Narrowing the Parameter Space of Collapse Models with Ultracold Layered Force Sensors

A. Vinante, M. Carlesso, A. Bassi, A. Chiasera, S. Varas, P. Falferi, B. Margesin, R. Mezzena, H. Ulbricht

Research output: Contribution to journalArticlepeer-review

38 Citations (Scopus)
21 Downloads (Pure)


Despite the unquestionable empirical success of quantum theory, witnessed by the recent uprising of quantum technologies, the debate on how to reconcile the theory with the macroscopic classical world is still open. Spontaneous collapse models are one of the few testable solutions so far proposed. In particular, the continuous spontaneous localization (CSL) model has become subject of intense experimental research. Experiments looking for the universal force noise predicted by CSL in ultrasensitive mechanical resonators have recently set the strongest unambiguous bounds on CSL. Further improving these experiments by direct reduction of mechanical noise is technically challenging. Here, we implement a recently proposed alternative strategy that aims at enhancing the CSL noise by exploiting a multilayer test mass attached on a high quality factor microcantilever. The test mass is specifically designed to enhance the effect of CSL noise at the characteristic length rc=10-7 m. The measurements are in good agreement with pure thermal motion for temperatures down to 100 mK. From the absence of excess noise, we infer a new bound on the collapse rate at the characteristic length rc=10-7 m, which improves over previous mechanical experiments by more than 1 order of magnitude. Our results explicitly challenge a well-motivated region of the CSL parameter space proposed by Adler.

Original languageEnglish
Article number100404
JournalPhysical Review Letters
Issue number10
Publication statusPublished - 03 Sept 2020
Externally publishedYes

Bibliographical note

Funding Information:
We gratefully thank S. L. Adler for many stimulating discussions, and N. Bazzanella for technical help. A. B. acknowledges hospitality from the Institute for Advanced Study, Princeton, where part of this work was done. We acknowledge financial support from the EU H2020 FET project TEQ (Grant No. 766900), the Leverhulme Trust (RPG-2016-046), the COST Action QTSpace (CA15220), INFN, and the Foundational Questions Institute (FQXi).

Publisher Copyright:
© 2020 American Physical Society.

ASJC Scopus subject areas

  • General Physics and Astronomy


Dive into the research topics of 'Narrowing the Parameter Space of Collapse Models with Ultracold Layered Force Sensors'. Together they form a unique fingerprint.

Cite this