Fig. 1.

The figure schematically illustrates a 2D optical cavity containing one atom, with a single electron. The coupling of the electron to the cavity mode at resonance frequency ${\omega }_{\alpha }$ and with electron–photon coupling strength ${\lambda }_{\alpha }$ modifies the dynamics of the electron density $n\left(\mathbf{r}t\right)$, which moves in the external potential $v_{\text{ext}}\left(\mathbf{r}t\right)$.