We report characterization of EIT resonances in the D1 line of Rb 87 under various experimental conditions. The dependence of the EIT linewidth on the power of the control field investigated. Strictly linear behavior between the ground levels as the main source of decoherence. We therefore formulated a new theory assuming pure dephasing to be the main decoherence mechanism. We also performed experiments where we created additional decoherence mechanisms by means of a counter-propagating repumper field. This field caused the ground-state population exchange, thus reproducing conditions in which the original theory is valid.
We demonstrate a quantum communication protocol that enables frequency conversion of quantum optical information in an adiabatic way. The protocol is based on electromagnetically induced transparency in sustems with multiple excited levels. The proof-of-principle experiment is performed using the hyperfine levels of the rubidium D1 line.
We present an experimental study of decoherence of the ground energy levels of <sup>87</sup>Rb atoms in vapor cells. We measure the decoherence of the ground state using three different methods: measuring the decay constant of the storage of light in atomic vapor, the decay rates of transient coherence oscillations of the ground state, and the width of the electromagnetically induced transparency resonances. The measurements showed decoherence rates on the scale of 10<sup>4</sup> s<sup>-1</sup>.