Stable macroscopic quantum superpositions

TL;DR

This paper introduces a new class of quantum states called concatenated GHZ states that are more stable against decoherence, enabling their use in quantum metrology with large systems and noisy environments.

Contribution

The authors propose a novel, inherently stable class of macroscopic entangled states, extending the utility of GHZ states for practical quantum technologies.

Findings

Concatenated GHZ states remain entangled at large scales.

These states are robust against noise and decoherence.

Potential for scalable experimental realization in ion traps.

Abstract

We study the stability of superpositions of macroscopically distinct quantum states under decoherence. We introduce a class of quantum states with entanglement features similar to Greenberger-Horne-Zeilinger (GHZ) states, but with an inherent stability against noise and decoherence. We show that in contrast to GHZ states, these so-called concatenated GHZ states remain multipartite entangled even for macroscopic numbers of particles and can be used for quantum metrology in noisy environments. We also propose a scalable experimental realization of these states using existing ion-trap set-ups.