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 re-port the first experimental observation of the torsional vibration of an optically levitated non spherical nanoparticle in vacuum. We achieve this by utilizing the coupling between the spin angular momentum of photons and the torsional vibration of a non spherical nanoparticle whose polarizability is a tensor. The torsional vibration frequency can be one 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 nano-diamond with building-in Nitrogen-vacancy centers is also suit-able for generating multipartite quantum entanglement and simulating many-body spins models. We will briefly discuss it in the last of the talk.

Reference:  Phys. Rev. Lett. 117, 123604 (2016), arXiv:1611.05599

尹璋琦, 1999至2009年在西安交通大学获得物理学学士, 硕士和博士学位, 曾在美国密西根大学、中国科学技术大学和中科院武汉物理数学研究所等地从事科研工作。从2012年起, 他在清华大学交叉信息研究院量子信息中心任助理研究员。研究兴趣包括量子信息的物理实现方案、光力学系统、量子信息科学基础理论等。