Probing a strongly interacting bose gas with ultralong-range Rydberg molecules

Ultralong-range Rydberg molecules (ULLRMs) are formed by the scattering between an excited Rydberg electron and at least one nearby neutral atom. Since the wave functions for ground state ULLRM dimers are strongly localized near the outer classical electron turning point, whose location depends on n, they can be used to probe pair correlation functions. In weakly interacting gases, the ULRRMs have been used to measure the pair correlations arising from quantum statistics on the length scale of the thermal de Broglie wavelength [1]. In the strongly interacting regime, however, ULRRMs can be used to probe the two-particle scattering wavefunction at short range. I will present measurements of the excitation rate of the ULRRM dimers in a strongly interacting gas of ⁸⁶Sr atoms (a_s = 823 a₀). In particular, we have observed contributions from s-wave and d-wave components of the scattering wavefunction to the formation of ULRRMs. The dependence of each components on an external magnetic field and the momentum kicks imparted by the excitation photons are also studied.

[1] J. D. Whalen, et al. Probing nonlocal spatial correlations in quantum gases with ultra-long-range Rydberg molecules, Phys. Rev. A 100, 011402 (2019)