An experimental setup for quantum optomechanics

In the last few years cavity optomechanics experiments have achieved the significant progress of the preparation and observation of macroscopic me- chanical oscillators in non-classical states. An indicator of the oscillator non-classical proprieties is important also for applications to quantum tech- nologies. In this work, we compare two procedures minimizing the necessity of system calibrations. As first result we compare the homodyne spectra with the measurement of the motional sideband asymmetry in heterodyne spectra. Moreover, we describe and discuss a method to control the probe detuning, that is a crucial parameter for the accuracy of the latter, intrin- sically superior procedure. From it we can use the sidebands asymmetry as indicator of the quantumness of the mechanical oscillator, which is originated by the non-commutativity between the oscillator ladder operators. Starting from it the sidebands assume a peculiar shape when a parametric modula- tion is applied on a oscillator embedded in an optical cavity. A parametric effect is originated by a suitable combination of optical fields. The asymme- try shape is related to the modified system dynamics, while the asymmetric features reveal and quantify the quantum component of the squeezed oscilla- tor motion. The results show that it is possible to use the spectral shape of motional sidebands as a signature of a quantum mechanical squeezed state, without the necessity of absolute calibrations, in particular in the regime where residual fluctuations in the squeezed quadrature are reduced below the zero-point level.