arXiv subjects

Shaohu Lei

Publications and source records attributed to Shaohu Lei.

4 recordsLinked to original sources

arXiv2024

Generation of Quantum Vortex Electrons with Intense Laser Pulses

Accelerating a free electron to high energy forms the basis for studying particle and nuclear physics. Here it is shown that wavefunction of such an energetic electron can be further manipulated with femtosecond intense lasers. During the scattering between a high-energy electron and a strong laser pulse, we find a regime where the enormous photon spin angular momenta can be efficiently transferred to the electron orbital angular momentum (OAM). The wavefunction of the scattered electron is twisted from its initial plane-wave state to quantum vortex state. Nonlinear quantum electrodynamics (QED) theory suggests that GeV-level electrons acquire average intrinsic OAM beyond 100 h-barat laser intensities of 10^20W/cm^2 with linear scaling. These electrons emit gamma photons with double-peaked spectrum, which sets them apart from ordinary electrons. The findings demonstrate a proficient method for generating relativistic leptons with quantum vortex wavefunctions based on existing laser technology, thereby fostering a novel source for particle and nuclear physics.

physics.optics↗

arXiv2023

Transfer of spin to orbital angular momentum in the Bethe-Heitler process

According to the conservation of angular momentum, when a plane-wave polarized photon splits into a pair of electron-positron under the influence of the Coulomb field, the spin angular momentum (SAM) of the photon is converted into the angular momentum of the leptons. We investigate this process (the Bethe-Heitler process) by describing the final electron and positron with twisted states and find that the SAM of the incident photon is not only converted into SAM of the produced pair, but also into their orbital angular momentum (OAM), which has not been considered previously. The average OAM gained by the leptons surpasses the average SAM, while their orientations coincide. Both properties depend on the energy and open angle of the emitted leptons. The demonstrated spin-orbit transfer shown in the Bethe-Heitler process may exist in a large group of QED scattering processes.

hep-ph↗

arXiv2021

Generation of relativistic positrons carrying intrinsic orbital angular momentum

High energy positrons can be efficiently created through high-energy photons splitting into electron-positron pairs under the influence of the Coulomb field. Here we show that a new degree of freedom-the intrinsic orbital angular momentum (OAM) can be introduced into relativistic positrons when the incident photons are twisted. We developed the full-twisted scattering theory to describe the transfer of angular momentum before and after the interaction. It is found that the total angular momentum (TAM) of the photon is equally distributed among the positron and electron. For each photon TAM value, the generated leptons gain higher average OAM number when the photon spin is anti-parallel to its TAM. The impact of photon polarization on the OAM spectrum profile and the scattering probability is more significant at small photon TAM numbers, owing to the various interaction channels influenced by flipping the photon spin. Our work provides the theoretical basis to study OAM physics in particle scattering and to obtain copious relativistic vortex positrons through the Beth-Heitler process.

hep-ph↗

arXiv2021

Vortex Breit-Wheeler Electron-positron pair creation via vortex gamma-photons

Particles in quantum vortex states (QVS) carrying definite orbital angular momenta (OAM) brings new perspectives in various fundamental interaction processes. When unique properties arise in the QVS, understanding how OAM manifest itself between initial particles and the outcome in vortex particle collisions becomes essential. This is made possible by applying the complete vortex description for all involved particles such that angular momenta (AM) are represented by explicit quantum numbers and their connections are naturally retrieved. We demonstrate the full-vortex quantum-electrodynamics (QED) results for the Breit-Wheeler pair creation process and derive the AM-dependent selection rule. The numerically resolved cross-sections show anti-symmetric spin polarization and most importantly, the first OAM spectra in vortex collision processes. The latter reveals efficient conversion of OAM to created pairs, leading to featured hollow and ring-shaped structure in the density distribution. These results demonstrate a clear picture in understanding the OAM physics in the scattering processes of high energy particles.

hep-ph↗