Interaction of twisted light with individual atoms and atomic ensembles

• Applicant: Professor Dr. Andrey Surzhykov
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 445408588

In recent years, a considerable interest has been given to the application of twisted light beams in atomic physics. In contrast to conventional plane-wave radiation, these beams are designed to carry a nonzero projection of the orbital angular momentum (OAM) upon their propagation direction. Nowadays, the twisted photons with their helical phase fronts, annular intensity profiles, and complex energy flow patterns can be routinely generated at a wide range of wavelengths from radio frequencies to x-ray energies. These beams can serve as a valuable tool to better understand how the OAM influences the coupling between radiation and matter. In this work we plan to investigate the interaction of twisted light both with single trapped atoms (or ions) as well as with atomic and molecular ensembles. For the single-atom scenario, special attention will be paid to the bound-state transitions whose selection rules and probabilities can be efficiently modified by the OAM of photons. The coupling to the twisted light, moreover, will allow us to reduce the light (Stark) shift of atomic states. This reduction is of great importance for operating dipole-forbidden atomic clock transitions. We also propose to investigate the enhancement of non-dipole effects in atomic ionization by twisted light for the photon energies near the Cooper minimum, with an emphasis on understanding the angular distribution and/or polarization of photoelectrons. Moreover, we intend to analyze the photoionization of molecules of different symmetries by twisted radiation. For the interaction of twisted light with atomic ensembles, we will focus in particular on the Hanle effect in atomic vapors. Apart from the twisted photons, we plan to consider the twisted electron beams for which we shall develop the Williams-Weizsaecker method enabling us to describe the bremsstrahlung of electrons in the field of the ions.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Science Foundation
• Cooperation Partners: Professor Dr. Alexei N. Grum-Grzhimailo, Ph.D.; Dr. Dmitry Karlovets; Professor Dr. Valeriy Serbo