Non-Markovian nonreciprocal interactions in waveguide-based systems
Phys. Rev. A 113, 023703 – Published 9 February, 2026
DOI: https://doi.org/10.1103/fwdy-lccn
Abstract
In this work we investigate nonreciprocal interactions in waveguide-based systems within the non-Markovian regime. We show that by designing the coherent interaction between two spatially separated small atoms in the form of steplike modulations and by properly balancing the strengths of coherent and waveguide-induced dissipative interactions, it is possible to achieve a highly efficient unidirectional interaction between these two atoms. The resulting asymmetric instantaneous population distributions arise purely from the mathematical structure of the system and are influenced by multiple factors, including the time delay, phase, amplitude of the coherent interaction, and form of the steplike modulations. We further extend our analysis to giant-atom systems with various topological configurations. Our results reveal that, unlike in the case of small atoms, energy not only can be transferred asymmetrically between two giant atoms but also can be preserved without decay in the long-time limit under appropriate conditions. By incorporating temporal effects, this work provides a valuable reference for exploring long-distance unidirectional energy exchange in waveguide-based systems.
