Optical nanofibers – very thin, tapered optical fibers where the waist diameter is less than the propagating light wavelength – have been shown to be very useful tools for atom-light interactions. Their small size and relative ease of integration into optical fiber-based experimental setups, in addition to their minimal perturbation on magneto-optically trapped cold atoms, have ensured their adoption into cold atom physics. Here, we will discuss some recent applications of optical nanofibers to manipulate, trap, and control cold 87Rb atoms in ground or Rydberg states. We will present some recent experimental and theoretical results related to the interactions between the atoms and the optical nanofiber field and introduce some of the limitations observed.
In contrast to paraxial waves, strongly confined light can carry significant transverse spin angular momentum. Here we
report on its direct detection in the evanescent electromagnetic field near the ultrathin waist of an optical nanofiber
waveguide. We demonstrate the spin by its contribution to rotation of an anisotropic microsphere held and spun near the
nanofiber waist by optical tweezers. By setting the driving spin angular momentum in the optical tweezers to be parallel
or antiparallel with respect to the transverse spin near the nanofiber, we can speed up or slow down the particle’s rotation
by about a half of the rotation rate observed without the light in the fiber. We also explore the dependence of this
optomechanical effect on the propagation direction and polarization of the guided light.