Transfer of angular momentum of guided light to an atom with an electric quadrupole transition near an optical nanofiber

We study the transfer of angular momentum guided photons to a two-level atom with an electric quadrupole transition near optical nanofiber. show that generation axial orbital torque driving field on is governed by internal-state selection rules for and conservation law photon given in Minkowski formulation. find depends momentum, change atomic internal state, quadrupole-transition Rabi frequency. calculate numerically torques transitions between sublevel $M=2$ hyperfine-structure level $5{S}_{1/2}F=2$ sublevels ${M}^{\ensuremath{'}}=0$, 1, 2, 3, 4 $4{D}_{5/2}{F}^{\ensuremath{'}}=4$ $^{87}\mathrm{Rb}$ atom. absolute value higher-order mode ${\mathrm{HE}}_{21}$ larger than fundamental ${\mathrm{HE}}_{11}$ except case ${M}^{\ensuremath{'}}\ensuremath{-}M=2$, where vanishing.