Measurement of g⁽³⁾(R) in quantum gases using ultralong range Rydberg molecules(ULRMs)

ULRMs have been used as an in-situ probe to measure the non-local spatial correlations in quantum gases¹, where the Rydberg dimer excitation rates directly measure the pair correlation function g⁽²⁾(R).  Different internuclear separations, R, are probed by changing the principal quantum number n. We extend this study to measure excitation rates of Rydberg trimers in ultracold gases of strontium to extract the non-local three-body correlation function g⁽³⁾(R) and present evidence of bunching that agrees with theoretical predictions of the third-order correlation function. We also discuss progress towards understanding excitation of Rydberg dimers and trimers in a Bose-Einstein condensate of ⁸⁴Sr to demonstrate long-range coherence.

1. J.D. Whalen et al. Phys. Rev. A 100, 011402(R) (2019)