Phenomenological model of decaying Bose polarons

Fuente: arXiv
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Hauptverfasser: Alhyder, Ragheed, Bruun, Georg M., Pohl, Thomas, Lemeshko, Mikhail, Volosniev, Artem G.
Format: Preprint
Veröffentlicht: 2025
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author Alhyder, Ragheed
Bruun, Georg M.
Pohl, Thomas
Lemeshko, Mikhail
Volosniev, Artem G.
author_facet Alhyder, Ragheed
Bruun, Georg M.
Pohl, Thomas
Lemeshko, Mikhail
Volosniev, Artem G.
contents Cold atom experiments show that a mobile impurity particle immersed in a Bose-Einstein condensate forms a well-defined quasiparticle (Bose polaron) for weak to moderate impurity-boson interaction strengths, whereas a significant line broadening is consistently observed for strong interactions. Motivated by this, we introduce a phenomenological theory based on the assumption that the most relevant states are characterized by the impurity correlated with at most one boson, since they have the largest overlap with the uncorrelated states to which the most common experimental probes couple. These experimentally relevant states can however decay to lower energy states characterised by correlations involving multiple bosons, and we model this using a minimal variational wave function combined with a complex impurity-boson interaction strength. We first motivate this approach by comparing to a more elaborate theory that includes correlations with up to two bosons. Our phenomenological model is shown to recover the main results of two recent experiments probing both the spectral and the non-equilibrium properties of the Bose polaron. Our work offers an intuitive framework for analyzing experimental data and highlights the importance of understanding the complicated problem of the Bose polaron decay in a many-body setting.
format Preprint
id arxiv_https___arxiv_org_abs_2507_04143
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Phenomenological model of decaying Bose polarons
Alhyder, Ragheed
Bruun, Georg M.
Pohl, Thomas
Lemeshko, Mikhail
Volosniev, Artem G.
Quantum Gases
Cold atom experiments show that a mobile impurity particle immersed in a Bose-Einstein condensate forms a well-defined quasiparticle (Bose polaron) for weak to moderate impurity-boson interaction strengths, whereas a significant line broadening is consistently observed for strong interactions. Motivated by this, we introduce a phenomenological theory based on the assumption that the most relevant states are characterized by the impurity correlated with at most one boson, since they have the largest overlap with the uncorrelated states to which the most common experimental probes couple. These experimentally relevant states can however decay to lower energy states characterised by correlations involving multiple bosons, and we model this using a minimal variational wave function combined with a complex impurity-boson interaction strength. We first motivate this approach by comparing to a more elaborate theory that includes correlations with up to two bosons. Our phenomenological model is shown to recover the main results of two recent experiments probing both the spectral and the non-equilibrium properties of the Bose polaron. Our work offers an intuitive framework for analyzing experimental data and highlights the importance of understanding the complicated problem of the Bose polaron decay in a many-body setting.
title Phenomenological model of decaying Bose polarons
topic Quantum Gases
url https://arxiv.org/abs/2507.04143