Rabi oscillation and fractional population via the bound states in the continuum in a giant-atom waveguide QED setup
Hongwei Yu, Xiaojun Zhang, Zhihai Wang, Jin Wang · Physical Review A · 2025
We study the dynamics of two giant atoms interacting with a coupled resonator waveguide (CRW) beyond the Markovian approximation. The distinct atomic configurations determine the number of bound states in the continuum (BICs), leading to different dynamical behaviors. Our results show that when the system supports two BICs, Rabi oscillations dominate the dynamics, whereas fractional population dynamics emerge in the presence of a single BIC. The connection between these dynamics and the existence of BICs is further verified by analyzing the photonic distribution in the CRW during time evolution. These findings challenge the conventional notion that the environment always induces dissipation and decoherence. Instead, the bound states in the CRW-emitter coupled system can suppress complete dissipation of the emitters. We also quantitatively illustrate the memory effect of the waveguide, which serves as the environment of the giant-atom feature that can only be captured within our non-Markovian treatment. This work offers an effective approach for controlling dissipative dynamics in open quantum systems.