Vacuum pair production under spatially asymmetric time-oscillating electric fields

Abstract: We investigate electron-positron pair production from the quantum vacuum in spatially asymmetric, time-oscillating electric fields using the Dirac-Heisenberg-Wigner (DHW) formalism. The field configuration combines spatially separated Sauter-type pulses with temporal oscillations, including frequency chirps and phase modulation. Our results demonstrate that spatial asymmetry significantly enhances pair production compared to symmetric fields, while optimal tuning of temporal parameters (e.g., frequency $\omega$ and chirp $b$) further amplifies the yield. For $\omega \gtrsim 0.4m$, multiphoton-dominated processes generate oscillatory momentum spectra, whereas low-frequency fields ($\omega \lesssim 0.3m$) exhibit tunneling-dominated Gaussian distributions. Chirped fields induce spectral asymmetry and interference patterns, with peak yields increasing by up to a factor of 9 for $\omega = 0.7m$ and $b = 0.5\omega/\tau$. These findings provide a pathway to optimize pair production in experimentally feasible spatiotemporal field configurations.