Nonreciprocal light-matter interaction in a plasmonic-photonic cavity with chiral exceptional points
Phys. Rev. A 113, 023710 – Published 13 February, 2026
DOI: https://doi.org/10.1103/9qbh-lkh7
Abstract
Nonreciprocity enables unidirectional energy transfer that facilitates development of quantum devices with high efficiency, strong robustness, and advanced functionalities. For light-matter interaction, the implementation of nonreciprocity is limited by the fundamental principle of time-reversal symmetry in electromagnetics. Here we demonstrate that the nonreciprocal light-matter interaction can be realized at the single-photon level between a linearly polarized quantum emitter (QE) and two degenerate whispering gallery modes of hybrid plasmonic-photonic cavity featuring chiral exceptional points (EPs). This tripartite nonreciprocal interaction results from the chiral energy flow created by balancing the coherent and dissipative couplings: The destructive interference of the plasmon-mediated dissipative interaction and its coherent counterpart give rise to unidirectional coupling between the QE and cavity modes, while the unidirectional coupling between two cavity modes is achieved by the destructive interference of dissipative interactions induced by plasmon and chiral EPs, where the phase of light emerges as an additional degree of freedom to flexibly tune the coupling coefficient in a complex space. Controlling the direction of chiral energy flow through the destructive interference of coherent and dissipative couplings results in nonreciprocal QE-cavity interaction, which is evidenced by the population dynamics with different configurations of initial excitation. As a quantum-optics application, we show that the established nonreciprocity enables the proposed hybrid cavity to serve as a multiplexing quantum light source for single photons and two photons generated in the traveling-wave modes with opposite propagating directions. Our results provide a feasible scheme for the experimental realization of nonreciprocal light-matter interaction in nanophotonic systems, which holds great potential in building nonreciprocal quantum devices for future applications in quantum computing and quantum information processing.
