EUGENE, Ore. -- (Nov. 15, 2012) -- Using tiny radiation pressure forces -- generated each time light is reflected off a surface -- University of Oregon physicists converted an optical field, or signal, from one color to another. Aided by a "dark mode," the conversion occurs through the coupling between light and a mechanical oscillator, without interruption by thermal mechanical vibrations.
In the quest for networking quantum systems and eventually building a quantum Internet -- where photons carry information -- color conversion will be crucial, said co-author Hailin Wang, a member of the Oregon Center for Optics and a professor in the UO physics department. Getting different quantum systems, or nodes, to talk to each other is a major challenge since these systems communicate with photons of distinct wavelength or color. "This is not unlike getting a PC to talk to a Mac, but it involves a quite different process," he said.
"Optomechanical systems can be used to store light and change its color -- operations that are important for a quantum network," said co-author Chunhua Dong, a postdoctoral research associate in Wang's lab.
In a paper appearing Nov. 16 online via Science Express in advance of publication in the journal Science, the Oregon group describes the discovery. The group's experiment couples the radiation pressure force that is generated by light circulating inside a glass microsphere -- about the size of a human hair -- to the mechanical breathing motion of the microsphere. One can change the color of a light pulse by first exciting a mechanical vibration through the optomechanical coupling, and then using the vibration to generate a new light pulse at the desired color.
Making the conversion currently is limited by thermal mechanical motion -- only at temperatures approaching absolute zero can such an approach be useful for quantum applications. As an example of the challenge, the researchers sa
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University of Oregon