Acoustic scattering singularities via quasi-Bound states in the continuum

Abstract

Non-Hermitian systems enable advanced control of wave propagation by exploiting engineered losses. This introduces an additional degree of freedom that permits the emergence of exceptional points (EPs). In this letter, we theoretically and experimentally demonstrate the control of scattering singularities in a non-Hermitian acoustic system using quasi-bound states in the continuum (qBICs). Through Friedrich-Wintgen interference, the losses of a two-port cavity are tuned until achieving critical coupling, yielding narrowband coherent perfect absorption with a quality factor of 140. Additionally, by coupling two distinct resonators, we observe the emergence of an EP, where both eigenvalues simultaneously coalesce and vanish, resulting in narrowband unidirectional absorption. Our results establish a connection between qBICs and scattering singularities and offer a route toward acoustic devices featuring narrowband resonances and tunable radiative losses.

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BibTeX RIS

BibTeX

@article{maddi2026acoustic,
  title = {{Acoustic scattering singularities via quasi-Bound states in the continuum}},
  author = {Anis Maddi and Mourad Oudich and Aurelien Merkel and Julio Martínez and Badreddine Assouar},
  journal = {Physical Review Applied},
  year = {2026},
  month = jun,
  doi = {10.1103/6bxx-pwbl},
  url = {https://hal.science/hal-05773042v1},
  note = {CC BY 4.0},
}

RIS

TY  - JOUR
TI  - Acoustic scattering singularities via quasi-Bound states in the continuum
AU  - Anis Maddi
AU  - Mourad Oudich
AU  - Aurelien Merkel
AU  - Julio Martínez
AU  - Badreddine Assouar
PY  - 2026
DA  - 2026/06/16
JO  - Physical Review Applied
DO  - 10.1103/6bxx-pwbl
UR  - https://hal.science/hal-05773042v1
AB  - Non-Hermitian systems enable advanced control of wave propagation by exploiting engineered losses. This introduces an additional degree of freedom that permits the emergence of exceptional points (EPs). In this letter, we theoretically and experimentally demonstrate the control of scattering singularities in a non-Hermitian acoustic system using quasi-bound states in the continuum (qBICs). Through Friedrich-Wintgen interference, the losses of a two-port cavity are tuned until achieving critical coupling, yielding narrowband coherent perfect absorption with a quality factor of 140. Additionally, by coupling two distinct resonators, we observe the emergence of an EP, where both eigenvalues simultaneously coalesce and vanish, resulting in narrowband unidirectional absorption. Our results establish a connection between qBICs and scattering singularities and offer a route toward acoustic devices featuring narrowband resonances and tunable radiative losses.
SN  - 2331-7019
ER  -

Abstract

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