Twisted Light - Theory and Applications

Light beams with helical phase fronts, that also carry a nonzero projection of the orbital angular momentum (OAM) upon their propagation direction, are currently of considerable interest in many areas of modern physics.

Having a complex polarization patterns and highly inhomogeneous intensity profiles with a central dark spot, these twisted (or vortex) beams have proven to be a valuable tool in classical and quantum information transfer, super-resolution optical sensing, as well as in manipulation of nanoparticles and even Bose Einstein condensates.

During the recent years, moreover, a special attention in experiment and theory has been paid to the coupling of twisted light modes with single trapped ions. It was shown that twisted light can be efficiently employed to induce dipole-forbidden atomic transitions while suppressing the AC Stark shift of their frequencies.

In order to illustrate these atomic-physics applications of OAM modes, I will discuss recent studies on laser-induced electric octupole (E3) transition in Yb+ ion. This transition is discussed as a candidates for novel frequency standard, and, thus, the use of twisted light may help in development of new generation of atomic clocks.