Radiation signal accompanying the Schwinger effect

The properties of the forced oscillations of virtual electron-positron plasma generated in vacuum under the action of a short laser pulse are considered. By 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 electron-positron creation from vacuum.

Figure 1

(a) Distribution function $f(\mathbf{p},t)$ at $\mathbf{p}=0$ and (b) pair density (5) as functions of time together with the square of the external field strength $E\left(t\right)$. The field parameters are $E_0=0.1E_{\text{c}}$, $\mathrm{\Omega }=0.1m$, and $\sigma =12$. The curve $E^2\left(t\right)$ almost exactly reproduces the other two curves.

Figure 2

Temporal dependence of (a) the conduction current and (b) the polarization current together with the external field strength $E\left(t\right)$. The field parameters are $E_0=0.1E_{\text{c}}$, $\mathrm{\Omega }=0.1m$, and $\sigma =12$.

Figure 3

Spectrum of (a) the conduction and polarization currents and (b) the external field $E\left(t\right)$. The field parameters are $E_0=0.1E_{\text{c}}$, $\mathrm{\Omega }=0.1m$, and $\sigma =12$.

Figure 4

(a) Spectral energy density (13) of the VEPP oscillations for $E_0=0.05E_{\text{c}}$, $0.1E_{\text{c}}$, $0.2E_{\text{c}}$, and $0.3E_{\text{c}}$ and (b) the relative brightness $B_1$ and $B_3$ defined in Eq. (14) as a function of $E_0$ according to the data. The other field parameters are $\mathrm{\Omega }=0.1m$ and $\sigma =12$.