For the first time, scientists used light to levitate a diamond in free space.
To catch the tiny diamonds in space, scientists sprayed an aerosol that contained dissolved nanodiamonds into a 10-inch wide chamber. The diamonds were attracted to the laser’s focus point, which caused them to drift directly into its light path.
"It takes a couple of squirts, and in a few minutes we have a trapped nanodiamond," Graduate student Levi Neukirch said about the experiment. "Other times I can be here for half an hour before any diamond gets caught. Once a diamond wanders into the trap, we can hold it for hours."
The nanodiamonds were as small as 100 nanometers in length, approximately one-thousandth the diameter of a human hair. The feat, captured on camera, may one day lead to applications in quantum information and computing.
"We are yet to explore this, but in theory we could encode information in the vibrations of the diamonds and extract it using the light they emit," Nick Vamivakas, an assistant professor of optics who led the experiment, said in a press release.
The nanodiamonds emitted light due to photoluminescence. Defects inside the diamonds allowed them to absorb photons from the second laser in the experiment. Absorbing these particles excited the diamond and changed its spin. Once the diamond relaxed, it emitted other photons in a process called optical pumping.
While using lasers to trap ions is a well-known practice in physics, nanodiamonds had never been levitated before.
"Levitating particles such as these could have advantages over other optomechanical oscillators that exist, as they are not attached to any large structures," Vamivakas said, adding that they could be used to create Schrödinger Cat states and sensors to measure displacements between metal plates or mirrors in nanoscale objects like microchips.