Towards making KRb - Rb* triatomic ultra-long-range Rydberg molecules

Ultra-long range Rydberg molecules offer large permanent electric dipole moments, on the order of kilo-Debyes, providing a new platform to study quantum physics and chemistry such as quantum sensing, many-body quantum systems, and controlled cold chemical interactions.

Diatomic Rydberg molecules formed through the scattering of the Rydberg electron on a second atom have previously been demonstrated experimentally in dense Rb and Cs gasses [1,2]. Triatomic ultra-long-range Rydberg molecules are predicted to form between a Rydberg atom and a diatomic polar molecule via the Rydberg electron–molecule anisotropic dipole interaction [3] but have not been experimentally demonstrated yet. In our experiment, we prepare a mixture of KRb molecules in a rotationally excited state and Rb atoms in their electronic ground state. In such a system, long range Rydberg molecules are predicted to form by applying a laser pulse whose frequency is red-detuned from the two-photon excitation to the desired Rydberg state. Here, we present our recent spectroscopic data searching for these triatomic Rydberg molecules.

[1]: Bendkowsky, V., Butscher, B., Nipper, J. et al. Observation of ultralong-range Rydberg molecules. Nature 458, 1005–1008 (2009). https://doi.org/10.1038/nature07945

[2]: Shaffer, J.P., Rittenhouse, S.T. & Sadeghpour, H.R. Ultracold Rydberg molecules. Nat Commun 9, 1965 (2018). https://doi.org/10.1038/s41467-018-04135-6

[3]: Rosario González-Férez et al 2020 J. Phys. B: At. Mol. Opt. Phys. 53 074002