Excitation of high orbital angular momentum Rydberg states with Laguerre-Gauss beams

TL;DR

This paper explores how Laguerre-Gauss laser beams with orbital angular momentum can excite high angular momentum Rydberg states in atoms, surpassing traditional selection rules, with implications for atomic physics and quantum control.

Contribution

It demonstrates the transfer of orbital angular momentum from Laguerre-Gauss beams to atomic internal states, enabling access to higher angular momentum Rydberg states via single-photon excitation.

Findings

Orbital angular momentum can be transferred to atomic states, violating standard dipolar selection rules.

The spatial structure of Laguerre-Gauss beams influences radial coupling strength.

Theoretical generalization includes effects of fine and hyperfine splitting.

Abstract

We consider the excitation of Rydberg states through photons carrying an intrinsic orbital angular momentum degree of freedom. Laguerre-Gauss modes, with a helical wave-front structure, correspond to such a set of laser beams, which carry some units of orbital angular momentum in their propagation direction. We demonstrate that, in a proper geometrical setting, this orbital angular momentum can be transferred to the internal degrees of freedom of the atoms, thus violating the standard dipolar selection rules. Higher orbital angular momentum states become accessible through a single photon excitation process. We investigate how the spacial structure of the Laguerre-Gauss beam affects the radial coupling strength, assuming the simplest case of hydrogen-like wavefunctions. Finally we discuss a generalization of the angular momentum coupling, in order to include the effects of the fine and hyperfine splitting, in the context of the Wigner-Eckart theorem.