Abstract
An analytical description of a three-level atom in an optical cavity coupled to the environment is obtained. The Husimi function and the Wehrl density are calculated to investigate the information loss dynamics of the phase space. The Wehrl entropy and the atomic information entropy are explored to study the coherence loss of the three-level system. We show that these measures, as non-classical indicators, are very sensitive not only to the coupling strength to the reservoir but also to the initial state.