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Anti-parity–time symmetry with flying atoms

Nature Physics volume 12, pages 1139–1145 (2016)Cite this article

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Abstract

The recently developed notion of parity–time (PT) symmetry in optical systems has spawned intriguing prospects. So far, most experimental implementations have been reported in solid-state systems. Here, we report the first experimental demonstration of optical anti-PT symmetry—the counterpart of conventional PT symmetry—in a warm atomic-vapour cell. Rapid coherence transport via flying atoms leads to a dissipative coupling between two long-lived atomic spin waves, allowing for the observation of the essential features of anti-PT symmetry with unprecedented precision on the phase-transition threshold, as well as refractionless light propagation. Moreover, we show that a linear or nonlinear interaction between the two spatially separated beams can be achieved. Our results advance non-Hermitian physics by bridging to the field of atomic, molecular and optical physics, where new phenomena and applications in quantum and nonlinear optics aided by (anti-)PT symmetry could be anticipated.

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Figure 1: Anti-PT-symmetric optics via rapid atomic-coherence transport in a warm 87Rb vapour cell.
Figure 2: Representative transmission spectra of output probe light in anti-PT symmetry.
Figure 3: Anti-PT supermodes in coupled-EIT channels in a homogeneous, warm 87Rb vapour cell.
Figure 4: Theoretical calculation and experimental demonstration of refractionless propagation of light (n = 1 + Re[χ]/2 = 1) assisted by anti-PT symmetry in the symmetry-unbroken regime.
Figure 5: Observation of interference between two EIT channels by manipulating the relative-phase difference among laser beams.
Figure 6: Proposal for effective nonlinear interaction between two weak-probe fields aided by anti-PT-symmetric coupling of spin waves.

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Acknowledgements

We are grateful to V. V. Albert for reading the manuscript. This work is supported by National Key Research Program of China under Grant No. 2016YFA0302000, and NNSFC under Grant No. 11322436. J.W. and L.J. acknowledge funding support from the ARO, the AFSOR MURI, the ARL CDQI program, the Alfred P. Sloan Foundation, and the David and Lucile Packard Foundation.

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Authors and Affiliations

  1. Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), Fudan University, Shanghai 200433, China

    Peng Peng, Wanxia Cao, Ce Shen, Weizhi Qu & Yanhong Xiao

  2. Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA

    Jianming Wen & Liang Jiang

  3. Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China

    Yanhong Xiao

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  1. Peng Peng
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Contributions

J.W., L.J. and Y.X. conceived the idea. Y.X. supervised the project. P.P. performed the experiment. W.C., P.P. and L.J. did the theoretical derivation and numerical calculations with contributions from all other authors. J.W., L.J. and Y.X. wrote the manuscript with contributions from all other authors. All contributed to the discussion of the project and analysis of the experimental data.

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Correspondence to Jianming Wen, Liang Jiang or Yanhong Xiao.

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Peng, P., Cao, W., Shen, C. et al. Anti-parity–time symmetry with flying atoms. Nature Phys 12, 1139–1145 (2016). https://doi.org/10.1038/nphys3842

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