Fig. 3: Exciton-phonon coupling strength.
From: A single-photon emitter coupled to a phononic-crystal resonator in the resolved-sideband regime
a Phonon-energy-ladder diagram for a driven two-level system. The excitation laser dresses the two-level system. The interaction between the two systems is strongest when the dressed-state splitting (effective Rabi frequency, \({\Omega }_{{{{\rm{R}}}}}^{{{{\rm{eff}}}}}/2\pi\)) is equal to the sideband separation (mechanical frequency, Ωm/2π). b Simulated mechanical-noise sensitivity in the unresolved-sideband regime, given by the derivative of the QD counts. c Simulated mechanical-noise sensitivity of the current device. ∫Snn(fm)df is the integrated noise power of the mechanical resonace. The condition of \({\Omega }_{{{{\rm{R}}}}}^{{{{\rm{eff}}}}}={\Omega }_{{{{\rm{m}}}}}\) is highlighted by the dashed black line. d QD linewidth at elevated excitation power (ΩR = 4ΓR) as used in the thermal-motion measurement. e Auto-correlation measurements at two different detunings (i) and (ii) (see dashed lines in (d) and stars in (c)). The larger detuning corresponds to \({\Omega }_{{{{\rm{R}}}}}^{{{{\rm{eff}}}}}={\Omega }_{{{{\rm{m}}}}}\). f Noise-power spectra obtained from (e) reveal the mechanical peak only for optimal effective Rabi frequency (detuning (ii), green line). g Integrated mechanical noise in dependence on the laser detuning. An exciton-phonon coupling rate of gep/2π = 2.9 MHz is extracted from a model-fit to the data. Data and fit errors are given by one standard deviation. h Zoom-in of a 14-h auto-correlation measurement, showing mechanical oscillations. Dashed lines show the expected noise peaks, spaced by Tm = 2π/Ωm = 0.68ns.
