Together with Prof. Anton Zeilinger and Prof. Markus Aspelmeyer from the University of Vienna, we are pursuing experiments to demonstrate entanglement between quantum optical fields and opto-mechanical structures. Our approach is to use super-mirror material formed from alternating layers of two low loss dielectrics. This technology is capable or producing near perfect mirrors with part per million loss for reflection, and has been used in cavity QED experiments by Kimble at Caltech.
Starting with wafers coated with this mirror material and then using surface micromaching techniques, we have formed integrated opto-mechanical structures, shown below. By placing this device into a high finesse optical cavity, our colleagues in Vienna have been able to demonstrate cooling of the mechanical mode using forces dominated by the fundamental radiation pressure. Along with two other related opto-mechanical experiments, our collaboration reported cooling of the mechanical mode from room temperature to a few kelvin in late 2006 in Nature.
These scanning electron micrographs show our latest opto-mechanical structure fabricated by Jared Hertzberg. The upper image shows a few finished cantilevers formed of a high-stress silicon nitride, 1micron thick film; XeF2 is used to undercut the cantilevers. The disc at the end of each cantilever is a dielectric stack, super-mirror 50 microns in diameter. The lower SEM pic shows the dielectric layers of the super-mirror. These structures have recently shown mechanical resonances from 250kHz to 600kHz, mechanical quality factors as high as 20,000 at 300K, and have formed an optical cavity with finesse of 5,000.