Creating and verifying a quantum superposition in an optomechanical system

Full text: Micro-optomechanical systems have become increasingly important in the study of quantum effects in relatively massive systems. Here we review the experiment as proposed by Marshall et al. (2003) which aims to demonstrate a quantum superposition of a mesoscopic cantilever. We analyze in detail the effects of finite temperature on the interpretation of the experiment, and obtain a lower bound on the degree of non-classicality of the cantilever. Although it is possible to measure the quantum decoherence time when starting from finite temperature, an unambiguous demonstration of a quantum superposition requires the mechanical resonator to be in or near the ground state. We also calculate the rate of environmentally induced decoherence and provide a rough estimate of the gravitationally induced collapse as proposed by R. Penrose and L. Diosi. (author)