Using 2D vortex plasmons/phonon polaritons to control electronic selection rules

Abstract

The discovery of orbital angular momentum (OAM) sustaining modes established a new degree of freedom by which to control not only the flow of light but also its interaction with matter. However, OAM sustaining modes have yet to be used to control the quantum dynamics of an electron in an atom or molecule due to the large length scale discrepancy between the wavelength of light and the size of the electron's orbital. In this work, we analyze the interaction between OAM carrying polariton vortex modes (for plasmon and phonon polaritons) and a hydrogen atom, and show that these modes can be used to engineer new selection rules in electronic transitions. Moreover, we show that these selection rules are robust to the displacement of the electronic system away from the vortex center. Perhaps more surprisingly, we find how displacement can be used favourably to tune which absorption process is dominant. Our findings are best suited to vortex modes that can be created in graphene, monolayer conductors, hBN, thin polar dielectrics, and many other polariton-sustaining thin materials. Another platform for observing these effects could be quantum dots interfaced with surface plasmons in-conventional metals.