Hyperfine structure of nP1/2 Rydberg states in Rb85

Abstract

We measure the hyperfine structure of $n{P}_{1/2}$ Rydberg states for $n=$ 42, 43, 44, and 46 using mm-wave spectroscopy on an ensemble of laser-cooled $^{85}\mathrm{Rb}$ atoms. Systematic uncertainties in our measurement from the Zeeman splittings induced by stray magnetic fields and dipole-dipole interactions between two Rydberg atoms are factored in with the obtained statistical uncertainty. Our final measurement of the $n{P}_{1/2}$ hyperfine coupling constant is ${A}_{\text{HFS}}=1.443(31)$ GHz. This measurement is useful for studies of long-range Rydberg molecules, Rydberg electrometry, and quantum simulation with dipole-dipole interactions involving $n{P}_{1/2}$ atoms.