Determination of the s-wave Scattering Length of Chromium

Abstract

We have measured the deca-triplet s-wave scattering length of the bosonic chromium isotopes ${}^{52}$Cr and ${}^{50}$Cr. From the time constants for cross-dimensional thermalization in atomic samples we have determined the magnitudes $|a{(}^{52}Cr)|=(170\pm 39)a_0$ and $|a{(}^{50}Cr)|=(40\pm 15)a_0$, where $a_0=0.053nm$. By measuring the rethermalization rate of ${}^{52}$Cr over a wide temperature range and comparing the temperature dependence with the effective-range theory and single-channel calculations, we have obtained strong evidence that the sign of $a{(}^{52}Cr)$ is positive. Rescaling our ${}^{52}$Cr model potential to ${}^{50}$Cr strongly suggests that $a{(}^{50}Cr)$ is positive, too.

v3: corrected typo in y-axis scaling of Figs. 3 and 4