Instituto de Física, Universidade de Brasília, Brasília-DF 70919-970, Brazil.
Department of Physics, Qufu Normal University, Qufu, Shandong, 273165, China.
Sci Rep. 2017 Jan 23;7:41044. doi: 10.1038/srep41044.
Photonic quantum computer, quantum communication, quantum metrology and quantum optical technologies rely on the single-photon source (SPS). However, the SPS with valley-polarization remains elusive and the tunability of magneto-optical transition frequency and emission/absorption intensity is restricted, in spite of being highly in demand for valleytronic applications. Here we report a new class of SPSs based on carriers spatially localized in two-dimensional monolayer transition metal dichalcogenide quantum dots (QDs). We demonstrate that the photons are absorbed (or emitted) in the QDs with distinct energy but definite valley-polarization. The spin-coupled valley-polarization is invariant under either spatial or magnetic quantum quantization. However, the magneto-optical absorption peaks undergo a blue shift as the quantization is enhanced. Moreover, the absorption spectrum pattern changes considerably with a variation of Fermi energy. This together with the controllability of absorption spectrum by spatial and magnetic quantizations, offers the possibility of tuning the magneto-optical properties at will, subject to the robust spin-coupled valley polarization.
基于二维单层过渡金属二卤族化物量子点（QD）中空间局域载流子的新型单光子源（SPS），其具有确定的谷偏振，可实现磁光跃迁频率和发射/吸收强度的可调谐性，从而解决了光子量子计算机、量子通信、量子计量学和量子光学技术中对单光子源（SPS）的需求。我们证明了在 QD 中，光子以不同的能量但确定的谷偏振被吸收（或发射）。自旋耦合的谷偏振在空间或磁场量子化下保持不变。然而，随着量子化的增强，磁光吸收峰发生蓝移。此外，吸收光谱图案随费米能的变化而发生很大变化。这与通过空间和磁场量子化来控制吸收光谱相结合，提供了在稳健的自旋耦合谷偏振的前提下，随意调节磁光特性的可能性。
