Electromagnetically Induced Transparency with Squeezed Vacuum

The squeezed vacuum resonant on the ${}^{87}\mathrm{Rb}$ $D_1$ line (probe light) was injected into an optically dense rubidium gas cell with a coherent light (control light). The output probe light maintained its quadrature squeezing within the transparency window caused by the electromagnetically induced transparency (EIT). The results reported here are the first realization of EIT in the full quantum regime.