Phonon counting and intensity interferometry of a nanomechanical resonator

Justin D. Cohen, Sean M. Meenehan, Gregory S. MacCabe, Simon Gröblacher, Amir H. Safavi-Naeini, Francesco Marsili, Matthew D. Shaw, Oskar Painter  

Nature, 520, pg. 523 (2015)

Abstract
In the publication we perform a Hanbury Brown and Twiss type experiment with phonons (mechanical excitations). We demonstrate how the phonons have different statistical properties depending on how strongly the mechanical oscillator is driven with a laser. The mechanical motion changes from a thermal state to a displaced thermal state, which is very similar to the state of a laser (coherent state). The read-out is done by mapping the mechanical oscillations onto a laser and measure the statistics of the photons - a novel method that paves the way to observe non-classical mechanical behavior in the near future.

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NB: The measurements for this article were done at Caltech.