Dynamical formation of polarons in a Bose-Einstein condensate: A variational approach

We investigate the nonequilibrium dynamics of an impurity coupled to a Bose-Einstein condensate, systematically compared with recent experimental results [M. G. Skou et al., Nat. Phys. (2021)]. The dynamics of the impurity is tracked down by using a time-dependent variational coherent ansatz. For weak coupling between the impurity and the bath, analytical expressions for the time-dependent contrast are derived, matching quite well with previous findings obtained within a master equation approach. For strong coupling instead, the variational ansatz provides a good quantitative description of the polaron dynamics, in particular, in signaling the transition from the few- to the many-body correlated regime where polarons are expected to form.

Automated summary

The study investigates the nonequilibrium dynamics of an impurity coupled to a Bose-Einstein condensate, comparing it with recent experimental results. Analytical expressions for the time-dependent contrast are derived for weak coupling, matching previous findings. The variational ansatz provides a quantitative description of polaron dynamics in strong coupling, especially in signaling the transition from few- to many-body correlated regime where polarons are expected to form.