Spirals, vortices, and helicity entanglements in dynamical Sauter-Schwinger pair creation

We study helicity correlations of electron-positron pairs created by a homogeneous time-dependent electric field in the Sauter-Schwinger scenario. Our analysis is based on solving the Dirac equation with the Feynman or anti-Feynman boundary conditions, which is equivalent to the scattering matrix approach widely used in high energy physics. Most importantly, both these methods allow to fully account for the helicity (or, more generally, spin) correlations of created particles. The influence of helicity correlations and the carrier-envelope phase of the electric pulse on the properties of topological structures (such as spirals and vortices) in momentum distributions of created particles is investigated. The generation of maximally entangled helicity states is discussed and the possibility of using a short electric pulse as a fast switch between them is indicated.