Generalized Hydro Dynamics (GHD) emerged as a very powerful tool to describe 1d systems. After a very brief introduction, I will first present a way to extend GHD to the dimensional cross over regime [1] and highlight the experimental tests of standard and extended GHD. In the second part of my talk, I will highlight how GHD can give us a much-improved understanding of the excitations and their decay/dephasing in a 1d Bose gas and highlights the relationship between many-body interactions and dimensionality. In our experiments we prepare a single mode of excitations and watch it decay. We find that the decay of the excitations is perfectly described with DHD and 1D behaviour can extend deep into the three-dimensional (3D) crossover. We attribute our observations to an emergent Pauli blocking of 3D excitations, caused by the rapidities assuming fermionic statistics, despite the gas being purely bosonic [2].
Supported by DFG-FWF: SFB ISOQUANT.
[1] F. Moller, et al., Phys.Rev.Lett. 126, 090602 (2021)
[2] F. Cataldini et al., arXiv:2111.13647