Scientists Can Levitate Nanodiamonds in a Vacuum Using Laser Light

Illustration for article titled Scientists Can Levitate Nanodiamonds in a Vacuum Using Laser Light

A team of researchers from the University of Rochester has managed to levitate nanodiamonds in a vacuum using laser light for the first time—which could provide a new breed of microscopic sensors.


It’s not the first time scientists have used laser light to levitate nanoparticles. But what’s different this time is that the nanodiamonds are optically active: they contain nitrogen-vacancies that can emit light, which means they can actually do something while they float in space.

The scientists first performed experiments levitating the nanodiamonds in air, as shown above, before tweaking their set-up so that they could do the same in a vacuum. In air, the microscopic particles are bombarded with molecules which makes it hard to keep them in place. In a vacuum, those effects are removed. “This allows us to exert mechanical control over them,” explains Levi Neukirch, the lead researcher behind the study, to PhysOrg. The research is published in Nature Photonics.

By constantly measuring the tiny movements of the particles as it sits in the vacuum supported by the laser, the team can adjust the intensity of the light to ensure it stays in place, moving by only tiny amounts. One laser is used to excite the nitrogen-vacancies which in turn emit light; that provides the researchers with the information required to tune a second laser which traps the nanodiamond, levitating it in the vacuum.

While the work is progressing well, the researchers hope to reduce the oscillations of the nanodiamonds to virtually nothing—the so-called ground state. But right now, that involves using temperatures and pressures that destroy the nanodiamonds.

Still, the systems should prove useful regardless. The relative lack of movement means that the nanodimaonds could be used to measure extremely tiny forces or torques: even tiny forces will moves the particles very slightly, and the emitted light from the nitrogen vacancies should provides a means of measuring them. It’s like a tiny set of weighing scales—one that should only get more accurate with time.

[published in Nature Photonics via PhysOrg]

Image by J. Adam Fenster/University of Rochester




Laser based atomic traps have been used to be used to suspend and supercool larger and larger groups of atoms and molecules for about 30 to 40 years now so I’m not surprised they’ve got them to sufficient strength to levitate something about 10 nanometers in size, smaller than most viruses.

I don’t know what kinds of practical uses this instrument would have but, perhaps, it might have application in giving us precise measurements of the gravitational force on the submicroscopic scale—something which has been notoriously hard for us to do because gravity is so weak and the scales are so tiny.

And why does measuring gravity so accurately at such a tiny scale matter? String theory. String theory predicts that gravitational energy leaks away into higher, but compactified, dimensions at small scales. Our measurements of gravity at these scales should notice gravity becoming somewhat stronger because the loss of energy at such a scale is smaller than over large volumes of space-time.

This is one of the few predictions made by string theory that we can actually test in a reasonable way.

I think this instrument, with its highly precise control of laser brightness and focus, might be useful in that search.