近日，瑞典查尔姆斯理工大学的Janine Splettstoesser及其研究团队取得一项新进展。经过不懈努力，他们揭示 了具有一个频率依赖反射镜的耗散和色散腔光机械学。相关研究成果已于2024年4月29日在国际知名学术期刊《物理评论A》上发表。

在这项研究工作中，研究人员分析了一个光机械系统，其中一个反射镜是强频率依赖的，即一个悬挂的法诺反射镜。这一光机械系统由两种光学模式构成，这两种模式与悬挂式法诺反射镜的运动紧密耦合。研究人员构建了一个量子耦合模式的详尽描述，涵盖了标准的色散光力学耦合和耗散耦合。通过在线性区域内求解系统动力学的朗之万方程，他们发现，即便腔体本身并不处于可分辨边带区，依然可以通过强光模耦合实现室温下的基态冷却，从而有效实现边带分辨。

尤为关键的是，这一发现强调了根据有效激光失谐对腔输出光谱进行细致分析的重要性，以准确推断机械谐振器的声子占用情况。此外，这项研究工作还预测了在基于法诺的微腔中达到非线性量子光力学区域，如何通过设计法诺反射镜的特性。

据悉，光机械微腔通过限制光在亚波长范围内，显著增强了光与机械运动之间的相互作用，但这也导致了光学损耗率的增加。因此，基于微腔的光机械系统常处于不可分辨边带区，从而阻碍了基于边带的基态冷却。为了在这种系统中降低光学损耗，关键在于设计腔反射镜，即优化与机械谐振器相互作用的光学模式。

附：英文原文

Title: Dissipative and dispersive cavity optomechanics with a frequency-dependent mirror

Author: Juliette Monsel, Anastasiia Ciers, Sushanth Kini Manjeshwar, Witlef Wieczorek, Janine Splettstoesser

Issue&Volume: 2024/04/29

Abstract: An optomechanical microcavity can considerably enhance the interaction between light and mechanical motion by confining light to a subwavelength volume. However, this comes at the cost of an increased optical loss rate. Therefore, microcavity-based optomechanical systems are placed in the unresolved-sideband regime, preventing sideband-based ground-state cooling. A pathway to reduce optical loss in such systems is to engineer the cavity mirrors, i.e., the optical modes that interact with the mechanical resonator. In our work, we analyze such an optomechanical system, whereby one of the mirrors is strongly frequency dependent, i.e., a suspended Fano mirror. This optomechanical system consists of two optical modes that couple to the motion of the suspended Fano mirror. We formulate a quantum-coupled-mode description that includes both the standard dispersive optomechanical coupling as well as dissipative coupling. We solve the Langevin equations of the system dynamics in the linear regime showing that ground-state cooling from room temperature can be achieved even if the cavity is per se not in the resolved-sideband regime, but achieves effective sideband resolution through strong-optical-mode coupling. Importantly, we find that the cavity output spectrum needs to be properly analyzed with respect to the effective laser detuning to infer the phonon occupation of the mechanical resonator. Our work also predicts how to reach the regime of nonlinear quantum optomechanics in a Fano-based microcavity by engineering the properties of the Fano mirror.

DOI: 10.1103/PhysRevA.109.043532

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.043532