# Coherence, Asymmetry, and Quantum Macroscopicity

## TL;DR

This paper introduces a new measure of quantum coherence and macroscopicity that accounts for asymmetry and microscopic superpositions, providing a framework to analyze quantum macroscopicity in spin systems.

## Contribution

It proposes a novel coherence measure extended to quantify quantum macroscopicity, incorporating a cutoff to distinguish microscopic from macroscopic superpositions.

## Key findings

- New measure of quantum coherence and macroscopicity introduced
- Application to N-partite spin systems demonstrates effectiveness
- Method to exclude microscopic superpositions via cutoff

## Abstract

We investigate a measure of quantum coherence and its extension to quantify quantum macroscopicity. The coherence measure can also quantify the asymmetry of a quantum state with respect to a given group transformation. We then show that a weighted sum of asymmetry in each mode can be applied as a measure of macroscopic coherence. To exclude the effects of microscopic superpositions, we suggest a method to introduce a cutoff to the weighted sum that will specify the macroscopic portion of the coherence. This cutoff may be interpreted as the fuzziness for a given measurement outcome. Based on the suggested measures, we investigate the quantum macroscopicity for particular concrete examples in N-partite spin systems.