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arXiv · 2502.18678

Emergence of fermion-mediated interactions in Bose-Fermi mixtures

Esteban Cárdenas·Joseph K. Miller·David Mitrouskas·Nataša Pavlović
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Abstract

This work is inspired by recent experimental observations in ultracold atomic Bose-Fermi mixtures [DeSalvo et al., Nature 568 (2019)]. These experiments reveal the emergence of an attractive fermion-mediated interaction between bosons, as well as a stability-instability transition. We give the first mathematical demonstration of this transition by studying the low-energy spectrum of a many-body interspecies Hamiltonian. More precisely, we show the convergence of its eigenvalues towards those of an effective Bose Hamiltonian, which includes fermion-mediated effects. Applying this result to a model with short-range potentials, we derive a stability-instability transition in the bosonic subsystem, driven by the Bose-Fermi coupling strength $g$. For small $|g|$, the bosons form a stable Bose-Einstein condensate with the energy per particle uniformly bounded from below. For large $|g|$, the energy per particle is no longer uniformly bounded from below, signaling the collapse of the condensate.

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Esteban Cárdenas, Joseph K. Miller, David Mitrouskas, Nataša Pavlović. 2025-02-25. Emergence of fermion-mediated interactions in Bose-Fermi mixtures. https://arxiv.org/abs/2502.18678

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