Momentum-correlated scattering spheres with macroscopic depletion in a Bose-Einstein condensate (BEC)

This work describes a combined experimental and theoretical study of momentum-correlated quantum mechanical scattering between atoms in a dilute-gas Bose-Einstein condensate. We focus on condensates with high enough densities such that a very rich sequence of multiple scattering events has to be taken into account. In our experiments, we generate a superposition of two different momentum states and image the resulting scattering effects in time-of-flight imaging. Scattering between particles in the same spin state or in different states can be induced. Our beyond-mean-field framework takes scattering cascades into account and qualitatively reproduces experimentally observed scattering spheres. A systematic study of quantum depletion and correlated scattering as a function of the initial population imbalance shows a surprising complexity of the dynamics even in conceptually simple experimental configurations.