We analyze the nonadiabatic effects on the propagation of a two-mode squeezed field inside a medium of three-level $\Lambda$ atoms that display the dark resonance. We identify the different effects for the two-mode quantum properties: (i) unconditional transparency for the sum squeezing and (ii) induced transparency or spectral narrowing for the difference squeezing depending on the relative widths of the initial correlation spectrum to the transparency window. These effects combine to induce transparency or spectrum narrowing for the bipartite entanglement. The potential applications range from quantum information to laser spectroscopy and frequency standards.

• Received 10 February 2011

DOI:https://doi.org/10.1103/PhysRevA.83.053842