Transient Quantum Optomechanics in Silica Microresonators

宏观机械振荡器如吉他弦、音叉或鼓膜的振动可以用经典物理学很好地描述。然而，如果机械振荡器被冷却到足够低的温度，使得热机械运动变得可以忽略不计，那么情况就不再是这样了。在这个极限下，机械振荡器的行为可以像包含离散数量或量子振动能量的量子力学系统一样。最近的实验和理论研究已经为将这些量子行为用于量子信息处理和制造更好的传感器铺平了道路。然而，将机械振荡器冷却到所需的超低温是困难的。这个项目的主要目标是探索实验方法，即使在存在显著的热噪声的情况下(即在高温下)，也可以保持或保持所需的量子过程或性质。该项目利用了特殊类型的相互作用，在完成相关的量子操作后，将机械振荡器恢复到其原始状态。这些量子操作可以在高温下运行，而不需要将机械振荡器冷却到量子基态的复杂性和技术挑战。该实验项目还为研究生和本科生提供了在科学和技术重要领域的培训机会。这种培训为学生在学术界、工业界或政府的职业生涯做好准备。实验研究将在多模光机械系统中进行，该系统通过三重共振布里渊散射将声学回音廊模式(WGM)耦合到片上二氧化硅微球中的光学WGMS。该系统充分利用了光学WGMS的超高精细度和声学WGMS的无夹紧损耗的特点。这项研究将使用一类光学机械哈密顿量，它在所需的相干操作后将机械振子返回到其初始状态，从而解开光学和机械系统的纠缠。这些操作类似于在热环境中囚禁离子纠缠的Sorensen-Molmer机制。光机械pi脉冲可以在不改变机械系统的情况下，引起两个相关光学模式之间的状态交换，将用于实现机械介导的光学状态转移。失谐边带耦合，例如将Sorensen-Molmer囚禁离子纠缠方案扩展到玻色光学机械系统，将被用于机械介导的光学纠缠。这些耐热的光学机械操作可以在开发能够在容易到达的热环境中工作的光学机械量子接口方面发挥重要作用。

Vibrations of macroscopic mechanical oscillators such as a guitar string, a tuning fork, or a drum membrane can be well described with classical physics. This is no longer true, however, if the mechanical oscillators are cooled to sufficiently low temperature such that thermal mechanical motion becomes negligible. In this limit the mechanical oscillators can behave like quantum mechanical systems that contain discrete amounts, or quanta, of vibrational energy. Recent experimental and theoretical research has paved the way to use these quantum behaviors for quantum information processing and to make better sensors. Cooling mechanical oscillators to the required ultra-low temperatures, however, is difficult. The primary goal of this project is to explore experimental approaches that can maintain or preserve the desired quantum processes or properties even in the presence of significant thermal noise (i.e., at elevated temperature). The project exploits special types of interactions that return the mechanical oscillator to its original state after the completion of the relevant quantum operations. These quantum operations can function at elevated temperature without the complexity and technical challenge of cooling the mechanical oscillator to its quantum ground state. The experimental project also provides training opportunities for graduate and undergraduate students in areas of both scientific and technological importance. This training prepares the students for careers in academia, industry, or government. The experimental research will be carried out in a multimode optomechanical system that couples acoustic whispering gallery modes (WGMs) to optical WGMs in an on-chip silica microsphere via triply resonant Brillouin scattering. This system takes full advantage of optical WGMs that feature ultrahigh finesse and acoustic WGMs that have no clamping loss. This research will use a class of optomechanical Hamiltonian that returns the mechanical oscillator to its initial state after the desired coherent operations, thus disentangling the optical and mechanical systems. These operations resemble the Sorensen-Molmer mechanism for entanglement of trapped ions in a thermal environment. Optomechanical pi-pulses which can induce state swapping between two relevant optical modes, but leave the mechanical system unchanged, will be used for the implementation of mechanically-mediated optical state transfer. Detuned sideband coupling, such as that which extends the Sorensen-Molmer entanglement scheme for trapped ions to the bosonic optomechanical system, will be used for mechanically-mediated optical entanglement. These thermally-robust optomechanical operations can play an important role in developing optomechanical quantum interfaces that can function in an easily accessible thermal environment.