Zhangqi Yin, Assistant Research Fellow in CQI, cooperating with Purdue University, made the first experimental observation of torsional motion of a nanoparticle levitated in a vacuum, which represents a very sensitive torque detector. The paper “Torsional optomechanics of a levitated nonspherical nanoparticle” was published in Physical Review Letters as an Editor’s Suggestion.  

Zhangqi Yin, in collaboration with Tongcang Li’s group of Purdue University, had levitated a tiny nanodiamond particle with a laser in a vacuum chamber, using the technique for the first time to detect and measure its "torsional vibration," an advance that could bring new types of sensors and studies in quantum mechanics.

The paper discusses the detection of torsional vibration, a proposal to use the technique for torque sensing and how to achieve torsional "ground state cooling," which could aid efforts to study quantum theory and realize potential applications in quantum information processing and high-precision measurement for sensors.

This cooling reduces "noise" caused by torsional vibration, making it possible to precisely measure torque and probe the relationships between motion and electron "spin." Electrons can be thought of as having two distinct spin states, "up" or "down," and this phenomenon might be used in future quantum simulations.

Link to the paper:

http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.117.123604

(By Shuang Hao)