# An ultra-narrow line width levitated nano-oscillator for testing dissipative wavefunction collapse

## TL;DR

This paper reports the measurement of an ultra-narrow line width levitated nano-oscillator, enabling new tests of dissipative wavefunction collapse models and advancing quantum mechanics research at macroscopic scales.

## Contribution

First direct measurement of an ultra-narrow line width levitated nano-oscillator in high vacuum, demonstrating its potential for fundamental physics tests.

## Key findings

- Line width of $81\, ext{μHz}$ limited by residual gas pressure
- Achieved high mechanical quality factor ($Q \,\sim 10^{12}$)
- Set new bounds on dissipative wavefunction collapse models

## Abstract

Levitated nano-oscillators are seen as promising platforms for testing fundamental physics and testing quantum mechanics in a new high mass regime. Levitation allows extreme isolation from the environment, reducing the decoherence processes that are crucial for these sensitive experiments. A fundamental property of any oscillator is its line width and mechanical quality factor, Q. Narrow line widths in the microHertz regime and mechanical Q's as high as $10^{12}$ have been predicted for levitated systems, but to date, the poor stability of these oscillators over long periods have prevented direct measurement in high vacuum. Here we report on the measurement of an ultra-narrow line width levitated nano-oscillator, whose line width of $81\pm\,23\,\mu$Hz is only limited by residual gas pressure at high vacuum. This narrow line width allows us to put new experimental bounds on dissipative models of wavefunction collapse including continuous spontaneous localisation and Di\'{o}si-Penrose and illustrates its utility for future precision experiments that aim to test the macroscopic limits of quantum mechanics.