| mang2004 |
2020-01-19 01:03 |
Ultrasensitive torque detection with an optically levitated nanorotor <}WSYK,zUY
Abstract *}89. kCBF
Torque sensors such as the torsion balance enabled the first determination of the gravitational constant by Henri Cavendish and the discovery of Coulomb’s law. Torque sensors are also widely used in studying small-scale magnetism, the Casimir effect and other applications. Great effort has been made to improve the torque detection sensitivity by nanofabrication and cryogenic cooling. Until now, the most sensitive torque sensor has achieved a remarkable sensitivity of 2.9 × 10−24 N m Hz−1/2 at millikelvin temperatures in a dilution refrigerator. Here, we show a torque sensor reaching sensitivity of (4.2 ± 1.2) × 10−27 N m Hz−1/2 at room temperature. It is created by an optically levitated nanoparticle in vacuum. Our system does not require complex nanofabrication. Moreover, we drive a nanoparticle to rotate at a record high speed beyond 5 GHz (300 billion r.p.m.). Our calculations show that this system will be able to detect the long sought after vacuum friction near a surface under realistic conditions. The optically levitated nanorotor will also have applications in studying nanoscale magnetism and the quantum geometric phase. LKvX~68
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