Speaker: Servaas Kokkelmans, Department of Applied Physics at Eindhoven University of Technology

Title: Van der Waals universality near a quantum tricritical point

Abstract: The elastic scattering properties of three bosons at low energy enter the many-body description of ultracold Bose gases via the three-body scattering hypervolume D. We study this quantity for identical bosons that interact via a pairwise finite-range potential. Our calculations cover the regime from strongly repulsive potentials towards attractive potentials supporting multiple two-body bound states and are consistent with the few existing predictions for D. We present a numerical confirmation of the universal predictions for D in the strongly interacting regime, where Efimov physics dominates, while in the weakly-interacting regime we find that the real part of D behaves surprisingly universally. We use this result to make quantitative predictions for the thermodynamics and elementary excitations of an atomic Bose-Einstein condensate (BEC) in the vicinity of a quantum tricritical point, including quantum droplets stabilized by effective three-body interactions.

Coffee/tea and cake from 14:00