Quantum Nonreciprocity and Nonreciprocal Photonic Devices Based on Giant Magnon Molecule

ABSTRACT We propose a scheme for realizing strong quantum nonreciprocity and nonreciprocal photonic devices mediated by the magnon‐photon coupling phase based on giant magnon molecule in both the Markovian and the non‐Markovian regimes, where the giant magnon molecule is composed of two coupled giant spin ensembles interacting with two waveguides. We reveal the hidden effective chirality of the system and further implement quantum nonreciprocity. In the Markovian regime, the perfect nonreciprocity of single photon transmission can be observed by tuning phase and its various values of work frequency points can be satisfied based on the regulation of magnon‐magnon coupling strength. We obtained a flexible frequency modulation single photon diode. It is also found that single photon targeted router with tunable routing direction and perfectly asymmetrical scattering effects including chiral scattering and nonreciprocal routing are realized. The coordinated modulation of the coupling phases and the accumulated phases caused by photon moving between two coupling points can complete single photon circulator with multiple circulating directions. In the non‐Markovian regime, single photon transmission exhibits multiple narrow nonreciprocal transmission windows. Multi‐frequency single photon targeted router, multiple narrow asymmetrical scattering effects windows, and multi‐frequency single photon circulator are further obtained. In addition, under specific conditions, non‐Markovianity can induce nonreciprocity and asymmetrical scattering effects that cannot occur in the Markovian regime. Non‐Markovianity induced single photon level quantum devices are further designed. Our results provide a promising for on‐chip single photon manipulation and have potential applications in integrated magnon‐based quantum network engineering.