The field of optomechanics, in particular the cooling of small mechanical oscillators, is currently one of the most exciting and rapidly growing areas of physics. An important question is whether one can not only reach, but also operate these devices in the quantum regime. In addition to the fundamental interest, there are promising possibilities for highly sensitive measurements of weak forces at the quantum limit (in other words with a displacement limited only by the width of the ground state of the mechanical oscillator). It will also have applications for generating entanglement between the light field and the mechanical modes. We are currently exploring cavity cooling of nanoscale polarisable particles. Such large particles (in the 100 nm size range) interact strongly with a cavity field, allowing both trapping and cooling by the same field. Since in these cooling schemes no internal resonance is involved, no detailed knowledge of the internal structure of the particle is required. Significantly, unlike usual cavity optomechanics schemes, where the object is physically connected to the environment, the nanoparticle to be cooled is held in a conservative potential so is well isolated from the environment. This confers unique advantages, over conventional optomechanical schemes, in relation to the ultimate objective of cooling to the ground state.

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