Coherent feedback control of two-dimensional excitons
Coherent feedback control of two-dimensional excitons
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DOI：
10.1103/physrevresearch.2.012029
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发表时间：
2019-02
影响因子：
4.2
通讯作者：
C. Rogers;D. Gray;Nate Bogdanowicz;T. Taniguchi;Kenji Watanabe;H. Mabuchi
中科院分区：
文献类型：
--
作者：
C. Rogers;D. Gray;Nate Bogdanowicz;T. Taniguchi;Kenji Watanabe;H. Mabuchi
电偶极辐射可通过相干光反馈来控制，正如先前通过调制光子环境对置于光学腔和金属镜附近的点偶极所进行的研究那样。在涉及荧光分子、囚禁离子和量子点的实验中，偶极的点特性、其小于1的量子效率以及退相干率共同严重限制了总线宽的任何变化。在此我们表明，单层二维（2D）材料二硒化钼（MoSe₂）中激子发射的横向相干性消除了先前实验中存在的许多基本物理限制。激子与位于MoSe₂和附近平面镜之间的光子模式之间的相干相互作用以干涉方式取决于镜子的位置，从而能够完全控制辐射耦合率从接近零到1.8毫电子伏特，以及激子总线宽从0.9到2.3毫电子伏特的相应变化。观察到这种调制所必需的高度辐射展宽的激子共振（在我们的样品中比例高达3∶1）因二维材料样品制备的最新进展而成为可能。我们的镜子平移方法不受单层中任何应变或直流电场耦合的影响，这使得能够对这种光子效应进行基础研究。我们实验中的弱相干驱动场产生的平均激发占据数约为10⁻³，因此我们的实验对应于在微扰量子电动力学范畴内探测辐射反应。这个系统将作为探索新的激子物理和量子非线性光学效应的试验台。
Electric dipole radiation can be controlled by coherent optical feedback, as has previously been studied by modulating the photonic environment for point dipoles placed both in optical cavities and near metal mirrors. In experiments involving fluorescent molecules, trapped ions and quantum dots the point nature of the dipole, its sub-unity quantum efficiency, and decoherence rate conspire to severely limit any change in total linewidth. Here we show that the transverse coherence of exciton emission in the monolayer two-dimensional (2D) material MoSe${}_2$ removes many of the fundamental physical limitations present in previous experiments. The coherent interaction between excitons and a photonic mode localized between the MoSe${}_2$ and a nearby planar mirror depends interferometrically on mirror position, enabling full control over the radiative coupling rate from near-zero to 1.8 meV and a corresponding change in exciton total linewidth from 0.9 to 2.3 meV. The highly radiatively broadened exciton resonance (a ratio of up to $3:1$ in our samples) necessary to observe this modulation is made possible by recent advances in 2D materials sample fabrication. Our method of mirror translation is free of any coupling to strain or DC electric field in the monolayer, which allows a fundamental study of this photonic effect. The weak coherent driving field in our experiments yields a mean excitation occupation number of ${\sim} 10^{-3}$ such that our experiments correspond to probing radiative reaction in the regime of perturbative quantum electrodynamics. This system will serve as a testbed for exploring new excitonic physics and quantum nonlinear optical effects.