SAMOP 2023 – scientific programme

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A: Fachverband Atomphysik

A 10: Atomic Systems in External Fields

A 10.1: Invited Talk

Tuesday, March 7, 2023, 11:00–11:30, F107

Interaction of twisted light with a trapped atom: Interplay of electronic and motional degrees of freedom — •Anton Peshkov^1,2, Yuriy Bidasyuk¹, Richard Lange¹, Tanja Mehlstäubler^1,3, Nils Huntemann¹, Ekkehard Peik¹, and Andrey Surzhykov^1,2 — ¹Physikalisch-Technische Bundesanstalt — ²Technische Universität Braunschweig — ³Leibniz Universität Hannover

Twisted light modes with orbital angular momentum (OAM) show great promise for applications in atomic clocks since excitation of a trapped atom in their low-intensity center can result in significant suppression of an undesirable light shift. In such experiments, however, an accurate description of induced Rabi oscillations is complicated by the transverse atomic motion within the strongly inhomogeneous optical field of twisted light. Here, we present a theoretical model to describe the time evolution of a single atom in a twisted Laguerre-Gaussian beam, taking into account vibrational states of the atom’s center-of-mass motion in a harmonic potential created by a trap. Calculations have been performed for the 4s_1/2 → 3d_5/2 electric quadrupole (E2) transition in Ca⁺ ion. An analysis based on the density matrix formalism and the Liouville-von Neumann equation shows that the atom may undergo unconventional anharmonic Rabi oscillations that are attributed to the strong coupling between vibrational levels. This effect is accompanied by the angular momentum transfer from twisted light to the atomic center-of-mass motion and becomes most pronounced when the Rabi frequency is comparable to the trapping one.