Rydberg Excitons in the Presence of an Ultralow-Density Electron-Hole Plasma
Rydberg Excitons in the Presence of an Ultralow-Density Electron-Hole Plasma
We use two-color pump-probe spectroscopy to study Rydberg excitons in Cu$_2$O in the presence of free carriers injected by above-band-gap excitation. Already at plasma densities $\rho_\text{eh}$ below one hundredth electron-hole pair per \textmu m$^{3}$, the Rydberg exciton absorption lines are bleached while their energies remain constant, until they finally disappear, …