2025/09/01 by Schmidt, R. P., Martin-Domene, S., Peshkov, A. A. +2
#Atomic Physics (physics.atom-ph) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2509.01561
Electric and magnetic fields are inherently coupled in an electromagnetic wave. However, structured light beams enable their spatial separation. In particular, azimuthally polarized laser beams exhibit a localized magnetic field on-axis without the electric counterpart. Recent study by Martin-Domene et al. [App. Phys. Lett. 124, 211101 (2024)] has shown that combining these beams enables the generation of locally isolated magnetic fields with a controllable direction and phase. In the present paper we propose a method to probe and characterize such magnetic fields by studying their interaction with a single trapped atom. In order to theoretically investigate magnetic sublevel populations and their dependence on the relative orientation and phase -- i.e. the polarization state -- of the isolated magnetic field, we use a time-dependent density-matrix method based on the Liouville-von Neumann equation. As illustrative cases, we consider the 2s2 2p2 3P0 - 2s2 2p2 3P1, the 1s2 2s2 1S0 - 1s2 2s 2p 3P2, and the 2 s2 2p 2 P1/2 - 2 s2 2p 2 P3/2 transitions in 40Ca14+, 10Be, and 38Ar13+, respectively. Our results indicate that monitoring atomic populations serves as an effective tool for probing isolated vector magnetic fields, which opens avenues for studying laser-induced processes in atomic systems where electric field suppression is critical.