August 12, 2015

Researchers Optically Levitate a Glowing, Nanoscale Diamond

'The researchers show photoluminescence from an optically levitated nano diamond.
Photo by J. Adam Fenster/University of Rochester. '

(August 12, 2015)  Researchers at the University of Rochester have measured for the first time light emitted by photoluminescence from a nanodiamond levitating in free space. In a paper published this week in Optics Letters, they describe how they used a laser to trap nanodiamonds in space, and – using another laser – caused the diamonds to emit light at given frequencies.

The experiment, led by Nick Vamivakas, an assistant professor of optics, demonstrates that it is possible to levitate diamonds as small as 100 nanometers (approximately one-thousandth the diameter of a human hair) in free space, by using a technique known as laser trapping.

"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," said Vamivakas. He said an example of such a system would be an optomechanical resonator.

Vamivakas explained that optomechanical resonators are structures in which the vibrations of the system, in this case the trapped nanodiamond, can be controlled by light. "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."

Possible avenues of interest in the long-term with these nano-optomechanical resonators include the creation of what are known as Schrödinger Cat states (macroscopic, or large-scale, systems that are in two quantum states at once). These resonators could also be used as extremely sensitive sensors of forces – for example, to measure tiny displacements in the positions of metal plates or mirrors in configurations used in microchips and understand friction better on the nanoscale.

Nick Vamivakas and Levi Neukirch in front of their experiment.
Photo by J. Adam Fenster / University of Rochester

"Levitating particles such as these could have advantages over other optomechanical oscillators that exist, as they are not attached to any large structures," Vamivakas explained. "This would mean they are easier to keep cool and it is expected that fragile quantum coherence, essential for these systems to work, will last sufficiently long for experiments to be performed."

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