Description
When a mobile exciton is immersed in a Fermi sea of charge carriers, it is dressed, forming attractive and repulsive polaron branches, whose low-energy physics is captured by the crossover between the trion and polaron pictures [1]. While this ground-state polaron physics is now well established, the fate of Rydberg-exciton states under doping — and their relationship to the excited trion resonances observed in experiment [2,3] — remains far less understood.
In this work we present a theoretical investigation of the optical response of doped two-dimensional transition-metal dichalcogenides that addresses this question directly. We employ a variational dressed-exciton ansatz including up to four-body correlations — an exciton dressed by a particle–hole excitation of the Fermi sea — which interpolates from the few-body bound states of the low-density limit to the many-body polaron states at finite doping within the continuum of the ground state trion.
We find that the excited Rydberg polarons exhibit a doping dependence qualitatively distinct from the ground-state polaron. In particular, the excited attractive branch is a composite state that draws oscillator strength from several exciton Rydberg states as the density increases.
[1] D. Efimkin et al., Phys. Rev. B 95, 035417 (2017).
[2] E. Liu et al., Nat. Commun. 12, 6131 (2021).
[3] A. Christianen et al., arXiv:2512.06893 (2025).
| I am the presenting author | Yes |
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