Quantum Dynamics of Attractive and Repulsive Polarons in a Doped MoSe${}_2$ Monolayer

Abstract

When mobile impurities are introduced and coupled to a Fermi sea, new quasiparticles known as Fermi polarons are formed. There are two interesting, yet drastically different regimes of the Fermi polaron problem: (I) the attractive polaron (AP) branch, connected to pairing phenomena spanning the crossover from BCS superfluidity to the Bose-Einstein condensation of molecules; and (II) the repulsive branch (RP), which underlies the physics responsible for Stoner's itinerant ferromagnetism. Here, we study Fermi polarons in two dimensional systems, where many questions and debates regarding their nature persist. The model system we investigate is a doped MoSe${}_2$ monolayer. We find the observed AP-RP energy splitting and the quantum dynamics of attractive polarons agree with the predictions of polaron theory. As the doping density increases, the quantum dephasing of the attractive polarons remains constant, indicative of stable quasiparticles, while the repulsive polaron dephasing rate increases nearly quadratically. The dynamics of Fermi polarons are of critical importance for understanding the pairing and magnetic instabilities that lead to the formation of rich quantum phases found in a wide range of physical systems including nuclei, cold atomic gases, and solids.

7 pages, 4 figures

References in corpus (9)

• Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms
• Attractive and repulsive Fermi polarons in two dimensions
• Repulsive Fermi polarons in a resonant mixture of ultracold ${}^6$Li atoms
• Many-Body Theory of Trion Absorption Features in Two-Dimensional Semiconductors
• Valley Phonons and Exciton Complexes in a Monolayer Semiconductor
• Electron-exciton interactions in the exciton-polaron problem
• Observation of coherent multiorbital polarons in a two-dimensional Fermi gas
• Many-body exciton and inter-valley correlations in heavily electron-doped WSe${}_2$ monolayers
• Many-body effects of a two-dimensional electron gas on trion-polaritons

Cited by in corpus (1)

• Interplay of valley polarized dark trion and dark exciton-polaron in monolayer WSe2