Optomechanical devices in the quantum regime

This thesis explores the possibility of controlling the quantum states of high frequency mechanical resonators using infra-red laser pulses. Chapter 1 gives an overview of quantum technologies based on mechanical resonators relevant for this thesis. Chapter 2 provides the basics of the theoretical background of optomechanics. The Hamiltonian that describes the interaction between the moving mirror and electromagnetic waves will be described. The second part of the chapter will deal with methods borrowed from quantum optics and used to demonstrate non-classical behaviour of a mechanical resonator. Chapter 3 presents a physical implementation of optomechanics Hamiltonian in form of silicon nanobeam devices. Additional hardware that needs to be integrated with optomechanical devices in order to perform experiments will be described. This includes optical waveguides and fibers used for coupling light into the cavity. We will start the discussion on how effects beyond simple optomechanics model impact these devices. Chapter 4 describes methods used to microfabricate nanobeam devices on a chip. This chapter aims to give tips and hits toward the successful fabrication of optomechanical devices. Chapter 5 presents the results of an experiment demonstrating non-classical behaviour of a single optomechanical device. We will use a heralding scheme to prepare the nonclassical state of mechanical resonator and use optical detection to confirm its nonclassicality. Chapter 6 describes the measurement of Bell inequality between two optical and two mechanicalmodes. Chapter 7 is the conclusion chapter, where I discuss the results of experiments presented, aswell the potential directions of future experiments and howcontrol over quantumstate of mechanical resonators can be improved.