Probing Spontaneous Wave-Function Collapse with Entangled Levitating Nanospheres

TL;DR

This paper proposes an experimental protocol using entangled levitating nanospheres to test wave function collapse models, which modify quantum mechanics at macroscopic scales, by observing changes in entanglement.

Contribution

It introduces a novel protocol to detect wave function collapse effects through entanglement measurements of nanospheres in a cavity.

Findings

Collapse noise reduces steady-state entanglement significantly.

Entanglement scaling differs with and without collapse effects.

Protocol can unambiguously identify collapse model signatures.

Abstract

Wave function collapse models are considered as the modified theories of standard quantum mechanics at the macroscopic level. By introducing nonlinear stochastic terms in the Schr\"odinger equation, these models make predictions, differently from those of standard quantum mechanics, that it is fundamentally impossible to prepare macroscopic systems in macroscopic superpositions. The validity of these models can only be examined by experiments and hence efficient protocols for this kind of experiments are highly needed. Here we provide a protocol that is able to probe the postulated collapse effect by means of the entanglement of the center-of-mass motion of two nanospheres optically trapped in a Fabry-P\'erot cavity. We show that the collapse noise results in large reduction of the steady-state entanglement and the entanglement, with and without the collapse effect, shows distinguishable scalings with certain system parameters, which can be used to unambiguously determine the effect of these models.