Strict experimental test of macroscopic realism in a light-matter-interfaced system

TL;DR

This study implements a strict test of macroscopic realism using a light-matter system, creating large-scale entanglement to challenge classical views and demonstrate quantum superpositions at macroscopic levels.

Contribution

It introduces a new protocol to test macroscopic realism with solid-state components, creating large superposition states involving up to 76 atomic excitations.

Findings

Ruled out theories denying superpositions of large atomic ensembles.

Demonstrated entanglement between macroscopically distinguishable solid-state systems.

Extended the size of superposition states achievable in atomic systems.

Abstract

Macroscopic realism is a classical worldview that a macroscopic system is always determinately in one of the two or more macroscopically distinguishable states available to it, and so is never in a superposition of these states. The question of whether there is a fundamental limitation on the possibility to observe quantum phenomena at the macroscopic scale remains unclear. Here we implement a strict and simple protocol to test macroscopic realism in a light-matter interfaced system. We create a micro-macro entanglement with two macroscopically distinguishable solid-state components and rule out those theories which would deny coherent superpositions of up to 76 atomic excitations shared by 10^10 ions in two separated solids. These results provide a general method to enhance the size of superposition states of atoms by utilizing quantum memory techniques and to push the envelope of macroscopicity at higher levels.