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arXiv:2504.07227

Mott transition in excitonic Bose polarons

E. A. Szwed, Brian Vermilyea, D. J. Choksy, Zhiwen Zhou, M. M. Fogler, Леонид Викторович Бутов, K. W. Baldwin, Loren N. Pfeiffer

Published Apr 9, 2025• 0 citations
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Abstract

For a neutral system of positive and negative charges, such as atoms in a crystal, increasing the density causes the Mott transition from bound electrons to free electrons. The density of optically generated electron-hole systems can be controlled in situ by the power of optical excitation that enables the Mott transition from excitons, the bound pairs of electrons and holes, to free electrons and holes with increasing density. These Mott transitions occur in systems of pairs of the same kind, such as atoms or excitons. However, a different type of the Mott transition can occur for Bose polarons. A Bose polaron is a mobile particle of one kind in a Bose gas of particles of another kind. For the Mott transition in polarons, the polaron states vanish with increasing density of the surrounding gas. In this paper, we present the observation of this type of the Mott transition and the measurement of the Mott transition parameter $n_{\rm M}^{1/2} a_{\rm B}$ in 2D excitonic Bose polarons.

DOI
10.48550/arxiv.2504.07227

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The authors perform here large-scale quantum Monte Carlo simulations in the grand-canonical ensemble to characterize a mobile impurity in a 2D Bose--Hubbard bath. They find that the polaron effective mass is a reliable probe of the Mott--superfluid transition only at weak coupling, while strong impurity--bath interactions induce MI\ifmmode\pm\else\textpm\fi{}1 bound states with suppressed mobility. The work delivers controlled benchmarks across interaction strengths and clarifies how impurity physics manifests in experimentally relevant trapped atom systems.