  We predict dominating cooperative two-photon emission from two quantum dots
coupled with a single mode photonic crystal cavity. The cooperative two photon
emission occurs when excitons in two off-resonantly coupled quantum dots decay
simultaneously. The interaction with common cavity field leads to cavity
induced two-photon emission which is strongly inhibited by electron phonon
coupling. The interaction with common phonon bath produces phonon induced
two-photon emission which increases on increasing temperature. For identical
quantum dots cavity induced two-photon emission is negligible but phonon
induced two-photon emission could be large.
