Bonn 2025 – scientific programme

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QI: Fachverband Quanteninformation

QI 29: Quantum Information: Concepts and Methods I

QI 29.8: Talk

Thursday, March 13, 2025, 13:00–13:15, HS IV

Quantifying the rotating-wave approximation of the Dicke model — •Leonhard Richter, Daniel Burgarth, and Davide Lonigro — Department Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen, Germany

We analytically find quantitative, non-perturbative bounds to the validity of the rotating-wave approximation (RWA) for the multi-atom generalization of the quantum Rabi model: the Dicke model. Precisely, we bound the norm of the difference between the evolutions of states generated by the Dicke model and its rotating-wave approximated counterpart, that is, the Tavis-Cummings model. The intricate role of the parameters of the model in determining the bounds is discussed and compared with numerical results. Our bounds are intrinsically state-dependent and, in particular, are significantly different in the cases of entangled and non-entangled states; this behaviour also seems to be confirmed by the numerics.

Keywords: Rotating-wave approximation; Dicke model; Tavis-Cummings model; Light-matter interaction