Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Symmetry-breaking-induced plasmonic exceptional points and nanoscale sensing


Singularities of open systems, known as exceptional points (EPs), have been shown to exhibit increased sensitivities, but the observation of EPs has so far been limited to wavelength-scaled systems subject to the diffraction limit. Plasmons, the collective oscillations of free electrons coupled to photons, shrink the wavelength of light to electronic and molecular length scales. We propose a novel approach to EPs based on spatial symmetry breaking and report their observation in plasmonics at room temperature. The plasmonic EPs are based on the hybridization of detuned resonances in multilayered plasmonic structures to reach a critical complex coupling rate between nanoantenna arrays, resulting in the simultaneous coalescence of the resonances and loss rates. Their utility as sensors of anti-immunoglobulin G, the most abundant immunoglobulin isotype in human serum, is evaluated. Our work opens the way to a new class of nanoscale devices, sensors and imagers based on topological polaritonic effects.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Fig. 1: Multilayered periodic plasmonic structure supporting EPs.
Fig. 2: Plasmonic and symmetry-dependent hybridization scheme of resonances and loss rates.
Fig. 3: Experimental observation of plasmonic EP.
Fig. 4: Immuno-assay nanosensing with a plasmonic EP.

Data availability

The data presented in Figs. 2g,h, 3a–d and 4 are available as Source Data. All other data that support the plots within this paper and other findings of this study are available from the corresponding author on reasonable request.

Code availability

The computer codes that support the plots within this paper and other findings of this study are available from the corresponding author on reasonable request.


  1. Degen, C. L., Reinhard, F. & Cappellaro, P. Quantum sensing. Rev. Mod. Phys. 89, 035002 (2017).

    Article  ADS  MathSciNet  Google Scholar 

  2. Heiss, W. D. Exceptional points of non-Hermitian operators. J. Phys. Math. Gen. 37, 2455–2464 (2004).

    Article  ADS  MathSciNet  Google Scholar 

  3. Berry, M. V. Physics of nonhermitian degeneracies. Czech. J. Phys. 54, 1039–1047 (2004).

    Article  ADS  Google Scholar 

  4. Bender, C. M., Brody, D. C. & Jones, H. F. Complex extension of quantum mechanics. Phys. Rev. Lett. 89, 270401 (2002).

    Article  MathSciNet  Google Scholar 

  5. Carusotto, I. & Ciuti, C. Quantum fluids of light. Rev. Mod. Phys. 85, 299–366 (2013).

    Article  ADS  Google Scholar 

  6. Dembowski, C. et al. Experimental observation of the topological structure of exceptional points. Phys. Rev. Lett. 86, 787–790 (2001).

    Article  ADS  Google Scholar 

  7. Choi, Y. et al. Quasieigenstate coalescence in an atom-cavity quantum composite. Phys. Rev. Lett. 104, 153601 (2010).

    Article  ADS  Google Scholar 

  8. Ding, K., Ma, G., Xiao, M., Zhang, Z. Q. & Chan, C. T. Emergence, coalescence, and topological properties of multiple exceptional points and their experimental realization. Phys. Rev. X 6, 021007 (2016).

    Google Scholar 

  9. Makris, K. G., Ge, L. & Türeci, H. E. Anomalous transient amplification of waves in non-normal photonic media. Phys. Rev. X 4, 041044 (2014).

    Google Scholar 

  10. Cui, H. X. et al. Exceptional points in extraordinary optical transmission through dual subwavelength metallic gratings. Opt. Express 21, 13368–13379 (2013).

    Article  ADS  Google Scholar 

  11. Kodigala, A., Lepetit, T. & Kanté, B. Exceptional points in three-dimensional plasmonic nanostructures. Phys. Rev. B 94, 201103(R) (2016).

    Article  ADS  Google Scholar 

  12. Lourenco-Martins, H., Das, P., Tizei, L. H. G., Weil, R. & Kociak, M. Self-hybridization within non-Hermitian localized plasmonic system. Nat. Phys. 14, 360–364 (2018).

    Article  Google Scholar 

  13. Wiersig, J. Enhancing the sensitivity of frequency and energy splitting detection by using exceptional points: application to microcavity sensors for single particle detection. Phys. Rev. Lett. 112, 203901 (2014).

    Article  ADS  Google Scholar 

  14. Gao, T. et al. Observation of non-Hermitian degeneracies in a chaotic exciton-polariton billiard. Nature 526, 554–558 (2015).

    Article  ADS  Google Scholar 

  15. Doppler, J. et al. Dynamically encircling an exceptional point for asymmetric mode switching. Nature 537, 76–79 (2016).

    Article  ADS  Google Scholar 

  16. Xu, H., Mason, D., Jiang, L. & Harris, J. G. E. Topological energy transfer in an optomechanical system with exceptional points. Nature 537, 80–83 (2016).

    Article  ADS  Google Scholar 

  17. Miao, P. et al. Orbital angular momentum microlaser. Science 353, 464–467 (2016).

    Article  ADS  Google Scholar 

  18. Hodaei, H. et al. Enhanced sensitivity at higher-order exceptional points. Nature 548, 187–191 (2017).

    Article  ADS  Google Scholar 

  19. Chen, W., Özdemir, S. K., Zhao, G., Wiersig, J. & Yang, L. Exceptional points enhance sensing in an optical microcavity. Nature 548, 192–196 (2017).

