Torsional Optomechanics of a Levitated Nonspherical Nanoparticle
Torsional Optomechanics of a Levitated Nonspherical Nanoparticle
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悬浮非球形纳米粒子的扭转光力学
DOI：
10.1103/physrevlett.117.123604
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发表时间：
2016-09-15
影响因子：
8.6
通讯作者：
Li, Tongcang
中科院分区：
文献类型：
--
作者：
Hoang, Thai M.;Ma, Yue;Li, Tongcang
真空中的光悬浮纳米粒子是一种用于宏观量子力学传感和研究的典型光机系统。虽然它的质心运动已被深入研究，其扭转振动仅在有限的情况下进行了理论研究。在这里，我们报告的第一个实验观察的扭转振动的光学悬浮非球形纳米粒子在真空中。我们利用光子的自旋角动量和非球形纳米粒子的扭转振动之间的耦合来实现这一点，纳米粒子的极化率是一个张量。扭转振动频率可以比其质心运动频率高1个数量级，这对于基态冷却是有希望的。我们提出了一个简单而新颖的方案，实现基态冷却的扭转振动与线偏振高斯腔模式。真空中悬浮的非球形纳米颗粒也将是超灵敏的纳米级扭转天平，在现实条件下具有10（-29）Nm/root Hz pHz量级的扭矩检测灵敏度。
An optically levitated nanoparticle in vacuum is a paradigm optomechanical system for sensing and studying macroscopic quantum mechanics. While its center-of-mass motion has been investigated intensively, its torsional vibration has only been studied theoretically in limited cases. Here we report the first experimental observation of the torsional vibration of an optically levitated nonspherical nanoparticle in vacuum. We achieve this by utilizing the coupling between the spin angular momentum of photons and the torsional vibration of a nonspherical nanoparticle whose polarizability is a tensor. The torsional vibration frequency can be 1 order of magnitude higher than its center-of-mass motion frequency, which is promising for ground state cooling. We propose a simple yet novel scheme to achieve ground state cooling of its torsional vibration with a linearly polarized Gaussian cavity mode. A levitated nonspherical nanoparticle in vacuum will also be an ultrasensitive nanoscale torsion balance with a torque detection sensitivity on the order of 10(-29) Nm/root Hz pHz under realistic conditions.