Wang and Xinyi Liu and Xinyue Sheng and Zhi-Kang Lin and Xiaowei Lu and Xiaosheng Yang and Peining Li and Yizhou Liu and Chang-Hui Li and Wei-Tao Liu and Jian-Hua Jiang},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.12362},
eprint = {2609.12362},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.12362},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Observation of topological surface phonons in diamond with nonlinear optics
AU - Qi Wang
AU - Xinyi Liu
AU - Xinyue Sheng
AU - Zhi-Kang Lin
AU - Xiaowei Lu
AU - Xiaosheng Yang
AU - Peining Li
AU - Yizhou Liu
AU - Chang-Hui Li
AU - Wei-Tao Liu
AU - Jian-Hua Jiang
PY - 2026
DA - 2026/09/11
PB - arXiv
DO - 10.48550/arxiv.2609.12362
UR - https://arxiv.org/abs/2609.12362
AB - Topological quantum states in electronic systems have profoundly transformed the understanding of phases of matter. Recent theories predict novel vibrational topological quantum states, i.e., topological phonons in various solids. However, this paradigm is yet to be established due to the lack of convincing experimental verification of topological surface phonons---a hallmark signature of topological phonon states. Here, we report the discovery of topological surface phonons in diamond using sum-frequency spectroscopy---a nonlinear optical spectroscopy capable of probing surface phonons with high sensitivity. Diamond, known for exceptional hardness and thermal transport, is unveiled as a phonon topological semimetal hosting topological nodal-lines and nexus triple points in the bulk. With consistent theory and experiments, we uncover the resultant topological surface phonons on diamond (111) and (100) surfaces. Moreover, by chemically modifying these surfaces, we reveal the disorder effect on topological surface phonons. These findings pave the way for bridging two fundamental domains: quantum topology and lattice dynamics, besides having important implications on diamond-based devices and functional interfaces.
ER -