Speaker
Description
The present work examines light-matter interactions in a two-dimensional electron gas formed in a periodic lateral superlattice, subjected to a perpendicular homogeneous magnetic field, and embedded in a cylindrical far-infrared photon cavity. The electronic states are constructed in the magneto-translational invariant Ferrari basis, which naturally captures the magnetic Bloch structure of the system. Within this framework, photon replicas, as well as para- and diamagnetic contributions to the coupled electron-photon dynamics, are treated on equal footing.
The calculations are carried out using a quantum electrodynamics density functional theory (QED-DFT) approach combined with a tensor-product (TP) representation of electron and photon states. While electron-electron interactions are incorporated at the level of QED-DFT, the electron-photon coupling is treated nonperturbatively via exact diagonalization (configuration interaction) within each self-consistent iteration. This allows for a consistent description of photon-dressed electronic states and their dynamical response.
The coherent dynamics provides a controlled setting to identify resonant and off-resonant excitation regimes, which are essential for application to open-system descriptions where environmental coupling and relaxation processes are included.
The results reveal a clear distinction between resonant and off-resonant driving conditions. In the near-resonant regime, the system exhibits a pronounced and sustained increase in total energy and photon occupation, indicating efficient energy transfer from the external drive into photon-dressed collective modes. In contrast, for detuned excitation, the dynamics remain bounded and are characterized by coherent oscillations with pronounced beating patterns, reflecting reversible energy exchange between the electronic and photonic degrees of freedom.
These observations suggest that detuning plays a critical role in controlling the long-time dynamics of the driven system. Off-resonant driving suppresses sustained energy accumulation and stabilizes the dynamics, leading to behavior that qualitatively resembles a weakly dissipative response. This highlights the importance of frequency and phase matching between the external drive and the underlying photon-dressed excitation spectrum, and provides a physically transparent reference for assessing the impact of dissipation in open-system extensions.