# Macroscopic quantum states: measures, fragility and implementations

## TL;DR

This review critically examines measures of macroscopic quantumness, discusses challenges in creating and detecting such states, and surveys recent experimental advances and their implications for foundational and practical quantum applications.

## Contribution

It provides a comprehensive analysis of measures, challenges, and recent experimental progress in the field of macroscopic quantum states.

## Key findings

- Analysis of various measures of macroscopic quantumness
- Discussion of difficulties in creating and maintaining macroscopic quantum states
- Survey of recent experimental advances in observing macroscopic quantum phenomena

## Abstract

Large-scale quantum effects have always played an important role in the foundations of quantum theory. With recent experimental progress and the aspiration for quantum enhanced applications, the interest in macroscopic quantum effects has been reinforced. In this review, we critically analyze and discuss measures aiming to quantify various aspects of macroscopic quantumness. We survey recent results on the difficulties and prospects to create, maintain and detect macroscopic quantum states. The role of macroscopic quantum states in foundational questions as well as practical applications is outlined. Finally, we present past and on-going experimental advances aiming to generate and observe macroscopic quantum states.