There is an increasing interest in modeling transient light-matter interactions by means of mixed quantum-classical dynamics, where emitters are described quantum-mechanically and the optical fields classically. Incorporating light-matter coupling contributions through the Ehrenfest theorem has proven to strike an optimal balance between the model's accuracy and simplicity. However, as with all mixed quantum-classical models, a lack of zero-point fluctuations in the classical field prohibits a description of spontaneous emission. In this talk, I will demonstrate how zero-point fluctuations can be incorporated within Ehrenfest modeling by invoking dedicated classical oscillators drawn from the ground state of the optical wavefunction. By decoupling these oscillators from the ground state of the emitters, the unphysical drawing of energy from the field's zero-point fluctuations is eliminated, which would otherwise occur if Wigner sampling is being used. I will present results for a quantum emitter in a Fabry–Perot cavity, for which encouraging agreement is found compared to exact quantum modeling. This suggests that the resulting method holds great potential for transiently describing a wide array of optical phenomena, including pulse effects in nonlinear spectroscopy.

Ehrenfest modeling of spontaneous emission

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