Present status and future challenges of non-interferometric tests of collapse models

TL;DR

This paper reviews the current state and future challenges of non-interferometric experiments testing collapse models, which question the universality of quantum mechanics at macroscopic scales.

Contribution

It provides a comprehensive overview of existing non-interferometric tests and discusses future experimental directions for challenging collapse models.

Findings

Non-interferometric experiments effectively test collapse models.

Current experiments include cold atoms, optomechanics, X-ray detection, and cosmological observations.

Future experiments aim to further constrain or validate collapse models.

Abstract

The superposition principle is the cornerstone of quantum mechanics, leading to a variety of genuinely quantum effects. Whether the principle applies also to macroscopic systems or, instead, there is a progressive breakdown when moving to larger scales, is a fundamental and still open question. Spontaneous wavefunction collapse models predict the latter option, thus questioning the universality of quantum mechanics. Technological advances allow to challenge collapse models and the quantum superposition principle more and more with a variety of different experiments. Among them, non-interferometric experiments proved to be the most effective in testing these models. We provide an overview of such experiments, including cold atoms, optomechanical systems, X-rays detection, bulk heating as well as comparisons with cosmological observations. We also discuss avenues for future dedicated experiments, which aim at further testing collapse models and the validity of quantum mechanics.