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Coherent control of magnon–polaritons using an exceptional point

Nature Physics volume 21, pages 1570–1577 (2025)Cite this article

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A Publisher Correction to this article was published on 09 September 2025

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Abstract

In a non-Hermitian system, the amplitude of resonant oscillations can either grow or decay in time, corresponding to a mode with either gain or loss. When two coupled modes have a specific gain–loss imbalance, an exceptional point emerges at which both eigenfrequencies and eigenmodes of the system coalesce. Exceptional points have qualitative effects on the dynamics of systems due to their topological properties, and have been used to control systems including optical microcavities, the lasing of a parity–time-symmetric waveguide and terahertz pulse generation. A challenging open problem is the fully deterministic and direct manipulation of the systems’ loss and gain on timescales relevant to the coherent control of excitations. Here we demonstrate the rapid manipulation of the complex frequency of magnon–polaritons on durations much shorter than their decay rate, allowing us to exploit non-Hermitian physics for coherent control. By dynamically encircling an exceptional point, we demonstrate population transfer between coupled magnon–polariton modes. We then drive the system directly through an exceptional point, and demonstrate that this allows the coupled system to be prepared in an equal superposition of eigenmodes. These findings establish a highly controllable hybrid platform for exploring the rich dynamical properties of non-Hermitian systems.

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Fig. 1: Experimental configuration and strong coupling.
Fig. 2: Theoretical energy landscape for two non-Hermitian coupled resonators.
Fig. 3: Population transfer by encircling an EP.
Fig. 4: Equalizing state populations by traversing beyond and back through an EP.
Fig. 5: Coherence of state after trajectories through the EP.

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Data availability

Data for the figures in this article are available via Zenodo at https://doi.org/10.5281/zenodo.15756785 (ref. 55). Source data are provided with this paper.

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References

  1. Goryachev, M. et al. High-cooperativity cavity QED with magnons at microwave frequencies. Phys. Rev. Appl. 2, 054002 (2014).

    Article  ADS  Google Scholar 

  2. Everts, J. R. et al. Ultrastrong coupling between a microwave resonator and antiferromagnetic resonances of rare-earth ion spins. Phys. Rev. B 101, 214414 (2020).

    Article  ADS  Google Scholar 

  3. Lambert, N. J., Haigh, J. A. & Ferguson, A. J. Identification of spin wave modes in yttrium iron garnet strongly coupled to a co-axial cavity. J. Appl. Phys. 117, 053910 (2015).

    Article  ADS  Google Scholar 

  4. Tabuchi, Y. et al. Hybridizing ferromagnetic magnons and microwave photons in the quantum limit. Phys. Rev. Lett. 113, 083603 (2014).

    Article  ADS  Google Scholar 

  5. Zhang, X., Zou, C.-L., Jiang, L. & Tang, H. X. Strongly coupled magnons and cavity microwave photons. Phys. Rev. Lett. 113, 156401 (2014).

    Article  ADS  Google Scholar 

  6. Lachance-Quirion, D., Tabuchi, Y., Gloppe, A., Usami, K. & Nakamura, Y. Hybrid quantum systems based on magnonics. Appl. Phys. Express 12, 070101 (2019).

    Article  ADS  Google Scholar 

  7. Zare Rameshti, B. et al. Cavity magnonics. Phys. Rep. 979, 1–61 (2022).

    Article  MathSciNet  ADS  Google Scholar 

  8. Tabuchi, Y. et al. Coherent coupling between a ferromagnetic magnon and a superconducting qubit. Science 349, 405 (2015).

    Article  MathSciNet  ADS  Google Scholar 

  9. Lachance-Quirion, D. et al. Entanglement-based single-shot detection of a single magnon with a superconducting qubit. Science 367, 425 (2020).

    Article  ADS  Google Scholar 

  10. Lambert, N. J., Haigh, J. A., Langenfeld, S., Doherty, A. C. & Ferguson, A. J. Cavity-mediated coherent coupling of magnetic moments. Phys. Rev. A 93, 021803 (2016).

    Article  ADS  Google Scholar 

  11. Wang, Y.-P. et al. Nonreciprocity and unidirectional invisibility in cavity magnonics. Phys. Rev. Lett. 123, 127202 (2019).

    Article  ADS  Google Scholar 

  12. Zhang, X., Galda, A., Han, X., Jin, D. & Vinokur, V. M. Broadband nonreciprocity enabled by strong coupling of magnons and microwave photons. Phys. Rev. Appl. 13, 044039 (2020).

    Article  ADS  Google Scholar 

  13. Zhang, D., Luo, X.-Q., Wang, Y.-P., Li, T.-F. & You, J. Q. Observation of the exceptional point in cavity magnon-polaritons. Nat. Commun. 8, 1368 (2017).

    Article  ADS  Google Scholar 

  14. Liu, H. et al. Observation of exceptional points in magnonic parity-time symmetry devices. Sci. Adv. 5, eaax9144 (2019).

