Quantum radiation at finite temperature

We investigate the phenomenon of quantum radiation - i.e. the conversion of (virtual) quantum fluctuations into (real) particles induced by dynamical external conditions - for an initial thermal equilibrium state. For a resonantly vibrating cavity a rather strong enhancement of the number of generated particles (the dynamical Casimir effect) at finite temperatures is observed. Furthermore we derive the temperature corrections to the energy radiated by a single moving mirror and an oscillating bubble within a dielectric medium as well as the number of created particles within the Friedmann-Robertson-Walker universe. Possible implications and the relevance for experimental tests are addressed. PACS: 42.50.Lc, 03.70.+k, 11.10.Ef, 11.10.Wx.