Non-equilibrium quantum dynamics and formation of the Bose polaron

Advancing our understanding of non-equilibrium phenomena in quantum many-body systems remains one of the greatest challenges in physics. Here we report on the experimental observation of a paradigmatic many-body problem, namely the non-equilibrium dynamics of a quantum impurity immersed in a bosonic environment(1,2). We use an interferometric technique to prepare coherent superposition states of atoms in a Bose-Einstein condensate with a small impurity-state component, and monitor the evolution of such quantum superpositions into polaronic quasiparticles. These results offer a systematic picture of polaron formation(3-7) from weak to strong impurity interactions. They reveal three distinct regimes of evolution with dynamical transitions that provide a link between few-body processes and many-body dynamics. Our measurements reveal universal dynamical behaviour in interacting many-body systems and demonstrate new pathways to study non-equilibrium quantum phenomena.

Automated summary

Advancing our understanding of non-equilibrium phenomena in quantum many-body systems remains a major challenge in physics. The experimental observation of the non-equilibrium dynamics of a quantum impurity immersed in a bosonic environment reveals a systematic picture of polaron formation and provides a link between few-body processes and many-body dynamics. The measurements demonstrate universal dynamical behavior in interacting many-body systems and offer new pathways to study non-equilibrium quantum phenomena.