Researchers working at the University of Rochester have successfully harnessed the power of laser light to levitate nanodiamond crystals, using a technique called laser trapping. One potential application of this discovery, It is thought, could lie in the production of Schrödinger cat states.
The team firstly directed a single laser towards the nanodiamond crystal, allowing it to become suspended in space. A second laser was then aimed at this levitating nanodiamond, resulting in the emission of light of varying frequencies, the release of which was subsequently gauged. The resulting photoluminescence released was caused by defects within the nanodiamond’s structure.
However, catching the diamond was tricky to begin with. One of the graduate student working on the project, Levi Neukirch, said he sprayed aerosolized nanodiamonds into the chamber to try to capture the diamonds. Sometimes it would take a matter of minutes, other times it could take up to “half an hour.”
This photoluminescence is caused by the substitution of carbon atoms for nitrogen (nitrogen vacancies). Photons of laser light, from the second laser source, are absorbed by the defects, which excites electrons from a low energy level to a higher one. Once this occurs, the electrons then relax and release their own photons, a well-known process, called optical pumping.
The lead scientist, Assistant Professor of Quantum Optics and Quantum Physics, Nick Vamivakas, suggested possible exciting applications for the experiment, according to the University of Rochester’s own website:
“Now that we have shown we can levitate nanodiamonds and measure photoluminescence from defects inside the diamonds, we can start considering systems that could have applications in the field of quantum information and computing.”
One such application, which Vamivakas suggested himself, was the implementation of optomechanical resonators. These devices can be used to harness the vibration of the nanodiamond, which is tightly regulated by the laser light. Although the group has yet to investigate this particular application, Vamivakas states that such a structure could “… encode information in the vibrations of the diamonds,” the information of which could then be “read” using the resultant emitted light.
These levitating diamond could also be harnessed to institute Schrödinger’s cat states. Schrödinger’s cat was a famous thought experiment based around quantum mechanics. Schrödinger was a famous Austrian scientist who considered that observation was key to determining the fate of macroscopic system. He proposed a hypothetical experiment, where he placed a cat into an opaque box. Hooked to the box was a Geiger counter, filled with a small amount of radioactive material. Once this radioactive material decayed, this was detected by the counter, which then smashed a vial of poison inside the box. As the researcher could not see into the box, the fate of the cat was undetermined and, he proposed, the cat existed in two states simultaneously (both dead and alive).
Here, the group propose that these optomechanical resonators could be harnessed to create macroscopic systems that exist in two states simultaneously.
The team also suggest its application in small-scale architecture, such as microchip hardware. The devices could also be used to understand frictional forces on a microscopic scale, as well as detect small changes in the force applied to mechanical structures of nanoscale systems. Since the nanodiamonds are levitating, and are not attached to any other structures, Vamivakas suggests it would be easier to keep them cooler and would “… last sufficiently long for experiments to be performed.”
Although similar studies have been performed, this is the first time that diamonds have been levitated. This work, and others like it, could herald new understanding of Schrödinger cat states, and allow the development of sophisticated quantum computers.
By: James Fenner