Temperature and pressure dependence of diffusion coefficients of Rb-inert gas mixtures using coherent scattering from optically pumped population gratings

We investigate the temperature dependence of diffusion coefficients of Rb atoms DRb(T,p) in the presence of N2 buffer gas. This work follows recent determinations of DRb(T,p) in 6 buffer gas mixtures over the pressure range of p = 50 to 760 Torr and at a constant temperature of T = 24°C. These measurements agree with quantum mechanical and classical calculations of collisions based on ab-initio interatomic potentials, to an accuracy ranging from 5.5% to 15% [Pouliot et. al., Phys. Rev. A 111, 033108 (2025)], suggesting that the determinations of diffusion coefficients D(T,p) can become the basis for a quantum pressure sensor. We report progress on these measurements and discuss suppression of systematic uncertainties arising from the heterodyne detection system.