Quantum properties of glass micromechanical oscillator are controlled by light
Lausanne, Switzerland--Physicists at the Ecole Polytechnique Fédérale de Lausanne (EPFL), who have for years been making ultrahigh-quality microring resonators for various purposes, have created one that is large enough (30 microns in diameter) to be seen with the naked eye but at the same time can be controlled by light at the level where quantum mechanics governs its behavior.1 The glass microtoroid consists of about 1014 atoms and forms a micromechanical oscillator with vibrations that can be quantum-coherently coupled to optical photons, at least when the device is cooled to less than 1 K.
Under the direction of Tobias Kippenberg, the team injected a laser into a thin optical fiber placed near enough to the toroid that light was evanescently coupled into the toroid. The light launched into the ring reduces vibratory motion by a factor of a hundred times, thus cooling the ring even more and bringing it very close to its quantum ground state. More importantly, the interaction between light and the movement of the oscillator can be made so strong that the two form an intimate connection: A small excitation in the form of a light pulse can be fully transformed into a small vibration and back again.
For the first time, this transformation between light and motion was made to occur within a time that is short enough so that the quantum properties of the original light pulse are not lost in the process through decoherence. By outpacing decoherence, these results demonstrate the possibility of controlling the quantum properties of an object’s motion. It also provides a way to see the peculiar predictions of quantum mechanics at play in man-made objects.
Mechanical vibrations can be coupled to quantum systems of completely different natures (such as electric currents), as well as to light. They could therefore be used to ‘translate’ quantum information between those systems and light signals. This is especially beneficial as it allows to transport quantum information over large distances in optical fibers. These micromechanical oscillators can thus become quantum transducers, as well as serve in microwave-to-optical quantum links.
REFERENCE:
1. Verhagen et al., Nature, Published online 01 Feb. 2012; doi: 10.1038/nature10787
John Wallace | Senior Technical Editor (1998-2022)
John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.