Fig. 2: Elastic and inelastic collisions.
From: Evaporation of microwave-shielded polar molecules to quantum degeneracy
a, Rate coefficients for elastic (orange) and inelastic (blue) scattering events. The solid and dashed lines show coupled-channel calculations for a thermal sample with T = 800 nK and a degenerate sample with T = 30 K = 0.4TF, respectively. The data points show the measurement results for T = 800 nK. The shaded area indicates the limit for measurements of the elastic collision rate imposed by the hydrodynamic regime. On resonance, the Rabi frequency is Ω ≈ 2π × 11 MHz. The triangular markers on the side indicate the calculated inelastic rate coefficients in the absence of a microwave field. The error bars are the standard deviation from the fit to the differential equations. b, Examples of cross-thermalization measurements at Δ = 2π × 30 MHz (bright) and Δ = 2π × 80 MHz (dark). In the latter case, βel is consistent with zero within the error bars. The error bars are the standard error of the mean of four repetitions. The lines are fits of a coupled differential-equation system modelling the collision rates (Methods). c, The ratio γ of elastic-to-inelastic collision rates based on the measurements and calculations presented in a. The error bars denote the standard deviation.
