Electron-positron pair creation induced by multi-pulse train of electric fields: effect of randomness in time-delay

We investigate the creation of electron-positron pairs (EPPs) in a sequence of alternating-sign, time-dependent electric field pulse trains by solving the quantum Vlasov equations. Specifically, we focus on Sauter-like pulse trains with random time delays between successive pulses, drawn from a Gaussian distribution wherein the extent of fluctuations is controlled by the standard deviation σ_T of the distribution. We find that increasing σ_T leads to a dramatic transformation in the longitudinal momentum spectrum. The well-known fringe pattern, akin to that in the multi-slit interference, gets significantly modified. The averaged spectra exhibit a robust Gaussian-like envelope with residual oscillations, which are much more prominent in the central momentum region. Notably, we find that in certain cases, stochastic time delays lead to a pronounced enhancement in the central peak of the distribution function for pulse train containing N pulses. For example, for N=20 pulses, σ_T approx 31 \[m^-1\](about 17\% of the mean time delay) yields nearly a tenfold increase in the central peak, which for σ_T approx 50 \[m^-1\] (about 27\% of the mean time delay), scales up to 10³. This may open up new possibilities for optimizing multi-pulse field configurations and guide future experimental designs aimed at maximizing EPPs creation.