    Article  ADS  Google Scholar 

  20. Zhen, B. et al. Spawning rings of exceptional points out of Dirac cones. Nature 525, 354–358 (2015).

    Article  ADS  Google Scholar 

  21. Yoon, J. W. et al. Time-asymmetric loop around an exceptional point over the full optical communications band. Nature 562, 86–90 (2018).

    Article  ADS  Google Scholar 

  22. Pick, A. et al. General theory of spontaneous emission near exceptional points. Opt. Express 25, 12325–12348 (2017).

    Article  ADS  Google Scholar 

  23. Lai, Y.-H., Lu, Y.-K., Suh, M.-G. & Vahala, K. Observation of the exceptional-point-enhanced Sagnac effect. Nature 576, 65–69 (2019).

    Article  ADS  Google Scholar 

  24. Dong, Z., Li, Z., Yang, F., Qiu, C.-W. & Ho, J. S. Sensitive readout of implantable microsensors using a wireless system locked to an exceptional point. Nat. Electron. 2, 335–342 (2019).

    Article  Google Scholar 

  25. Kazemi, H., Nada, M. Y., Maddaleno, F. & Capolino, F. Experimental demonstration of exceptional points of degeneracy in linear time periodic systems and exceptional sensitivity. Preprint at (2019).

  26. Zhao, H., Chen, Z., Zhao, R. & Feng, L. Exceptional point engineered glass slide for microscopic thermal mapping. Nat. Commun. 9, 1764 (2018).

    Article  ADS  Google Scholar 

  27. Alaeian, H. & Dionne, J. A. Parity-time-symmetric plasmonic metamaterials. Phys. Rev. A 89, 033829 (2014).

    Article  ADS  Google Scholar 

  28. Vidarsson, G., Dekkers, G. & Rispens, T. IgG subclasses and allotypes: from structure to effector functions. Front. Immunol. 5, 520 (2014).

    Article  Google Scholar 

  29. Prodan, E., Radloff, C., Halas, N. J. & Nordlander, P. A hybridization model for the plasmon response of complex nanostructures. Science 302, 419–422 (2003).

    Article  ADS  Google Scholar 

  30. Liu, N., Hentschel, M., Weiss, T., Alivisatos, A. P. & Giessen, H. Three-dimensional plasmon rulers. Science 332, 1407–1410 (2011).

    Article  ADS  Google Scholar 

  31. Kanté, B. et al. Symmetry breaking and optical negative index of closed nanorings. Nat. Commun. 3, 1180 (2012).

    Article  ADS  Google Scholar 

  32. Wu, C. et al. Fano-resonant asymmetric metamaterials for ultrasensitive spectroscopy and identification of molecular monolayers. Nat. Mater. 11, 69–75 (2012).

    Article  ADS  Google Scholar 

  33. Brongersma, M. L. & Shalaev, V. M. The case for plasmonics. Science 328, 440–441 (2010).

    Article  ADS  Google Scholar 

  34. Meinzer, N., Barnes, W. L. & Hooper, I. R. Plasmonic meta-atoms and metasurfaces. Nat. Photon. 8, 889–898 (2014).

    Article  ADS  Google Scholar 

  35. Kabashin, A. V. et al. Plasmonic nanorod metamaterials for biosensing. Nat. Mater. 8, 867–871 (2009).

    Article  ADS  Google Scholar 

  36. Glover, F. A. & Goulden, J. D. S. Relationship between refractive index and concentration of solutions. Nature 200, 1165–1166 (1963).

    Article  ADS  Google Scholar 

  37. Cetin, A. E. et al. Plasmonic nanohole arrays on a robust hybrid substrate for highly sensitive label-free biosensing. ACS Photon. 8, 1167–1174 (2015).

    Article  Google Scholar 

  38. Sreekanth, K. V. et al. Extreme sensitivity biosensing platform based on hyperbolic metamaterials. Nat. Mater. 15, 621–627 (2016).

    Article  ADS  Google Scholar 

Download references


This research was supported by the National Science Foundation Career Award (ECCS-1554021) and the Office of Naval Research Young Investigator Award (N00014-17-1-2671) and the ONR JTO MRI Award (N00014-17-1-2442). The work was partially supported by the DARPA DSO-NLM Program no. HR00111820038 and the US Department of Energy (DOE) (grant no. DE-EE0007341). The work was performed in part at the San Diego Nanotechnology Infrastructure, a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the National Science Foundation (grant no. ECCS-1542148). We thank M. Montero for technical assistance regarding the fabrication.

Author information

Authors and Affiliations



B.K. conceived the project and guided the theoretical and experimental investigations. J.-H.P. and L.-Y.H. performed the simulations. J.-H.P. fabricated the samples. A.N. developed the setup and performed the measurements with J.-H.P. W.C. functionalized the samples under the guidance of Y.-H.L. and B.K. All authors contributed to discussions and manuscript writing.

Corresponding author

Correspondence to Boubacar Kanté.

Ethics declarations

Competing interests

The Regents of the University of California have filed a patent application (US Prov. App. 62/823,158) on technology related to the processes described in this article.

Additional information

Peer review information Nature Physics thanks Christos Argyropoulos, Jan Wiersig and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–21.

Source data

Source Data Fig. 2

Data of Fig. 2g,h

Source Data Fig. 3

Data of Fig. 3a–d

Source Data Fig. 4

Data of Fig. 4

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Park, JH., Ndao, A., Cai, W. et al. Symmetry-breaking-induced plasmonic exceptional points and nanoscale sensing. Nat. Phys. 16, 462–468 (2020).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing