Abstract
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.
Highlights
The independent electron-hole picture and consider the effect of electron-hole interaction on the absorption spectrum
The two-band model proposed by Xiao et al.[18], which can correctly capture the salient features of the density functional theory calculated band structure and predict/interpret the experimental observations, is widely adopted[4,10,22,23,24]
To verify that our two-band k.p model[18] can well describe the low-energy physics of monolayer MoS2, we have performed a comparison of our result, with that calculated by the density functional theory (DFT)[27] and that obtained by the k.p models of second and third orders[19,21,25,28], see Supplementary material (SM), Sec
Summary
The independent electron-hole picture and consider the effect of electron-hole interaction (i.e., excitonic effect) on the absorption spectrum. Optical absorption of TMDC QDs excited by circularly polarized light at zero field. The QDs inherit the valley and spin dependent optical selection rule from their counterpart of 2D bulk MoS2.
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