    Article  ADS  Google Scholar 

  15. Zhang, X., Ding, K., Zhou, X., Xu, J. & Jin, D. Experimental observation of an exceptional surface in synthetic dimensions with magnon polaritons. Phys. Rev. Lett. 123, 237202 (2019).

    Article  ADS  Google Scholar 

  16. Cao, Y. & Yan, P. Exceptional magnetic sensitivity of 𝒫⁢𝒯-symmetric cavity magnon polaritons. Phys. Rev. B 99, 214415 (2019).

    Article  ADS  Google Scholar 

  17. Harder, M., Yao, B. M., Gui, Y. S. & Hu, C.-M. Coherent and dissipative cavity magnonics. J. Appl. Phys. 129, 201101 (2021).

    Article  ADS  Google Scholar 

  18. Hurst, H. M. & Flebus, B. Non-Hermitian physics in magnetic systems. J. Appl. Phys. 132, 220902 (2022).

    Article  ADS  Google Scholar 

  19. Qian, J. et al. Non-Hermitian control between absorption and transparency in perfect zero-reflection magnonics. Nat. Commun. 14, 3437 (2023).

    Article  ADS  Google Scholar 

  20. Wang, C. et al. Enhancement of magnonic frequency combs by exceptional points. Nat. Phys. 20, 1139 (2024).

    Article  Google Scholar 

  21. Vitanov, N. V., Rangelov, A. A., Shore, B. W. & Bergmann, K. Stimulated Raman adiabatic passage in physics, chemistry, and beyond. Rev. Mod. Phys. 89, 015006 (2017).

    Article  ADS  Google Scholar 

  22. Xu, J. et al. Floquet cavity electromagnonics. Phys. Rev. Lett. 125, 237201 (2020).

    Article  ADS  Google Scholar 

  23. Qi, S.-F & Jing, J. Floquet generation of a magnonic NOON state. Phys. Rev. A 107, 013702 (2023).

    Article  ADS  Google Scholar 

  24. Yang, Y., Xiao, Y. & Hu, C.-M. Theory of Floquet-driven dissipative cavity magnonics. Phys. Rev. B 107, 054413 (2023).

    Article  ADS  Google Scholar 

  25. Zhang, F.-Y., Wu, Q.-C. & Yang, C.-P. Non-Hermitian shortcut to adiabaticity in Floquet cavity electromagnonics. Phys. Rev. A 106, 012609 (2022).

    Article  ADS  Google Scholar 

  26. Zhu, X., Xia, R. & Xu, L. Floquet-engineering magnonic NOON states with performance improved by soft quantum control. Quantum Inf. Process. 22, 454 (2023).

    Article  MathSciNet  ADS  Google Scholar 

  27. El-Ganainy, R. et al. Non-Hermitian physics and PT symmetry. Nat. Phys. 14, 11 (2018).

    Article  Google Scholar 

  28. Özdemir, S. K., Rotter, S., Nori, F. & Yang, L. Parity-time symmetry and exceptional points in photonics. Nat. Mater. 18, 783 (2019).

    Article  ADS  Google Scholar 

  29. Peng, B. et al. Parity–time-symmetric whispering-gallery microcavities. Nat. Phys. 10, 394 (2014).

    Article  Google Scholar 

  30. Dietz, B. et al. Rabi oscillations at exceptional points in microwave billiards. Phys. Rev. E 75, 027201 (2007).

    Article  ADS  Google Scholar 

  31. Doppler, J. et al. Dynamically encircling an exceptional point for asymmetric mode switching. Nature 537, 76 (2016).

    Article  ADS  Google Scholar 

  32. Partanen, M. et al. Exceptional points in tunable superconducting resonators. Phys. Rev. B 100, 134505 (2019).

    Article  ADS  Google Scholar 

  33. Xu, H., Mason, D., Jiang, L. & Harris, J. G. E. Topological energy transfer in an optomechanical system with exceptional points. Nature 537, 80 (2016).

    Article  ADS  Google Scholar 

  34. Zhang, J. et al. A phonon laser operating at an exceptional point. Nat. Photon. 12, 479 (2018).

    Article  ADS  Google Scholar 

  35. Stehmann, T., Heiss, W. D. & Scholtz, F. G. Observation of exceptional points in electronic circuits. J. Phys. A 37, 7813 (2004).

    Article  MathSciNet  ADS  Google Scholar 

  36. Choi, Y., Hahn, C., Yoon, J. W. & Song, S. H. Observation of an anti-PT-symmetric exceptional point and energy-difference conserving dynamics in electrical circuit resonators. Nat. Commun. 9, 2182 (2018).

    Article  ADS  Google Scholar 

  37. Choi, Y., Yoon, J. W., Hong, J. K., Ryu, Y. & Song, S. H. Direct observation of time-asymmetric breakdown of the standard adiabaticity around an exceptional point. Commun. Phys. 3, 1 (2020).

