Light-Sound Coupling Could Aid Quantum Devices

Researchers at the University of Oxford, Imperial College London and the National Physics Laboratory, U.K., have demonstrated strong coupling between light and high-frequency acoustic vibrations in a silica microresonator. The team believes the work—which achieves a long-standing goal in optomechanics—could open interesting prospects in exploiting light–sound coupling for technology development in both the classical and quantum domains.

The work involves the well-known nonlinear phenomenon of Brillouin scattering, first described in the 1920s by the French scientist Leon Brillouin. Essentially, Brillouin scattering involves the interaction of photons of light with phonons of thermal or acoustic energy in the material in which the light propagates; that interaction, in turn, produces scattered light at a characteristic frequency shift. In the so-called Stokes process of Brillouin scattering, the frequency of the scattered light is downshifted relative to the pump light; the much weaker anti-Stokes process results in scattered light at a higher frequency than the pump light.

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