Collective Chirped STIRAP in a Pair of Three-Level Atoms: Dressed-Manifold Dynamics and Compensation of the Rydberg-Rydberg Interaction-Induced Detuning
We investigate collective chirped stimulated Raman adiabatic passage (STIRAP) in a pair of identical three-level atoms using a symmetric six-state model. Numerical simulations reveal a pronounced oscillatory dependence of the population transfer to the doubly excited Rydberg state on the peak Rabi frequency, indicating dynamics beyond the conventional single-dark-state description of STIRAP. To identify the underlying mechanism, we develop a dressed-manifold description based on gauge-invariant projections onto nearly degenerate instantaneous dressed manifolds. The analysis demonstrates that the wavefunction remains predominantly confined to a two-dimensional dark manifold while becoming transiently coupled to a neighboring bright manifold during the pulse-overlap interval. We further show that in the dressed-manifold representation, the Rydberg-Rydberg interaction modifies the collective resonance structure while preserving the dark-bright manifold dynamics responsible for the oscillatory transfer; an appropriately chosen frequency chirp compensates the interaction-induced detuning and restores efficient population transfer. This dressed-manifold picture provides a consistent interpretation of oscillatory collective transfer and establishes a framework for controlling adiabatic dynamics in interacting multilevel systems by linearly chirped STIRAP, opening a route toward manifold-based control of Rydberg-mediated quantum gates, correlated-state preparation, and other coherent operations in interacting atomic systems.