Testing Spontaneous Collapse Models with Coulomb Mediated Squeezing

TL;DR

This paper proposes experimental methods using Coulomb interactions between nanospheres to set bounds on collapse models, achieving results comparable or superior to previous experiments and robust against certain noise extensions.

Contribution

It introduces Coulomb-mediated squeezing and entanglement tests as novel approaches to constrain collapse model parameters, with improved robustness and comparable sensitivity.

Findings

Bounds on CSL parameter comparable to X-ray experiments.

Robust bounds against coloured-noise extensions.

Entanglement-based tests can constrain collapse models.

Abstract

We show that detecting steady-state Coulomb-mediated reduction in the thermal variance of the differential motional mode of two nanospheres can bound the Continuous Spontaneous Localization (CSL) parameter ($\lambda_{{\text{CSL}}}$). For realistic experimental parameters, the resulting bounds are comparable to those obtained from X-ray emission experiments and surpass those set by bulk-heating ones. Unlike these latter experiments, our bounds are robust against plausible coloured-noise extensions of collapse models. In the short-time regime, we find that a weak Coulomb-induced entanglement-based test between two charged nanospheres initialized in ground state can provide constraints on $\lambda_{\text{CSL}}$ comparable to limits set by early X-ray experiments.