Department of Physics, Stevens Institute of Technology , Hoboken, New Jersey 07030, United States.
Center for Quantum Science and Engineering, Stevens Institute of Technology , Hoboken, New Jersey 07030, United States.
ACS Nano. 2017 Nov 28;11(11):11550-11558. doi: 10.1021/acsnano.7b06444. Epub 2017 Oct 18.
Monolayer photonic materials offer a tremendous potential for on-chip optoelectronic devices. Their realization requires knowledge of optical coherence properties of excitons and trions that have so far been limited to nonlinear optical experiments carried out with strongly inhomogeneously broadened material. Here we employ h-BN-encapsulated and electrically gated MoSe to reveal coherence properties of trion species directly in the linear optical response. Autocorrelation measurements reveal long dephasing times up to T = 1.16 ± 0.05 ps for positively charged excitons. Gate-dependent measurements provide evidence that the positively charged trion forms via spatially localized hole states, making this trion less prone to dephasing in the presence of elevated hole carrier concentrations. Quantum beat signatures demonstrate coherent coupling between excitons and trions that have a dephasing time up to 0.6 ps, a 2-fold increase over those in previous reports. A key merit of the prolonged exciton/trion coherences is that they were achieved in a linear optical experiment and thus are directly relevant to applications in nanolasers, coherent control, and on-chip quantum information processing requiring long photon coherence.
单层光子材料为片上光电设备提供了巨大的潜力。它们的实现需要了解激子和三电子的光学相干特性，这些特性迄今为止仅限于用强烈非均匀展宽材料进行的非线性光学实验。在这里，我们采用 h-BN 封装和电控的 MoSe 来直接在线性光学响应中揭示三电子物质的相干特性。自相关测量显示，正电荷激子的退相时间长达 T = 1.16 ± 0.05 ps。门控依赖性测量提供了证据，表明正电荷三电子物质通过空间局域的空穴态形成，这使得三电子物质在存在升高的空穴载流子浓度时不易退相。量子拍频特征证明了激子和三电子物质之间的相干耦合，其退相时间长达 0.6 ps，比以前的报道增加了两倍。延长激子/三电子相干的一个关键优点是，它们是在一个线性光学实验中实现的，因此与需要长光子相干的纳米激光器、相干控制和片上量子信息处理中的应用直接相关。
