  We propose a trap for cold neutral atoms using a fictitious magnetic field
induced by a nanofiber-guided light field. In close analogy to magnetic
side-guide wire traps realized with current-carrying wires, a trapping
potential can be formed when applying a homogeneous magnetic bias field
perpendicular to the fiber axis. We discuss this scheme in detail for
laser-cooled cesium atoms and find trap depths and trap frequencies comparable
to the two-color nanofiber-based trapping scheme but with one order of
magnitude lower powers of the trapping laser field. Moreover, the proposed
scheme allows one to bring the atoms closer to the nanofiber surface, thereby
enabling efficient optical interfacing of the atoms with additional light
fields. Specifically, optical depths per atom, $\sigma_0/A_{\rm eff}$, of more
than 0.4 are predicted, making this system eligible for nanofiber-based
nonlinear and quantum optics experiments.
