Macroscopic features of quantum fluctuations in large N qubit system

TL;DR

This paper introduces a discrete Q-function for large N qubit systems, enabling visualization and approximate reconstruction of quantum states through collective measurements in the macroscopic limit.

Contribution

It presents a novel discrete Q-function tailored for symmetric measurements in large N qubit systems, facilitating analysis and state reconstruction.

Findings

Q-function effectively visualizes collective measurement results

Approximate state reconstruction is possible from low-order moments

Method enhances understanding of macroscopic quantum fluctuations

Abstract

We introduce a discrete Q-function of N qubit system projected into the space of symmetric measurements as a tool for analyzing general properties of quantum systems in the macroscopic limit. For known states the projected Q-function helps to visualize the results of collective measurements, and for unknown states it can be approximately reconstructed by measuring lowest moments of the of collective variables.