基于光机晶体微腔片上量子基态的研究

The project will focus on the study of an optomechanical cavity for the realization of on-chip quantum ground state. Different from the method of laser cooling, achieving a single-atom level quantum ground state, a macro/meso-scopic quantum ground state can be realized by use of optomechanics, which expands the manipulated object of quantum states to the quasiparticle - phonon. Meanwhile, based on the advanced micro/nano-fabrication technologies, the quantum ground state of an on-chip system can be expected. Thus, the ultimate noise of quantum fluctuations of the on-chip system can be greatly suppressed. It can be predicted that the realization of on-chip quantum ground state by optomechanics will intrigue a revolution in the progress of quantum control, precision measurement, and quantum information. In this project, aiming at the realization of on-chip quantum ground state, we will firstly study the optomechanical cavity based on the backaction cooling theory in optomechanics. Here, the physical picture of the interaction between the optical mode (photon) and the mechanical mode (phonon) will be clarified. Then, by designing the air-bridge or cantilever microcavity structure with both photonic bandgap and phonon bandgap, high-Q factor optomechanical crystal cavity will be fabricated in semiconductor material. At last, the frequency of the optical and the mechanical mode will be measured to evaluate the properties of the optomechanical crystal cavity. In conclusion, these research results will pave the way for systematic innovations in optomechanics from the theory, to the fabrication and test technology.

本申请项目将开展基于腔光机力学的片上量子基态的相关研究。不同于仅能实现单原子水平量子基态的激光冷却方案，利用腔光机力学可以实现宏观/介观尺度系统的量子基态，使得量子态的操控对象拓展到准粒子- - 声子，为实现片上系统的量子基态提供了可能的途径。可以预见，利用腔光机力学实现片上系统的量子基态，将引发量子控制、精密测量、量子信息领域研究的革命性飞跃。 本申请项目以光机晶体微腔实现片上量子基态的研究为目标，着眼于光机晶体微腔中光波/光子模式与机械振动/声子模式相互作用的丰富物理内涵，采用同时具有光子带隙和声子带隙的空气桥/悬臂微腔结构，在半导体材料上制备出高质量光机晶体微腔，并测试出光波模式与机械振动/声子模式的本征频率，形成从理论设计、工艺实现到测试技术的系统性创新研究。

光机晶体微腔是近几年迅速引起关注的新兴研究方向，利用光机晶体微腔可以同时局域和调控光子、声子并操控其相互作用过程，从而可将介观/宏观尺度的片上系统致冷至量子基态。通过本项目的实施，我们的研究工作直接瞄准光机晶体微腔中光子与声子的相互作用及片上量子基态的实现机理展开研究，在理论研究、设计实现到测试技术上取得了关键性突破。目前我们提出了啁啾光机晶体微腔、异质光机晶体微腔，突破了器件干法和湿法刻蚀，空气桥纳米悬臂结构、集成光输入输出耦合结构等多项关键技术瓶颈，成功研制出了国内首个片上光机晶体微腔。搭建了光机腔波导端面耦合测试系统，实现了5.66GHz声子模式的测试，这是已报道一维光机晶体微腔的最高声子频率。项目成果并得到国际、国内同行认可，发表论文13篇，其中SCI收录5篇，EI收录8篇，申请专利1项，国际国内会议上做特邀报告6次。这些成果为进一步实现基于光机晶体微腔的新型应用和片上器件打下了坚实的基础。