Enhanced quadrupole effects for atoms in optical lattices

Nimrod Moiseyev, Milan Šindelka, Lorenz S. Cederbaum

S. Al‐Awfi

V. E. Lembessis, M. Babiker

We show that the normally weak optical quadrupole interaction in atoms is enhanced significantly when the atom interacts at near resonance with an optical vortex. In particular, the forces and torque acting on the atom are shown here to scale up with the square of the winding number l of the vortex. Because the integer l can be arranged to be large, this property allows for processes involving dipole-forbidden, but quadrupole-allowed, transitions in atoms, such as cesium and oxygen, to come into play. We show that the mechanical effects of vortex light on atoms involving translational and rotational motion as well as trapping should be significantly enhanced for quadrupole transitions and present novel features with useful implications for the emerging field of atomtronics.

А. В. Тайченачев, Valeriy I. Yudin, Vitalii D Ovsiannikov +2 more

We report a hitherto undiscovered frequency shift for forbidden J = 0-->J = 0 clock transitions excited in atoms confined to an optical lattice. These shifts result from magnetic-dipole and electric-quadrupole transitions, which have a spatial dependence in an optical lattice that differs from that of the stronger electric-dipole transitions. In combination with the residual translational motion of atoms in an optical lattice, this spatial mismatch leads to a frequency shift via differential energy level spacing in the lattice wells for ground state and excited state atoms. We estimate that this effect could lead to fractional frequency shifts as large as 10(-16), which might prevent lattice-based optical clocks from reaching their predicted performance levels. Moreover, these effects could shift the magic wavelength in lattice clocks in three dimensions by as much as 100 MHz, depending on the lattice configuration.

Georg A. Raithel, G. Birkl, William D. Phillips +1 more

S. Al‐Awfi

Recently, some physical research has recognized the coupling of optical phase singularity light with quadrupole-active atomic transitions. We show that a Laguerre-Gaussian beam, when completely internally reflected at the dielectric/vacuum interface, can generate a well-defined surface spiral beam with a two-dimensional intensity distribution confined to a sub-wavelength region near the interface outside of the dielectric. The quadrupole interaction has been shown to be significantly enhanced in the case of coating the planar surface of a dielectric prism using multilayer dielectric thin films of different thicknesses. The mechanical action on the atom due to the optical forces characterized by optical quadrupole transitions could greatly facilitate the revolution of optical manipulation of neutral atoms along the dielectric/vacuum interface. The typical optical quadrupole potential, evaluated for the atomic transition, corresponds to λ=675.0nm with ΓQ=7.8×105s-1, in Cesium atoms, which is a dipole-forbidden but quadrupole-allowed transition. The parameters used to compute the optical quadrupole potential are similar to those in recent experiments. The factors controlling the general enhancement are pointed out and discussed.