Quantum noise interference as a route to ground state cooling in cavity electromechanics

We present a theoretical analysis of a novel cavity electromechanical (or optomechanical) system where a mechanical resonator directly modulates the damping rate $\kappa$ of a driven microwave (or optical) cavity. We show that due to a destructive interference of quantum noise, the driven cavity can effectively act like a zero-temperature bath {\it irrespective} of the ratio $\kappa / \omega_M$, where $\omega_M$ is the mechanical frequency. This scheme thus allows one to cool the mechanical resonator to its ground state without requiring the cavity to be in the so-called good cavity limit $\kappa \ll \omega_M$. This behavior is in sharp contrast to the more common setup with a parametric coupling (where the mechanics modulates the frequency of the cavity); there, ground state cooling is only possible in the good cavity limit [1,2]. We also show that this system can be used to perform quantum-limited position measurements. The system described here could be implemented directly using setups similar to those used in recent experiments in cavity electromechanics [3]. \\[4pt] [1]~F. Marquardt \textit{et al.}, Phys.\ Rev.Lett.\ \textbf{99}, 093902 (2007).\\[0pt] [2]~I. Wilson-Rae \textit{et al.}, Phys.Rev.\ Lett.\ \textbf{99}, 093901 (2007).\\[0pt] [3]~J. D. Teufel \textit{et al.}, Phys.\ Rev.Lett.\ \textbf{101}, 197203 (2008).