# Quantum Correlations in Nonlocal BosonSampling

## TL;DR

This paper demonstrates a distributed quantum computation protocol where output correlations exhibit true quantum nonclassicality, enabling quantum advantages in information processing despite classically simulable local measurement outcomes.

## Contribution

It introduces a protocol showing that global phase-space nonclassicality in output states signifies genuine quantum correlations, even when local outcomes are classically simulable.

## Key findings

- Output measurement correlations cannot be efficiently simulated classically.
- Local measurement outcomes are classically simulable.
- Global phase-space nonclassicality indicates true quantum correlations.

## Abstract

Determination of the quantum nature of correlations between two spatially separated systems plays a crucial role in quantum information science. Of particular interest is the questions of if and how these correlations enable quantum information protocols to be more powerful. Here, we report on a distributed quantum computation protocol in which the input and output quantum states are considered to be classically correlated in quantum informatics. Nevertheless, we show that the correlations between the outcomes of the measurements on the output state cannot be efficiently simulated using classical algorithms. Crucially, at the same time, local measurement outcomes can be efficiently simulated on classical computers. We show that the only known classicality criterion violated by the input and output states in our protocol is the one used in quantum optics, namely, phase-space nonclassicality. As a result, we argue that the global phase-space nonclassicality inherent within the output state of our protocol represents true quantum correlations.