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

Area of Science:

• Quantum mechanics and its foundations
• Experimental physics
• Condensed matter physics

Background:

• Quantum theory's success contrasts with its macroscopic interpretation challenges.
• Spontaneous collapse models offer testable solutions, with the continuous spontaneous localization (CSL) model being a key focus.
• Previous experiments using ultrasensitive mechanical resonators set bounds on CSL but face technical noise limitations.

Purpose of the Study:

• To implement an alternative strategy for enhancing CSL noise.
• To test CSL model predictions at a characteristic length of 10⁻⁷ m.
• To derive new bounds on the CSL collapse rate.

Main Methods:

• Utilizing a multilayer test mass attached to a high-quality factor microcantilever.
• Designing the test mass to amplify the CSL noise effect.
• Conducting measurements at temperatures as low as 100 mK.
• Analyzing for excess noise beyond thermal motion.

Main Results:

• Measurements showed good agreement with pure thermal motion down to 100 mK.
• Absence of excess noise allowed inference of new bounds on the CSL collapse rate.
• The new bounds improve upon previous mechanical experiments by over an order of magnitude.
• The results challenge a specific region of the CSL parameter space proposed by Adler.

Conclusions:

• The experiment successfully enhanced CSL noise detection using a novel test mass design.
• New experimental bounds were established for the CSL model at a characteristic length of 10⁻⁷ m.
• These findings provide significant constraints on theoretical models attempting to bridge quantum mechanics and classical reality.