Optically Levitated Nanodumbbell Could Further Study of Quantum Mechanics

Using levitated optomechanics, a man-made rotor has been created that can spin at 60 billion revolutions per minute. Such ultrafast rotation could be used to study material properties and probe vacuum friction.

Researchers from Purdue University synthesized nanodumbbells from silica and optically levitated them in high vacuum using a laser. When the laser beam was linear, the dumbbell vibrated; when the beam was circular, the dumbbell spun.

Tongcang Li (left) and Jonghoon Ahn have levitated a nanoparticle in vacuum and driven it to rotate at high speed, which they hope will help them study the properties of vacuum and quantum mechanics. Courtesy of Purdue University/Vincent Walter.

Using a linearly polarized laser, researchers observed the torsional vibration of the optically levitated nanodumbbell. The levitated nanodumbbell torsion balance — a novel analog of the Cavendish torsion balance — allowed researchers to observe the Casimir torque and probe the quantum nature of gravity.

“People say that there is nothing in vacuum, but in physics, we know it’s not really empty," said professor Tongcang Li. "There are a lot of virtual particles which may stay for a short time and then disappear. We want to figure out what’s really going on there, and that’s why we want to make the most sensitive torsion balance.”

Researchers have created the fastest man-made rotor in the world by spinning a nanodumbbell with a circularly polarized laser. Courtesy of Purdue University/Janghoon Ahn.

Using a circularly polarized laser, researchers drove a 170-nm-diameter nanodumbbell to rotate beyond 1 GHz, which they believe to be the fastest nanomechanical rotor realized to date. Researchers believe that smaller silica nanodumbbells could sustain higher rotation frequencies.

The team’s observations could help advance knowledge of vacuum friction and gravity. Understanding these mechanisms is an essential goal for the modern generation of physics, Li said.

“This study has many applications, including material science. We can study the extreme conditions different materials can survive in,” he said.

The research was published in Physical Review Letters (doi:10.1103/PhysRevLett.121.033603).

Purdue University researchers have created what they believe to be the fastest man-made rotor in the world. At more than 60 billion revolutions per minute, this machine is more than 100,000 times faster than a high-speed dental drill. Courtesy of Purdue University.