Non-reciprocal transmission in a non-Hermitian waveguide quantum electrodynamics system with non-reciprocal hopping

The non-reciprocal transmission was investigated in a one-dimensional plasmonic waveguide coupled to multiple two-level quantum emitters’ chain with non-reciprocal hopping coupling. The non-reciprocal transmission is originated from breaking time-reversal symmetry via the non-reciprocal hopping coupling between quantum emitters. The bidirectional non-reciprocal transmission was observed by appropriately modulating the phase shift and non-reciprocal hopping coupling between the two quantum emitters. In addition, unidirectional and dual-band non-reciprocal transmission could be achieved in the case of multiple quantum emitters. Our results could have potential applications in non-reciprocal optical devices, such as switches, single-photon transistors, isolators, and diodes.