Rapidity-Coupled Spin Dynamics in Pulsed Laser Fields from Physics-Informed Neural Networks

Abstract:Carrier-envelope-phase (CEP) stabilized few-cycle pulses make the sub-cycle field structure a control parameter for laser-driven polarized electron sources, yet spin solvers for such pulses are rarely tested against exact results. We show that for an electron initially at rest in a linearly polarized plane-wave pulse the rest-frame polarization angle follows the instantaneous vector potential, $\Sigma = 2\arctan(a_x/2) + a_e a_x$ with $a_e$ the electron anomaly: the net rotation vanishes for every CEP, while the peak intra-pulse angle varies over the CEP by 3.02 degrees for a two-cycle and by 0.22 degrees for an eight-cycle pulse. The result follows from the Volkov orbit in longitudinal and transverse rapidities. We use it to validate a light-front reference integrator and a physics-informed neural network trained only on the light-front equations, which reaches $4\times10^{-5}$ in the spin sector and carries over to elliptical polarization, for which no closed-form solution is known. This gives validated tools for CEP-resolved spin dynamics in intense fields.

14 pages, 3 figures; Letter followed by Supplemental Material. Submitted to Physical Review A. Code and data: this https URL

Optics (physics.optics); Plasma Physics (physics.plasm-ph); Quantum Physics (quant-ph)

arXiv:2609.19756 [physics.optics]

(or arXiv:2609.19756v1 [physics.optics] for this version)

https://doi.org/10.48550/arXiv.2609.19756 Focus to learn more arXiv-issued DOI via DataCite (pending registration)

arXivLabs is a framework that allows collaborators to develop and share new arXiv features directly on our website.

Both individuals and organizations that work with arXivLabs have embraced and accepted our values of openness, community, excellence, and user data privacy. arXiv is committed to these values and only works with partners that adhere to them.

Have an idea for a project that will add value for arXiv's community? Learn more about arXivLabs.