Acoustics is the study of the propagation of mechanical waves in matter. This can refer to the vibrations of bars or plates, or waves propagating in bulk or at a surface. In any case, one can identify modes of vibration and the study of these normal modes at the level of their quantum zero-point fluctuations has been termed quantum acoustics. I will provide an introduction to this field and then describe recent work on the proposal and realisation of the quantum back-action evading measurement [1,2] and quantum entanglement [3,4] of the motion of massive objects. The former has implications in precision metrology, while the latter has potential implications for the foundations of quantum mechanics and quantum gravity.
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