Single-photon scattering off a periodically modulated giant atom
Phys. Rev. A 113, 013731 – Published 22 January, 2026
DOI: https://doi.org/10.1103/fy3m-hngg
Abstract
Controllable single-photon scattering of a periodically modulated two-level giant atom indirectly coupled to a one-dimensional waveguide at two separate points via two single-mode cavities is investigated in both the Markovian and non-Markovian regimes. By using an effective Floquet Hamiltonian approach, we demonstrate how this architecture is capable of transcending various limitations of conventional static giant-atom systems. The periodic modulation serves as a dynamic controller that enables in situ reconfiguration of quantum interference, allowing a single device to be realized for multiple functions, including programmable Fano resonance lineshapes and dynamic switching between transmission and reflection at different frequencies. Notably, the cavity-mediated coupling facilitates the emergence of tunable multidip spectra even in the Markovian regime, a feature previously unattainable in giant atom-waveguide-only configurations without non-Markovian retardation. The underlying Floquet engineering generates dressed-state sidebands that effectively transform the giant atom-cavity structure into a dynamically controllable multilevel system, creating new pathways for photon control through interference among these synthetic states. In the non-Markovian regime, this modulation capability combines with retardation effects can be further used to produce dynamic controllable spectra with multiple peaks and dips. Perfect transmission or reflection with tunable ultranarrow or ultrawide scattering windows can be achieved. This work establishes a paradigm for dynamically reconfigurable quantum devices with promising applications in quantum routing, spectral shaping, and information processing.
