Direction-dependent coupling between a nanofiber-guided light field and a two-level atom with an electric quadrupole transition

Abstract

We study the directional dependence of the coupling between a nanofiber-guided light field and a two-level atom with an electric quadrupole transition. We examine the situation where the atom lies on the fiber transverse axis $x$, the quantization axis for the atomic internal states is the other orthogonal transverse axis $y$, the atomic upper and lower levels are the magnetic sublevels $M^{\prime }$ and $M$ of hyperfine-structure levels of an alkali-metal atom, and the field is in a quasilinearly polarized fundamental guided mode HE${}_{11}$ with the polarization $\xi =x$ or $y$. We find that the absolute value of the quadrupole Rabi frequency depends on the propagation direction of the light field in the cases of ($M^{\prime }-M=\pm 1$, $\xi =y$) and ($M^{\prime }-M=\pm 2$, $\xi =x$). We show that the directional dependence of the coupling leads to the directional dependence of spontaneous emission into guided modes. We find that the directional dependence of the atom-field coupling in the case of quadrupole transitions is not entirely due to spin-orbit coupling of light: there are some other contributions resulting from the gradient of the spatial phase factor of the field.

arXiv admin note: text overlap with arXiv:2205.12440

References in corpus (6)

• Chiral Quantum Optics
• Chiral nanophotonic waveguide interface based on spin-orbit coupling of light
• Angular Momentum Transfer in Interaction of Laguerre-Gaussian Beams with Atoms and Molecules
• Anisotropy in scattering of light from an atom into the guided modes of a nanofiber
• Enhancement of the quadrupole interaction of an atom with guided light of an ultrathin optical fiber
• Channeling of spontaneous emission from an atom into the fundamental and higher-order modes of a vacuum-clad ultrathin optical fiber

Cited by in corpus (1)

• Polarization transport in optical fibers beyond Rytov's law