Phonon counting and intensity interferometry of a nanomechanical   resonator
  Using an optical probe along with single photon detection we have performed effective phonon counting measurements of the acoustic emission and absorption processes in a nanomechanical resonator. Applying these measurements in a Hanbury Brown and Twiss set-up, phonon correlations of the nanomechanical resonator are explored from below to above threshold of a parametric instability leading to self-oscillation of the resonator. Discussion of the results in terms of a "phonon laser", and analysis of the sensitivity of the phonon counting technique are presented. 
Justin D. Cohen, Sean M. Meenehan, Gregory S. MacCabe, Simon   Groblacher, Amir H. Safavi-Naeini, Francesco Marsili, Matthe...
quant-ph physics.optics