Quantum Dynamics of Attractive and Repulsive Polarons in a Doped MoSe2 Monolayer
Quantum Dynamics of Attractive and Repulsive Polarons in a Doped MoSe2 Monolayer
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DOI：
10.1103/physrevx.13.011029
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发表时间：
2023-03-02
影响因子：
12.5
通讯作者：
Li, Xiaoqin
中科院分区：
文献类型：
--
作者：
Huang, Di;Sampson, Kevin;Li, Xiaoqin
当移动的杂质被引入并耦合到费米海时，形成了称为费米极化子的新准粒子。费米极化子问题有两个有趣但截然不同的领域：（i）吸引极化子（AP）分支与跨越BCS超流性到玻色-爱因斯坦凝聚的分子的配对现象有关;（ii）排斥极化子（RP），它是Stoner巡游铁磁性的物理基础。在这里，我们研究费米极化子在二维系统中，许多问题和争论，关于他们的性质仍然存在。我们研究的模型系统是一个掺杂的MoSe 2单层。我们发现所观察到的AP-RP能裂和吸引极化子的量子动力学与极化子理论的预言一致。随着掺杂密度的增加，吸引极化子的量子退相保持恒定，表示稳定的准粒子，而排斥极化子退相速率几乎以二次方增加。费米极化子的动力学对于理解配对和磁不稳定性至关重要，这些不稳定性导致在包括原子核，冷原子气体和固体在内的广泛物理系统中形成丰富的量子相。
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 MoSe2 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.