Resonant dipole-dipole interactions between Rydberg atoms and polar molecules at temperatures below 1 K

Abstract

Junwen Zou and Stephen Hogan Resonant dipole-dipole interactions between Rydberg helium atoms and cold ground-state ammonia molecules allow Förster resonance energy transfer between the electronic degrees of freedom in the atom, and the nuclear degrees of freedom associated with the inversion of the molecule [1,2]. In this talk I will describe recent experiments in which we have exploited the Stark effect in the triplet Rydberg states in helium, with values of the principal quantum number n between 38 and 40, to tune these interactions through resonance using electric fields below 10 V/cm. Resonance widths as narrow as 70 MHz have been observed in this work. These are indicative of mean centre-of-mass collision speeds on the order of 10 m/s, and collisions that occur at temperatures significantly below 1 K. Studies of Förster resonances in this collision system are of interest in the search for dipole-bound states [3] of Rydberg atoms or molecules and polar ground-state molecules, in the exploitation of long-range dipole-dipole interactions to regulate access to ion-molecule chemistry that can occur if the polar molecule penetrates inside the Rydberg electron charge distribution [4], and for coherent control and non-destructive detection [5,6]. [1] V. Zhelyazkova and S. D. Hogan, Phys. Rev. A 95, 042710 (2017) [2] K. Gawlas and S. D. Hogan, J. Phys. Chem. Lett. 11, 83 (2020) [3] S. M. Farooqi, D. Tong, S. Krishnan, J. Stanojevic, Y. P. Zhang, J. R. Ensher, A. S. Estrin, C. Boisseau, R. Côté, E. E. Eyler and P. L. Gould, Phys. Rev. Lett. 91, 183002 (2003). [4] V. Zhelyazkova, F. B. V. Martins, J. A. Agner, H. Schmutz and F. Merkt, Phys. Rev. Lett. 125, 263401 (2020) [5] E. Kuznetsova, S. T. Rittenhouse, H. R. Sadeghpour and S. F. Yelin, Phys. Chem. Chem. Phys. 13, 17115 (2011) [6] M. Zeppenfeld, Euro. Phys. Lett. 118, 13002 (2017)