Many-particle effects in the propagation of slow light through atomic gases

Quantum interference effects in atoms, such as electromagnetically induced transparency in three-level atoms in Lambda-configuration, can be used to control light and can be utilized for quantum information processing and communication. We present a novel theoretical treatment of the interaction of light with an ensemble of Lambda-atoms that includes many-body effects in atomic gases of high density. In this regime atom-atom correlations are generated by resonant dipole-dipole interactions (DDI), which lead to modifications of the linear and nonlinear optical properties of the medium. We use many-body Green's functions to analyze the impact of DDI on electromagnetically induced transparency and derive the susceptibility of the atomic gas. Our method combines the dressed-state approach to coherent population trapping with Keldysh diagram technique of non-equilibrium many-body theory. The developed method provides an intuitive picture of the evolution process of light passing through this system and may help to optimize quantum control of light in atomic gases.