Non-interferometric test of the continuous spontaneous localization model based on rotational optomechanics

Abstract

The continuous spontaneous localization (CSL) model is the best known and studied among collapse models, which modify quantum mechanics and identify the fundamental reasons behind the unobservability of quantum superpositions at the macroscopic scale. Albeit several tests were performed during the last decade, up to date the CSL parameter space still exhibits a vast unexplored region. Here, we study and propose an unattempted non-interferometric test aimed to fill this gap. We show that the angular momentum diffusion predicted by CSL heavily constrains the parametric values of the model when applied to a macroscopic object.

Quantum enhanced estimation of diffusion

“…3 for the position, momentum, and optimal quadratures. For position or momentum measurements with up to 10 dB squeezing the bounds are competive across 10 −8 -10 −5 m, below 10 −8 m X-ray emission data begins to provide a tighter bound [78] while above 10 −5 m LISA Pathfinder data is tighter [16,18]. Additional squeezing can of course further reduce the undertainty, with 20 dB of squeezing sufficient to match the theoretical minimum collapse rate to above 10 −7 m. This would include testing the original parameters suggested by Ghirardi et al [15].…”

“…Mechanical systems have been used to bound the strength of such diffusive effects. Examples include gravitational-wave detectors [16], the LISA pathfinder experiment [16][17][18], ultracold cantilevers [19], and trapped ions [20]. Proposals for future experiments which could probe collapse models and further study macroscopic quantum states include the generation of macroscopic superpositions [21][22][23][24][25][26] and the space-based MAQRO mission [27,28] which formed a key focus of a recent ESA feasibility study [29].…”

Testing collapse models with levitated nanoparticles: Detection challenge

“…For simplicity we will consider a spherical nanoparticle, although comparable results could be achieved by other geometries [24]. We will take SiO 2 as standard material.…”

“…On top of that, the noise field associated with the collapse implies a violation of the energy conservation. So called noninterferometric tests have been arXiv:1903.08492v1 [quant-ph] 20 Mar 2019 proposed to look for these effects, which include spontaneous emission of x-rays [11,12], force noise in mechanical systems [13][14][15][16][17][18][19][20][21][22][23][24] and spontaneous heating of bulk matter [25] or ultracold atoms [26,27]. At present, noninterferometric tests set by far the strongest bound on CSL parameters, which are summarized in Fig.…”

“…In this approach, one looks for the universal force noise which is predicted to be induced by CSL in any massive mechanical system. So far, experiments based on ultracold cantilevers [19,20] and gravitational wave detectors [21][22][23][24] are setting the strongest bounds. It has been suggested that levitated nano or microparticles would be a nearly ideal platform to perform more sensitive tests [28,29].…”