Structured relativistic electron and neutron vortex beams in intense laser fields

In this talk, I will discuss how the spin and OAM degrees of freedom give rise to an intrinsic spin-orbit coupling (also called spin-to-orbit conversion) in structured relativistic quantum waves. The main focus of my talk will be on the interaction of such twisted, both charged and neutral, matter waves with intense laser pulses. In order to demonstrate the possibility of controlling of vortex beams both in the transverse direction and in the temporal domain, we develop an exact relativistic quantum theory by constructing two new sets of solutions to generalized Dirac equations, accounting for the interaction of electrons and neutrons with external electromagnetic fields. In more details, using the fundamental superposition principle of (linear) relativistic quantum electrodynamics, we superimpose a multitude of plane-wave charged (Volkov) or neutral (Skobelev) states over a mono-energetic cone representing a twisted Bessel state. We show that the laser field gives rise to a Lorentz-induced shift of the vortex core of twisted electrons, the transverse profile of which maintains its overall shape throughout the propagation in a pulse. In contrast, while the vortex core of twisted neutrons remains unaffected, the spin- and OAM-dependent profile experiences an inhomogeneous distribution due to the interaction of neutron's anomalous magnetic moment with the magnetic field of the laser.

Our new, Bessel-type solutions may be employed in many fields of physics, from atomic and subatomic physics to topological condensed matter theory, and can be useful for evaluating matrix elements for various laser-assisted scattering processes, especially, at high intensities.