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arXiv · 2605.20542

Mean-field and fluctuation dynamics in off-resonant two-mode atom-field interactions

Luis Medina-Dozal·Alejandro R. Urzúa·Carlos A. González-Gutiérrez·José Récamier
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Abstract

We study a two-level system coupled to two quantized electromagnetic modes within the Jaynes-Cummings framework. While the single-mode model is exactly solvable due to its conserved excitation number, yielding finite-dimensional invariant subspaces, the two-mode model extension presents a fundamental challenge: although the total excitation number remains conserved, each invariant subspace is infinite-dimensional, preventing a closed-form analytical solution. Our scheme separates the dynamics into a dominant, exactly solvable semiclassical component, the atom interacting with the mean fields of both modes, and treats the remaining quantum fluctuations through a sequence of unitary transformations that preserve essential quantum features. We validate our approach through direct comparison with numerical solutions, focusing on the non-resonant regime where multiple detunings give rise to rich interference effects and multi-timescale dynamics inaccessible to standard approximations. The method accurately reproduces atomic inversion, field observables, and fidelity over relevant timescales, while remaining computationally efficient.

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Luis Medina-Dozal, Alejandro R. Urzúa, Carlos A. González-Gutiérrez, José Récamier. 2026-05-19. Mean-field and fluctuation dynamics in off-resonant two-mode atom-field interactions. https://arxiv.org/abs/2605.20542

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