    Article  Google Scholar 

  38. Yoon, J. W. et al. Time-asymmetric loop around an exceptional point over the full optical communications band. Nature 562, 86 (2018).

    Article  ADS  Google Scholar 

  39. Feilhauer, J. et al. Encircling exceptional points as a non-Hermitian extension of rapid adiabatic passage. Phys. Rev. A 102, 040201 (2020).

    Article  ADS  Google Scholar 

  40. Jiang, X. et al. Coherent control of chaotic optical microcavity with reflectionless scattering modes. Nat. Phys. 20, 109–115 (2024).

    Article  Google Scholar 

  41. Schumer, A. et al. Topological modes in a laser cavity through exceptional state transfer. Science 375, 884 (2022).

    Article  ADS  Google Scholar 

  42. Ergoktas, M. S. et al. Topological engineering of terahertz light using electrically tunable exceptional point singularities. Science 376, 184 (2022).

    Article  ADS  Google Scholar 

  43. Wang, K., Dutt, A., Wojcik, C. C. & Fan, S. Topological complex-energy braiding of non-Hermitian bands. Nature 598, 59 (2021).

    Article  ADS  Google Scholar 

  44. Patil, Y. S. S. et al. Measuring the knot of non-Hermitian degeneracies and non-commuting braids. Nature 607, 271 (2022).

    Article  ADS  Google Scholar 

  45. Rao, Z. et al. Braiding reflectionless states in non-Hermitian magnonics. Nat. Phys. 20, 1904 (2024).

    Article  Google Scholar 

  46. Morris, R. G. E., van Loo, A. F., Kosen, S. & Karenowska, A. D. Strong coupling of magnons in a YIG sphere to photons in a planar superconducting resonator in the quantum limit. Sci. Rep. 7, 11511 (2017).

    Article  ADS  Google Scholar 

  47. Walker, L. R. Magnetostatic modes in ferromagnetic resonance. Phys. Rev. 105, 390 (1957).

    Article  ADS  Google Scholar 

  48. Fletcher, P., Solt, I. H. & Bell, R. Identification of the magnetostatic modes of ferrimagnetic resonant spheres. Phys. Rev. 114, 739 (1959).

    Article  ADS  Google Scholar 

  49. Harder, M. et al. Level attraction due to dissipative magnon-photon coupling. Phys. Rev. Lett. 121, 137203 (2018).

    Article  ADS  Google Scholar 

  50. Gilary, I., Mailybaev, A. A. & Moiseyev, N. Time-asymmetric quantum-state-exchange mechanism. Phys. Rev. A 88, 010102 (2013).

    Article  ADS  Google Scholar 

  51. Uzdin, R., Mailybaev, A. & Moiseyev, N. On the observability and asymmetry of adiabatic state flips generated by exceptional points. J. Phys. A 44, 435302 (2011).

    Article  MathSciNet  ADS  Google Scholar 

  52. Nasari, H. et al. Observation of chiral state transfer without encircling an exceptional point. Nature 605, 256 (2022).

    Article  ADS  Google Scholar 

  53. Hassan, A. U. et al. Chiral state conversion without encircling an exceptional point. Phys. Rev. A 96, 052129 (2017).

    Article  ADS  Google Scholar 

  54. Znojil, M. Passage through exceptional point: case study. Proc. Math. Phys. Eng. Sci. 476, 20190831 (2020).

    MathSciNet  Google Scholar 

  55. Lambert, N. J., Schumer, A., Longdell, J. J., Rotter, S. & Schwefel, H. G. L. Data for figures in ‘Coherent control of magnon-polaritons using an exceptional point’. Zenodo https://doi.org/10.5281/zenodo.15756785 (2025).

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Acknowledgements

N.J.L. is supported by Marsden Fund grant number 24-UOO-153. N.J.L acknowledges discussions with J. Squire.

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Authors and Affiliations

  1. Department of Physics, University of Otago, Dunedin, New Zealand

    N. J. Lambert, J. J. Longdell & H. G. L. Schwefel

  2. The Dodd–Walls Centre for Photonic and Quantum Technologies, Dunedin, New Zealand

    N. J. Lambert, J. J. Longdell & H. G. L. Schwefel

  3. Institute for Theoretical Physics, Vienna University of Technology (TU Wien), Vienna, Austria

    A. Schumer & S. Rotter

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Contributions

N.J.L. conceptualized the experiment and performed the implementation and measurement. The paper was written by N.J.L. with input from all authors. A.S. and S.R. carried out the theoretical calculations and provided conceptual input. The work was supervised by J.J.L., S.R. and H.G.L.S.

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Correspondence to N. J. Lambert.

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Nature Physics thanks Zhenghua An, Benedetta Flebus and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Data for all τ values in Supplementary Fig. 2.

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Lambert, N.J., Schumer, A., Longdell, J.J. et al. Coherent control of magnon–polaritons using an exceptional point. Nat. Phys. 21, 1570–1577 (2025). https://doi.org/10.1038/s41567-025-02998-3

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