The properties of strongly interacting quantum many-body systems are usually quite challenging to describe, both theoretically and experimentally. We, Rafał and our colleagues, investigated via a hydrodynamic approach, the excitations of one-dimensional repulsive Bose gas for arbitrary interaction strength.

We observed a good agreement between our approach and exact solutions of the Lieb-Liniger model for the particle modes and the discrepancies for the hole modes.

Therefore, the hydrodynamical equations we found were useful for long-wave structures like phonons, and were of a limited range of applicability for short-wave ones like narrow solitons.

Beyond Gross-Pitaevskii equation for 1D gas: quasiparticles and solitons

·      J. Kopyciński, M. Łebek, M. Marciniak,  R. Ołdziejewski, W. Górecki,  K. Pawłowski, Gross-Pitaevskii equation for 1D gas: quasiparticles and solitons, SciPost Phys. 12, 023 (2022)