Generalized hydrodynamics in strongly interacting 1D Bose gases (I)

The dynamics of strongly interacting many-body quantum systems are notoriously complex and difficult to simulate. One-dimensional (1D) Bose gases can be studied experimentally with great precision and so are ideal for testing new dynamical theories. One such theory, generalized hydrodynamics (GHD), promises to efficiently simulate nearly-integrable systems by focusing on the evolution of the distribution of rapidities, which are the momenta of emergent quasiparticles. We experimentally test GHD with 1D Bose gases by suddenly increasing the trap depth in both the strong and intermediate coupling regimes and directly observing the rapidity distributions as they evolve [1]. We find excellent agreement between the experiment and GHD theory for long times after the trap quench, with dimensionless coupling parameters that range from 0.3 to 9.3, demonstrating that the approximations that underlie GHD are appropriate for many cold atom experiments. We also measure the momentum distributions after the quench, which allows us to observe the way in which the quasiparticles themselves evolve.
[1] N. Malvania, Y. Zhang, Y. Le, J. Dubail, M. Rigol, and D. S. Weiss, arXiv:2009.06651.