Electromagnetic radiation in a cavity with a time-dependent mirror

The quantum radiation field inside a double cavity is examined. The double cavity consists of a cavity containing a reflecting mirror. Two independent radiation fields are present inside the cavity. It is then assumed that th e mirror becomes suddenly transparent. The double cavity transforms thus in to a single cavity. The relationship between the radiation fields before an d after the change is investigated. It is shown that the sudden change exci tes the radiation modes of the single cavity. Only modes having a node at t he position of the mirror are not excited. The sudden change of the mirror' s reflectivity can thus generate photons from the vacuum. It is also shown that the sudden change produces squeezing. These features of the double cav ity are then employed in a gedankenexperiment for the generation of entangl ement between noninteracting atoms with the quantum eraser technique. [S105 0-2947(99)07007-9].