Abstract

The study on the interaction between electromagnetic fields and multi-level atoms or molecules has discovered many interesting effects including elcctromagnetically induced transparency (EIT),^1,2 enhanced dispersion with reduced absorption,^3,4 and lasing without inversion.⁵ Recent interests include ultraslow group velocity of light, and superluminal light propagation.⁶ Atomic coherence created between different atomic levels plays an essential rule in these experiments. On the other hand, quantum features in the interaction between electromagnetic fields and three-level systems based on atomic coherence have attracted extensive theoretical interests. These include generation of amplitude- squeezed and quantum noise-correlated states of light with EIT,⁷ entanglement of atomic states with light fields,⁸ and quantum memory for light.⁹ According to these theoretical works, manipulation of quantum states of either light fields or atoms via atomic coherence is possible.

© 2001 Optical Society of America