Entanglement Entropy in Vacuum Pair Creation by Strong Fields

We investigate electron–positron pair production in single- and double-pulse Sauter-type electric fields, focusing on how temporal separation and field symmetry govern both momentum spectra and entanglement entropy. Using the quantum kinetic approach, we identify a universal three-stage evolution of the entanglement entropy: quasiparticle excitation, a transient oscillatory regime, and residual stabilization. Overlapping pulses produce broadened, irregular spectra with reduced final entropy, whereas well-separated pulses generate regular, high-contrast fringes and enhanced entanglement. This effect is particularly pronounced for antisymmetric configurations. We establish, for the first time, a quantitative link between momentum spectra and entropy: sharper, periodic spectral interference corresponds to stronger correlations between particle–antiparticle modes. Abstract Published by the Jagiellonian University 2025 authors