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Parity–time-symmetric whispering-gallery microcavities

Nature Physics volume 10, pages 394398 (2014) | Download Citation

Abstract

Optical systems combining balanced loss and gain provide a unique platform to implement classical analogues of quantum systems described by non-Hermitian parity–time (PT)-symmetric Hamiltonians. Such systems can be used to create synthetic materials with properties that cannot be attained in materials having only loss or only gain. Here we report PT-symmetry breaking in coupled optical resonators. We observed non-reciprocity in the PT-symmetry-breaking phase due to strong field localization, which significantly enhances nonlinearity. In the linear regime, light transmission is reciprocal regardless of whether the symmetry is broken or unbroken. We show that in one direction there is a complete absence of resonance peaks whereas in the other direction the transmission is resonantly enhanced, a feature directly associated with the use of resonant structures. Our results could lead to a new generation of synthetic optical systems enabling on-chip manipulation and control of light propagation.

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Acknowledgements

This work is supported by Army Research Office grant No. W911NF-12-1-0026. C.M.B. is supported by US Department of Energy grant No. DE-FG02-91ER40628. F.N. is partially supported by the RIKEN iTHES Project, MURI Center for Dynamic Magneto-Optics, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics and the JSPS through its FIRST program. F.L. and G.L.L. are supported by the National Natural Science Foundation of China (Grant Nos 11175094, 91221205), the National Basic Research Program of China (Grant No. 2011CB921602), and the  Collaborative Innovation Center of Quantum Matter, Beijing, China.

Author information

Author notes

    • Bo Peng
    •  & Şahin Kaya Özdemir

    These authors contributed equally to this work.

Affiliations

  1. Department of Electrical and Systems Engineering, Washington University, St Louis, Missouri 63130, USA

    • Bo Peng
    • , Şahin Kaya Özdemir
    • , Fuchuan Lei
    • , Faraz Monifi
    •  & Lan Yang
  2. State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China

    • Fuchuan Lei
    •  & Gui Lu Long
  3. Department of Physics, Washington University, St Louis, Missouri 63130, USA

    • Mariagiovanna Gianfreda
    •  & Carl M. Bender
  4. Dipartimento di Matematica e Fisica Ennio De Giorgi, Universita del Salento and I.N.F.N. Sezione di Lecce, Via Arnesano I-73100 Lecce, Italy

    • Mariagiovanna Gianfreda
  5. Tsinghua National Laboratory for Information Science and Technology, Beijing 100084, China

    • Gui Lu Long
  6. Department of Electrical Engineering, Stanford University, Stanford, California 94305, USA

    • Shanhui Fan
  7. Center for Emergent Matter Science, RIKEN, Saitama 351-0198, Japan

    • Franco Nori
  8. Physics Department, University of Michigan, Ann Arbor Michigan 48109-1040, USA

    • Franco Nori

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Contributions

S.K.O. and L.Y. conceived the idea and designed the experiments; B.P. performed the experiments with help from F.L., F.M. and S.K.O. Theoretical background and simulations were provided by F.L., F.M., M.G., C.M.B., S.F. and F.N. All authors discussed the results, and S.K.O. and L.Y. wrote the manuscript with inputs from all authors. L.Y. supervised the project.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Şahin Kaya Özdemir or Lan Yang.

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DOI

https://doi.org/10.1038/nphys2927

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