Quasiparticle properties of long-range impurities in a Bose condensate
Year: 2025
Type: article
Abstract: An impurity immersed in a Bose condensate can form a quasiparticle known as a Bose polaron. When the impurity-boson interaction is short ranged and three-body Efimov correlations are neglected, the quasiparticle properties can be characterized in terms of the impurity-boson scattering length a IB and the condensate coherence length ξ . This description remains valid irrespective of the bath density n 0 . Long-ranged interactions—such as provided by Rydberg or ionic impurities—introduce an effective interaction range r eff as the third length scale. The interplay among these competing length scales raises the question of whether a robust description across different bath densities can still be maintained. In this study, we discuss the quasiparticle nature of long-range impurities and its dependence on the length scales n 0 − 1 / 3 , r eff , and ξ . We employ two complementary theories—the coherent-state ansatz and the perturbative Gross-Pitaevskii theory—which incorporate beyond-Fröhlich interactions. We derive an analytical expression for the beyond-Fröhlich effective mass for a contact interaction and numerically compute the effective mass for long-range impurities. We argue that the coupling parameter | a IB | n 0 1 / 3 remains the principal parameter governing the properties of the polaron. For weak ( | a IB | n 0 1 / 3 ≪ 1 ) and intermediate ( | a IB | n 0 1 / 3 ≃ 1 ) values of the coupling parameter, long-range impurities in a Bose condensate are well described as quasiparticles with a finite quasiparticle weight and a well-defined effective mass. However, the quasiparticle weight becomes significantly suppressed as the effective impurity volume is occupied by an increasing number of bath particles ( r eff n 0 1 / 3 ≫ 1 ).
Source: Physical Review A
DOI: 10.1103/7sfz-pzkh
Authors: T. Alper Yoğurt, Matthew T. Eiles
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $2,675
OpenAlex ID: W4417210258