利用表面声波对量子点与光子晶体微腔耦合的动态调控

Coherent control of interaction between light and matter at quantum level can be implemented by quantum dot based cavity quantum electrodynamics system, which has great potential applications in quantum computation, quantum communication and quantum metrology with quantum photonic network. Quantum bits and single photon sources have been realized by tuning the interaction between a single quantum dot and a photonic crystal cavity with changing the sample temperature or applying an external magnetic field, however, the tuning speed is very slow which limits the real application for such systems. Surface acoustic waves (SAWs) provide a tuning method for quantum dot energy and cavity mode in a high speed of GHz. In this project, SAWs will be used to tune the coupling between quantum dots and photonic crystal cavity dynamically, especially for strong coupling, and finally realize a quantum dot based hybrid system of cavity optomechanics. The project will include the design and fabrication of the SAWs devices integrated with quantum dot-cavity coupling system, controlling quantum dot energy and cavity mode by SAWs and investigating the tuning mechanism. The optical properties of the coupling system in different coupling strengths will be investigated with dynamically tuning by SAWs to achieve highly efficient single photon emission with weakly coupling effect and Rabi oscillations in strong coupling regime. Finally the coupling among quantum dot, phonons and photons will be investigated in a hybrid cavity optomechanics system for applications in quantum photonic network.

基于量子点的腔量子电动力学系统可以在量子水平上对光与物质之间的相互作用进行相干控制，有望通过量子光学网络实现量子计算、量子通信以及量子计量学等应用。通过温度或者磁场调控点与微腔的相互作用可以实现高度相干量子比特或者单光子光源，但是慢的操控速度抑制了该方法的实际应用，而表面声波提供一种调节量子点能级以及微腔模式的频率可达GHz的新方法。本课题利用表面声波对量子点与光学微腔的耦合进行动态调节，实现强耦合的动态可控，最终实现基于量子点的混合型的腔光力系统。主要研究内容包括：设计并制备集成声表面波结构和量子点-微腔耦合体系的器件；研究表面声波对量子点能级以及光学微腔的调节，探索调控的机制；利用表面声波动态调节量子点-光学微腔在不同耦合强度下的光学性质，研究弱耦合下的高效单光子发射以及强耦合下的拉比振荡；进一步研究量子点-声子-光子之间的强相互作用下的混合腔光力学系统，拓展在量子光学网络中的应用。

声表面波可以调控和耦合不同的物理系统。通过将高频声表面波引入光学微腔和低维半导体结构中，可以实现对低维半导体结构、微腔以及两者耦合的快速调控。这对于探索混合量子腔光力学系统中的相互作用，扩展基于量子点量子比特的新应用有着重要意义。具体实现方式是通过数值模拟, 特定高频率的声表面波由插指电极在压电材料GaAs表面上产生。为了研究声波表面波对不同结构的调控，本项目通过共聚焦低温荧光光谱和光电流研究了GaAs基自主装半导体量子点的光电性质，包括单量子点中空穴间库仑排斥作用诱导的巨大的光电流增强现象，磁场对量子点中载流子隧穿的调节作用以及单量子点中中性和带电激子的g因子各向异性。再者，为了利用不同光学结构，研究了量子点在交叉波导中的手性传播以及正常和反常抗磁行为量子点的圆偏振光在波导中的单向传输；设计了基于拓扑慢光边界态的拓扑腔和新型L3光子晶体微腔；实现了拓扑角态微腔与单个量子点的耦合以及受控回音壁式微盘腔与单个量子点的耦合。为了进一步拓展声表面波对不同低维半导体结构的调控，研究了单层WSe2中缺陷相关的单光子发光，MoS2中极少数激子与表面等离子激元纳米微腔的强耦合等。在项目的资助下，共发表SCI论文26篇和1篇综述，其中包括Physical Review applied 3篇，Laser & Photonics Reviews 3篇，Light: Science & Applications 2篇，Optics Express 2 篇， Applied Physics Letters 3篇，Nano Letters 1，Nanoscale 1 篇，Small 1篇，Advanced Quantum Technologies 1篇，Nano Research 1 篇，Chinese Physics Letters 1 篇, Npj 2D materials and Applications 1篇，Science China Physics Mechanics & Astronomy 1篇, Physical Review Materials 1篇, Nanotechnology 1篇, Journal of Physical Chemistry Letters 1篇，物理学报2篇以及科学通报评述1篇，申请并授权专利1项。