The talk will focus on two different stories, Bose polarons in an optical box and turbulent equation of state in Gross Pitaevskii (GP) model.
We study the general problem of an impurity immersed in a bath of bosons (Bose polaron). In our case, the bath is a homogeneous BEC of 39K atoms, produced in an optical-box trap. The impurities are formed using rf-injection between spin states, and the interstate interactions are tuned using magnetic Feshbach resonances. Leveraging the suppression of inhomogeneous broadening in a box-trapped gas, we use a combination of injection spectroscopy and Ramsey-like many-body interferometry to access the injection spectrum (frequency domain) and the impurity-coherence function (time domain) for both attractive and repulsive interactions. We find that the impurity physics is universally set by the bath density across the whole range of interactions.
Finding universal features in far-from-equilibrium systems, similar to those in their equilibrium counterparts, is a major ongoing challenge. In a recent experimental study (Nature 620, 521–524), a universal equation of state was constructed for a turbulent gas. We numerically study the same system within the mean field Gross-Pitaevskii equation and find that it can also be described by a universal equation of state, but that its form differs from the experimental one.
Host: Nir Navon
