  The properties of the forced oscillations of electron-positron plasma (EPP)
generated from vacuum under the action of a short laser pulse are considered.
Calculating the density of the conduction and polarization currents within the
quantum kinetic approach, we demonstrate the presence of plasma oscillations at
the frequency of the external field and its odd harmonics. It is expected that
radiation generated by these plasma oscillations can be observed outside the
interaction region, for example, outside the focal spot of two
counterpropagating laser beams, and can serve as an indicator of the Schwinger
mechanism of the EPP creation from vacuum.
