Abstract
Non-Hermitian physics in open systems has garnered significant attention for its exotic phenomena, particularly surrounding exceptional points that offer transformative potential for multifunctional devices. Central to this field are parity-time (\({{\mathcal{P}}}{{\mathcal{T}}}\)) symmetry-defined by balanced gain and loss-and its counterpart, anti-\({{\mathcal{P}}}{{\mathcal{T}}}\) symmetry. However, integrating these divergent concepts into a unified acoustic platform remains an unattainable challenge. In this study, we employ laser-induced thermoacoustics (LIT) to integrate a tunable amplifying component into a non-Hermitian system. By exciting an ultrathin carbon nanotube (CNT) film through laser irradiation, we experimentally observe the phase transitions between \({{\mathcal{P}}}{{\mathcal{T}}}\) and anti-\({{\mathcal{P}}}{{\mathcal{T}}}\) symmetries. Furthermore, our findings demonstrate the creation of selectable scattering states and the generation of acoustic vortex beams (VBs), facilitating both \({{\mathcal{P}}}{{\mathcal{T}}}\)-symmetric scattering and the conversion of topological charges. This acoustically transparent strategy bypasses traditional, path-blocking compensation schemes, offering a versatile framework for controlled non-Hermitian phase transitions in next-generation integrated devices.
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Acknowledgements
This work was supported by the National Key R&D Program of China (2022YFA1404400), the National Natural Science Foundation of China (12474448, 12225408, 12074183, 11904035, and 12227809), the China Postdoctoral Science Foundation (2024M751371), the Natural Science Foundation of Jiangsu Province (BK20241774), the Qing Lan Project of Jiangsu Province, Young Elite Scientists Sponsorship Program by Jiangsu Province (JSTJ-2024-143) and the Natural Science Foundation of the Jiangsu Higher Education Institutions of China (23KJD140001). R.P. acknowledges support from the National Key R&D Program of China (2022YFA1404303), the National Natural Science Foundation of China (12234010), and the Natural Science Foundation of Jiangsu Province (BK20233001). J.C. acknowledges support from the Spanish Ministry of Science and Innovation through a Consolidación Investigadora grant (CNS2022-135706).
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H.Z. and Y.C. conceived the idea and initiated the project. Y.C., R.P., X.L., and J.C. guided the research. H.Z., R.F,. and W.X. carried out the theoretical analyses and conducted FEM simulations. H.Z., R.F., W.X., K.S., A.Z., Z.Z., C.S., C.M., and Y.B. designed the experimental setup and conducted the measurements. H.Z., Y.C., and J.C. wrote the manuscript. All authors contributed to the discussions of the results and the manuscript preparation. H.Z. and R.F. contributed equally to this work.
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Zhang, H., Fan, R., Xiong, W. et al. Experimental observation of non-Hermitian phase transitions using laser-induced thermoacoustics. Nat Commun (2026). https://doi.org/10.1038/s41467-026-69986-w
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DOI: https://doi.org/10.1038/s41467-026-69986-w
