New device could help answer fundamental questions about quantum physics
Researchers have developed a new device that can measure and control a nanoparticle trapped in a laser beam with unprecedented sensitivity. The new technology could help scientists study a macroscopic particle's motion with subatomic resolution, a scale governed by the rules of quantum mechanics rather than classical physics.
The researchers from the University of Vienna in Austria and the Delft University of Technology in the Netherlands report their new device in Optica, The Optical Society's journal for high impact research. Although the approach has been used with trapped atoms, the team is the first to use it to precisely measure the motion of an optically trapped nanoparticle made of billions of atoms.
[...] The new method uses a light-guiding nanoscale device called a photonic crystal cavity to monitor the position of a nanoparticle levitating in a traditional optical trap. Optical trapping uses a focused laser beam to exert a force on an object to hold it in place. The technique was recognized by the award of the 2018 Nobel Prize in Physics to pioneer, Arthur Ashkin.
[...] The new device accomplishes a high level of sensitivity by using a long photonic crystal cavity that is narrower than the wavelength of the light. This means that when light enters and travels down the nanoscale cavity, some of it leaks out and forms what is called an evanescent field. The evanescent field changes when an object is placed close to the photonic crystal, which in turn changes how the light propagates through the photonic crystal in a measurable way.
Near-field coupling of a levitated nanoparticle to a photonic crystal cavity (open, DOI: 10.1364/OPTICA.5.001597) (DX)
