Many-body quantum dynamics, induced correlations and bound states of Bose polarons

We unravel the ground state properties and the nonequilibrium dynamics of spinor impurities immersed in a bosonic gas following an interspecies interaction quench. For the ground state of non-interacting impurities we reveal signatures of attractive induced interactions and the formation of bipolaron states, whilst a direct impurity-impurity repulsion forces the impurities to stay apart. Turning to the quench dynamics we inspect the time-evolution of the contrast unveiling the existence, dynamical deformation and the orthogonality catastrophe of Bose polarons. It is shown that for an increasing postquench repulsion the impurities reside in a superposition of two distinct two-body configurations while at strong repulsions their corresponding two-body correlation patterns show a spatially delocalized behavior evincing the involvement of higher excited states. For attractive interspecies couplings, the impurities exhibit a tendency to localize and remarkably for strong attractions they experience a mutual attraction on the two-body level which signals the formation of a bipolaron state. To analyze and quantify induced impurity-impurity correlations, we construct an effective two-body Hamiltonian identifying the mean-field attraction and the corresponding correlations effects.