Paper

Accurate determination of the scattering length of erbium atoms

Bohn, J L, Baier, S, Yang, B, Patscheider, A, Ferlaino, F, Mark, M J, Wang, R R W, Chomaz, L, Petter, D, Natale, G

2021

Overview

An accurate knowledge of the scattering length is fundamental in ultracold quantum gas experiments and essential for the characterisation of the system as well as for a meaningful comparison to theoretical models. Here, we perform a careful characterisation of the s-wave scattering length \\(a_s\\) for the four highest-abundance isotopes of erbium, in the magnetic field range from 0G to 5G. We report on cross-dimensional thermalization measurements and apply the Enskog equations of change to numerically simulate the thermalization process and to analytically extract an expression for the so-called number of collisions per re-thermalization (NCPR) to obtain \\(a_s\\) from our experimental data. We benchmark the applied cross-dimensional thermalization technique with the experimentally more demanding lattice modulation spectroscopy and find good agreement for our parameter regime. Our experiments are compatible with a dependence of the NCPR with \\(a_s\\), as theoretically expected in the case of strongly dipolar gases. Surprisingly, we experimentally observe a dependency of the NCPR on the density, which might arise due to deviations from an ideal harmonic trapping configuration. Finally, we apply a model for the dependency of the background scattering length with the isotope mass, allowing to estimate the number of bound states of erbium.

• Publisher: Cornell University Library, arXiv.org
• Subject: Erbium / Thermalization (energy absorption) / Wave scattering