Fate of an impurity strongly interacting with a thermal Bose gas

Abstract:

We spectroscopically study mobile impurities immersed in a homogeneous bosonic bath (a box-trapped Bose gas), varying the bath temperature and the strength of impurity-bath interactions. We compare our results to those for a quasipure Bose-Einstein condensate (BEC), and find that for strong impurity-bath interactions, the spectra narrow with increasing temperature, while the impurity energy shift is suppressed. Near the critical temperature for condensation, many-body effects still play an important role, and only for a nondegenerate bath, the system approaches the classical Boltzmann-gas behavior. The key spectral features are reproduced within the theory of an ideal Bose polaron.

J. Etrych, S. J. Morris, S. M. Fischer, G. Martirosyan, C. J. Ho, M. Drescher, M. Salmhofer, Z.
Hadzibabic, T. Enss, C. Eigen, „Fate of an impurity strongly interacting with a thermal Bose
gas“, 8. Aug. 2025, arXiv:2508.06493 (2025).

https://arxiv.org/abs/2508.06493

Related to Project C03, ABC