Quantum Radiation Pressure Noise: Exposing the Quantum Mechanics of Optomechanical Interactions

Abstract

The detection of gravitational waves has further motivated the scientists to push horizons for an improved sensitivity sphere of the advanced LIGO. Below 100 Hz, design sensitivity of the advanced LIGO is predicted to be limited by the quantum backaction or the quantum radiation pressure noise (QRPN). In this thesis, I present the experimental progress towards the measurement of the QRPN. This work is in part an effort towards establishing a tabletop test experiment to calibrate the QRPN evasion through various proposed schemes, and further bring to light new nonlinear optomechanical dynamics. The experiment consists of a high optical and mechanical quality microresonator used as a movable end mirror in a high finesse optical cavity. To effectively infer the quantum superposition of the optomechanical interactions, the optomechanical dynamics must be stabilized and the microresonator must be maximally decoupled from the noisy thermal environment. I demonstrate the optical dilution of the Brownian dissipation of the mechani- cal state of the microresonator, by exploiting the optical spring effect of the optomechanical system. I also discuss the pump-probe scheme where two fields are injected into the optomechanical cavity, for enhancing the optomechanical correlations and hence exposing the QRPN. I further demonstrate a new scheme for the optical trapping of the mechanical state. Here we exploited the polarization dependent frequency shift effects of the birefringent microresonator test mass. Given the development towards the ability to manipulate the frequency shifts between the two polarizations of the input field, the technique may find potential use towards achieving the self stabilizing optomechanics to trap the macroscopic test mass in the desired mechanical state. In the appendices, I also discussed the computational project to investigate the laser cooling of a two level atomic state by the stimulated emission. Given the effective control over the heat exchange between the atom and the entropy reservoir laser field, this technique serves potential towards the laser cooling of the macroscopic mechanical systems.