Strong microwave-induced cross-Kerr effect with Rydberg atoms at telecommunication wavelength

We experimentally demonstrate an effective interaction between telecommunication-wavelength optical photons and microwave photons, mediated by Rydberg atoms. A microwave-induced giant cross-Kerr effect is observed in a ${}^{85}\mathrm{Rb}$ vapor cell by our probing higher excited atomic states at the optical telecommunication band, and the measured third-order cross-Kerr coefficient ${\ensuremath{\chi}}^{(3)}$ can reach approximately $1\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.2em}{0ex}}{\mathrm{m}}^{2}/{\mathrm{V}}^{2}$. These results can be applied to information processing of the integration of wireless and fiber-optic networks in the classical regime or the quantum regime.