Pair creation via Amplitude-Modulated Periodic and Quasiperiodic Pulse Sequences

Original Abstract

We study nonperturbative pair production driven by alternating-sign electric field pulse trains. Using a quantum kinetic approach, we analyze both the longitudinal momentum spectrum and the particle yield for pulse sequences with either strictly periodic temporal structure, in which the pulse amplitudes alternate in a regular and repeating (E_1, E_2) pattern, or quasiperiodic (Fibonacci-ordered) structure, where the amplitudes follow a deterministic but aperiodic sequence generated by the Fibonacci substitution rule, exhibiting long-range order without exact repetition. For N=12 pulses, periodic trains generate regularly modulated spectra characteristic of multi-slit (Ramsey-type) interference, whereas Fibonacci sequences produce fragmented structures and partial momentum-space localization. Increasing the pulse number to N=20 further enhances these effects: periodic driving yields sharper and higher-contrast interference fringes, while quasiperiodic ordering leads to stronger localization and increasingly irregular spectral features.The particle yield exhibits a strongly nonlinear dependence on the field-strength ratio. For weak modulation , both temporal orderings produce nearly identical yields. For stronger fields, a modest crossover behavior is observed, with quasiperiodic sequences yielding slightly larger values than the periodic case. Overall, temporal ordering primarily redistributes spectral weight in momentum space, while the integrated yield is governed predominantly by the effective field strength. These results establish long-range temporal ordering as an effective control parameter in multipulse Schwinger pair production and provide guidance for designing tailored pulse sequences in future high-intensity laser experiments.