Ultranarrow-linewidth levitated nano-oscillator for testing dissipative wave-function collapse

This work measures dissipation affecting a nano-particle levitated in a Paul trap in high vacuum. By evaluating the energy power spectral density of the resulting low frequency harmonic oscillator, the authors spectrally resolve an ultra-narrow linewidth of 80 {}Hz. These measurements are then used to place bounds on two wavefunctions collapse models in their dissipative variants, namely the continuous spontaneous localization and the Di\'osi-Penrose model