Vortex structures in electron-positron pair production by two-colored fields

TL;DR

This paper explores the topological vortex structures in electron-positron pairs generated by two-colored electromagnetic fields, revealing dynamic transitions and spin-dependent momentum-space geometries governed by angular momentum conservation.

Contribution

It uncovers the formation of vortex lattices and their spin-dependent morphologies in vacuum pair production under time-delayed two-color fields, highlighting new topological phenomena.

Findings

Vortex lattice structures emerge at specific time delays.

Spin configurations dictate distinct momentum-space geometries.

Vortex coherence dissolves at large delays, but spin geometries persist.

Abstract

We investigate the spin resolved vortex properties of electron positron pairs created from vacuum in time delayed, two color electromagnetic fields. By treating the temporal delay G as a continuous tuning parameter, we reveal a dynamic transition from interference-dominated domain patterns at G=0 to the nucleation of quantized vortex lattices at G=0.5. These topological structures exhibit a staggered arrangement analogous to von Karman vortex streets in fluid dynamics. We demonstrate that the momentum-space morphology is strictly governed by spin orbit selection rules, i.e., parallel spin configurations enforce a dipole-like connectivity, while anti-parallel configurations resolve into distinct quadrupole structures. This difference originates from the conservation of total angular momentum Jz, where the spin projection determines the required orbital angular momentum Lz of the created pairs. At large delays (G greater than 1), macroscopic vortex coherence dissolves into a chaotic phase landscope due to multi-channel interference, yet the spin-dependent nodal geometries remain robust. Our findings suggest that these topological signatures provide a high-fidelity diagnostic for the quantum dynamics of vacuum excitations in strong field QED.