Recent efforts led by Justin Cohen, Sean Meenehan, and Greg MacCabe of the Painter Lab, in colloboration with Matt Shaw and Francesco Masilli from JPL, have realized efficient counting of individual phonon emission and absorption events from a micro-mechanical resonator. The phonon counting technique relies upon the faithful mapping of phonon processes to the emission of individual photons, which can then be counted one-by-one using single-photon detectors.
a, Phonon count rate (blue: left-hand vertical axis) and inferred phonon occupancy 〈n〉 (red: right-hand vertical axis) as a function of intracavity photon number nc for Δ = −ωm. Dashed lines indicate points below (blue), at (green) and above (magenta) threshold. b, Noise power spectral densities (NPSD) corresponding to the dashed lines in a. The small satellite peaks in the thermal emission background of the above-threshold spectrum correspond to beating of the phonon laser line with low-frequency modes of the nanobeam structure. c, Phase plots of the in-phase (I) and in-quadrature (Q) amplitudes of the optical heterodyne signal for each of the dashed lines in a, acquired in a 36 MHz span around 5.588 GHz over a 60 s time interval.
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