Engineering Atom-Photon Hybridization with Density-Modulated Atomic Ensembles in Coupled Cavities

Abstract

Radiation-matter hybridization allows atoms to serve as mediators of effective interactions between light modes and, conversely, to interact among themselves via light. Here we exploit the spatial structure of atomic ensembles to control the coupling between modes of distinct cavities, thereby reshaping the resulting atom-photon spectra. We show that extended homogeneous clouds suppress mode-mode couplings through destructive interference, whereas grated clouds can preserve them under specific Bragg conditions. This leads to mode-mode spectral subsplittings, where collectivity arises not only from the atom number but also from the ability to tune modes of different cavities independently. Our results establish spatially engineered atomic ensembles as a pathway to selective photon transfer between modes and precise control of many-body complexity.

Figures (2)

• Figure 1: Two crossed cavity modes couple to Gaussian atomic distributions of two-level atoms, with and without a grating, in the intersecting region where the light fields combine. A pump field inject photons into mode 1 (in light coral) on the left, while detectors collect the leaking light from the mirrors on the right side.
• Figure 2: Amplitudes of pumped (a–b in light coral) and nonpumped (d–e in light peach) modes as functions of $\Delta/\Gamma$ and width $kR$, for pure Gaussian (first column) and grated (second column) atomic distributions. These simulations were realized for $g_1=g_2=0.8\Gamma$. (c) Amplitude of the pumped mode as a function of $\Delta$ and $g_1$, with $g_2=0.5\Gamma$. (f) Resonances $\mathcal{G}{\pm}$ as functions of $g_1$ and $g_2$. For all panels, the crossing modes are $\mathbf{k}_{1}=k(-1,1)/\sqrt{2}$ and $\mathbf{k}_{2}=k(1,1)/\sqrt{2}$, corresponding to two cavities rotated by an angle $\pi/2$ and $\mathbf{q}=(\mathbf{k}_{1}+\mathbf{k}_{2})/2=k(0,1)/\sqrt{2}$, with $\kappa_1=1\Gamma$, $\kappa_2=4\Gamma$, $\eta=0.01\Gamma$, $N=10^4$, and $\Delta_1=\Delta_2=0$.