Testing collapse models with levitated nanoparticles: Detection challenge

Collapse models, proposed to explain the absence of quantum superpositions at macroscopic scales, generically predict the existence of random forces on a massive object. Here, detection of levitated particle motion is explored though three different approaches based on an optical cavity, an optical tweezer, and an electrical readout exploiting a SQUID. These approaches are analyzed and compared, and the advantages, drawbacks, and technical challenges are assessed.