基于片上回音壁模光学微腔的光力量子基态冷却

Recently, the ground state cooling of cavity optomechanical systems have attracted more and more attention for its potential applications in ultra-sensitive measurements such as displacement, force, mass, as well as to validate the quantum mechanics in macroscopic systems. In this project, we will focus on the study of the chip-based whispering-gallery mode cavity optomechanical systems and cooling the optomechanical oscillators to the ground state. We plan to fabricate chip-based high mechanical frequency (GHz) cavity optomechanical systems with both high optical Q-factors and high mechanical Q-factors by optimizing the fabrication recipe of the microcavities. We will try to cool the high mechanical frequency mode to the ground state using the resolved sideband cooling method, since the initial phonon number is lower for higher mechanical frequency mode under a certain temperature. In addition, we will investigate the multi-mode cooling to enhance the dynamical backaction using coupled high-Q microtoroid cavities. After the realization of the ground state cooling, we will further study the application of the cavity optomechanical system such as the accelerometer and gyroscope. In addition, we will study the optomechanical phonon laser as well as its application for precision measurements.

腔光力学系统的量子基态冷却是目前国际上光学研究的热点问题，对于实现位移、力、质量等物理量的精密测量和验证宏观量子物理现象有非常重要的应用价值。本课题主要研究基于研究片上回音壁模式微腔的光力学系统，目标是实现其量子基态冷却。我们将通过优化工艺实现高机械频率（GHz）和高光学（力学）品质因子的光力学系统。由于同温度下高频率振子的初始声子数较低，利用边带冷却技术，光力学系统逼近量子基态将更为可行。我们还将实现基于耦合微环芯腔的多腔模冷却实验，利用腔模对光力动态反作用的增加来提高冷却效率，降低噪声，实现量子基态冷却。在逼近量子基态之后，我们将研究光力学系统如何对加速度、角速度等物理量进行精密测量。我们还将研究如何实现高频声子激光及其精密测量应用。

腔光力学系统的量子基态冷却是目前国际上光学研究的热点问题，对于实现位移、力、质量等物理量的精密测量和验证宏观量子物理现象有非常重要的应用价值。本课题实现了多种基于回音壁模微腔及微腔耦合系统的光力学系统，其光学品质因子可以达到1亿，力学品质因子达到2万。基于这些系统，我们研究边带冷却和多模光力冷却。利用基于表面声波的多模光力冷却，我们将410 MHz力学模式的声子数在室温条件下冷却到了1500以内。利用耦合光学微腔系统，我们分别实现了59 MHz和 448 MHz的低阈值声子激光。我们研究了光力冷却的量子动力学过程，我们发现系统最终剩余的热声子数与冷却速率相关。在光力冷却的应用方面，我们研究了基于光力系统的高精度重力精密测量。理论计算表面，重力加速度测量的相对精度在当前的实验条件下有望达到10^-10。另外，我们在真空条件下光束缚的纳米金刚石系统中首次观察到了扭动自由度的运动，扭动模式的频率比同一系统质心平动模式频率大一个量级以上。项目执行期间，我们发表了50篇SCI论文。包括Phys. Rev. Lett. 5篇、Nat. Commun. 1篇、Laser Photonics Rev.2篇、Phys. Rev. A 12篇等。

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