# Testing collapse models with levitated nanoparticles: the detection challenge

## TL;DR

This paper evaluates various detection methods for levitated nanoparticles in cryogenic vacuum to test spontaneous collapse models, emphasizing the importance of ultra-low pressure and minimal power detection.

## Contribution

It compares three detection techniques—optical cavity, optical tweezer, and electrical readout—for their effectiveness in noninterferometric tests of collapse models.

## Key findings

- Optical cavity detection offers high sensitivity but is technically complex.
- Electrical readout provides a simpler setup with lower power requirements.
- Achieving ultralow residual pressure is critical for successful testing.

## Abstract

We consider a nanoparticle levitated in a Paul trap in ultrahigh cryogenic vacuum, and look for the conditions which allow for a stringent noninterferometric test of spontaneous collapse models. In particular we compare different possible techniques to detect the particle motion. Key conditions which need to be achieved are extremely low residual pressure and the ability to detect the particle at ultralow power. We compare three different detection approaches based respectively on a optical cavity, optical tweezer and a electrical readout, and for each one we assess advantages, drawbacks and technical challenges.