Seminarium Optyczne

The optical properties of atomic systems are shaped by their spatial symmetries, which are captured through multipolar transition moments. These values are tied to selection rules that determine which transitions can take place in a quantum system. In contrast, permanent multipolar moments are often brushed aside, assumed to cause only trivial energy shifts. This work explores light-matter interaction regimes where that assumption no longer holds. A paradigmatic quantum effect altered in polar systems is the familiar Rabi population transfer. When it takes place between eigenstates that carry permanent dipole moments, it leads to an additional oscillating dipole-one that radiates at the Rabi frequency [1,2]. This frequency can be controlled across a broad spectral range, which opens the door to all-optically tunable sources of coherent radiation [3,4]. Permanent dipole moments also change how light couples to matter. In non-polar systems, the interaction strength grows linearly with the amplitude of the electric field. But in polar systems under strong fields, this scaling can shift, pointing to a new regime of coherent dynamics, potentially resilient even in the presence of strong spatial variations in the driving field [5-7].[1] O. V. Kibis, G. Slepyan, S. A. Maksimenko, A. Hoffmann, Phys. Rev. Lett. 102, 023601 (2009).[2] G. Scala, K. Słowik, P. Facchi, S. Pascazio, F. V. Pepe, Phys. Rev. A 104, 013722 (2021).[3] I. Chestnov, V. A. Shahnazaryan, A. P. Alodjants, I. A. Shelykh, ACS Photonics 4, 2726-2737 (2017).[4] P. Gładysz, P. Wcisło, K. Słowik, Sci. Rep. 10, 17615 (2020).[5] P. Gładysz, K. Słowik, Phys. Rev. A 11 (5), 053704 (2025).[6] F. Pepe, K. Słowik, Phys. Rev. Lett. 133 (8), 083603 (2024).[7] N. Petkova, P. Gładysz, K. Słowik, Optics Letters 51.1 (2025): 57-60.[8] P. Gładysz, K. Słowik, F. Pepe, accepted in Phys. Rev. Research