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Sunday, 26 January 2020

World's fastest rotating object to study vacuum friction

The fastest-spinning object ever created is a nano-scale rotor made from silica at Purdue University. This image of the rotor at rest was created using a scanning electron microscope. For scale, the yellow bar in the image is 200 nanometers. (Purdue University photo/Jaehoon Bang)

In 2018, a team from the U.S. and another from Switzerland, working independently, created the world's fastest rotating objects , which are helping to study the true nature of the quantum vacuum .

These studies now promise to be even more accurate, as Jonghoon Ahn and his colleagues at Purdue University in the U.S. upgraded their nanorotor, which now spins an impressive 300 billion RPM (revolutions per minute), which is a bit million times faster than a dentist's drill.

The rotor, measuring 200 nanometers (0.2 micrometer), consists of two silica particles joined by the center, which gives it a shape that resembles a dumbbell.

It does not need an axis because the nanoparticle is levitated in a vacuum by optical tweezers. Then, another laser is used to make the particle spin, transmitting torque by the pressure of light radiation , the same principle that drives solar sails in space.

Polarized light induced by the laser transmits a torque that makes the nanorotor spin.

As it receives torque from the light, whose power can be carefully controlled, the rotor itself becomes an extremely sensitive torque detector - in fact, the most sensitive one ever manufactured, being 600 to 700 times better than its predecessors.

This will allow it to continue to be used to explore the mysteries of the vacuum. Contrary to what you can imagine, the vacuum is far from being something empty, being full of virtual particles that emerge and decay all the time. With its sensitivity, this new version of the fastest object in the world will allow to detect and measure the torque of these emerging particles.

In other words, it will be used to measure vacuum-induced friction.

The torque nanodetector can also be used to measure related effects, including the Casimir effect and nanoscale magnetism, phenomena essential for the development of nanoscale devices, such as NEMS , nanomachines and nanorobots.


Article: Ultrasensitive torque detection with an optically levitated nanorotor

Authors: Jonghoon Ahn, Zhujing Xu, Jaehoon Bang, Peng Ju, Xingyu Gao, Tongcang Li

Magazine: Nature Nanotechnology

DOI: 10.1038 / s41565-019-0605-9

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