Scientists have made nanoparticles that spin around each other at a rate of a billion times per second, creating the fastest mechanical rotation in history.
Nanoparticles Spinning A Billion Times Per Second
Nanoparticles are microscopic particles. There is currently an interest in nanoparticle research because of a wide array of potential applications, particularly in electronic, optical and biomedical fields.
Scientists now report fast-spinning particles that can test the limits of physics. Researchers were conducting studies on how light's energy can move nanoparticles and ended up producing record spin frequencies.
Two teams of researchers produced their spinning nanoparticles similarly. They independently achieved the intense spin using levitated optomechanical systems that are extremely isolated from any outside environment. This creates a testing ground for basic fundamentals of physics
Nanoparticles in vacuum spin very fast because there is no air that creates resistance. The atoms will not blow apart until such time the force of the spin overcomes the force that holds them together.
Applications
The first team, which was studying how to use particles levitated by light in a vacuum as torsion balance, created and levitated nanoscale silica dumbbells the size of a virus. Torsion balance is a tool used to measure very weak forces.
The researchers, however, found that when a circularized polarized light is shone into the dumbbell, the latter would spin with the incredible speed of a billion times per second. If the rotations are fast enough, the particles could provide a way to measure the friction of particles against spacetime.
"Levitated optomechanics has great potentials in precision measurements, thermodynamics, macroscopic quantum mechanics and quantum sensing." wrote Tongcang Li, from Purdue University, and colleagues in their study to be published in Physical Review Letters.
The researchers added that levitated nanodumbbell torsion balance offer chance to observe the Casimir torque and investigate the quantum nature of gravity.
The second team arrived at a similar result using silica nanoparticles. They measured the frequency of the spin based on the light that scattered off of the particles.
"Rapidly changing the polarization of the trapping light allows us to extract the pressure-dependent response time of the particle's rotational degree of freedom, study researcher René Reimann, from ETH Zürich, Switzerland and colleagues wrote in their report, also to be published in the journal Physical Review Letters.
Reimann and colleagues said that experiments such as this can help measure the extremes of physics and even mysterious cosmological signals.
