E. O. Lazarev | Searcharxiv

arXiv2026

Bound-electron self-energy calculations in Feynman and Coulomb gauges: detailed analysis

The energy correction associated with the self-energy diagram is the leading (in magnitude) and fundamental (in significance) contribution to the Lamb shift in highly charged ions. Conventional approaches to this correction rely on partial-wave expansions, which is a stumbling block limiting accuracy. To elucidate the issue, we perform a comprehensive comparative analysis of partial-wave-expansion convergence between two gauges: Feynman and Coulomb. Some tricks for improving the convergence are discussed as well.

physics.atom-ph↗

arXiv2025

Generating entangled pairs of vortex photons via induced emission

Pairs of entangled vortex photons can promise new prospects of application in quantum computing and cryptography. We investigate the possibility of generating such states via two-level atom emission induced by a single photon wave packet with a definite total angular momentum (TAM). The entangled pair produced in this process possesses well-defined mean TAM with the TAM variation being much smaller than $\hbar$. On top of that, the variation exponentially decreases with the increase in TAM of the incident photon. Our model allows one to track the time evolution of the state of the entangled pair. An experimentally feasible scenario is assumed, in which the incident photon interacts with a spatially confined atomic target. We conclude that induced emission can be used as a source of entangled vortex photons with applications in atomic physics experiments, quantum optics, and quantum information sciences.

quant-ph↗