String Theory Journal Club

The last few years have witnessed a sustained deepening of the collaboration between experimentalists working on cold atom gases and theorists studying interacting many-body quantum systems in and out of equilibrium. On the theoretical side however, obtaining analytical results for strongly interacting quantum systems becomes almost impossible, with the exception of 1d Bethe ansatz solvable models. The Bose gas with contact interactions is one such example, that is moreover experimentally realizable. Interestingly, the Bose gas with attractive interactions is build from bound states but it is experimentally highly unstable in its equilibrium phase. Once pushed out of equilibrium, the Bose gas and its bound states are stabilized due to its underlying integrability structure. In this talk I will present our analytical results on the production of bound states through slow interaction changes from the repulsive to the attractive regime, using the recently developed framework of Generalized Hydrodynamics (GHD). The inherent difficulty to test our predictions by numerical benchmarks in the quantum realm has motivated us to study its semiclassical limit: we apply our ideas to the Non-Linear-Schrödinger equation, and we benchmark our analytical predictions against Monte Carlo simulations. Finally, our results are realized in a state-of-the-art experiment with cold Cesium atoms.