Fig. 1: Overview of the experiment.
From: High purity two-dimensional levitated mechanical oscillator
a Simplified scheme of the experimental setup. OI: optic isolator, WP: wave plate, PL: phase locking photodiode, AOM: acousto-optic modulator, EOM: electro-optic modulator, PDH: Pound-Drever-Hall detection, LO: local oscillator, BHD: balanced heterodyne detection, ADC: analog-to-digital converter. b Power spectral density (PSD) of the heterodyne signal for a detuning Δ/2π = − 250 kHz. We show the anti-Stokes sideband, and we report in the abscissa (ΩLO − ω)/2π. The spectrum is normalized to the measured shot noise, which is then subtracted (the dark noise, which is ~ 10 dB lower than the shot noise, is preliminarily subtracted from all spectra). The three resonance peaks corresponding to the X, Y, and Z modes are identified. The inset shows the scheme of a plane orthogonal to the tweezer axis, where Y denotes the tweezer polarization axis, and X its orthogonal direction.
