Quantum Acoustics

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. 

[1] M. J. Woolley and A. A. Clerk, Phys. Rev. A 87, 063846 (2013).
[2] C. F. Ockeloen-Korppi et al., Phys. Rev. Lett. 117, 140401 (2016).
[3] M. J. Woolley and A. A. Clerk, Phys. Rev. A 89, 063805 (2014).
[4] C. F. Ockeloen-Korppi et al., Nature 556, 478-482 (2018).