# Experimental bilocality violation without shared reference frames

## TL;DR

This paper demonstrates an experimental scheme to violate bilocality without shared reference frames, addressing practical constraints and enabling more robust quantum network tests.

## Contribution

It introduces and experimentally validates a new method for bilocality violation that does not depend on shared reference frames, improving robustness in quantum network experiments.

## Key findings

- False positive nonbilocal correlations can occur with independent sources.
- The proposed scheme successfully violates bilocality without shared reference frames.
- This approach enhances the feasibility of quantum network tests.

## Abstract

Non-classical correlations arising in complex quantum networks are attracting growing interest, both from a fundamental perspective and for potential applications in information processing. In particular, in an entanglement swapping scenario a new kind of correlations arise, the so-called nonbilocal correlations that are incompatible with local realism augmented with the assumption that the sources of states used in the experiment are independent. In practice, however, bilocality tests impose strict constraints on the experimental setup and in particular to presence of shared reference frames between the parties. Here, we experimentally address this point showing that false positive nonbilocal quantum correlations can be observed even though the sources of states are independent. To overcome this problem, we propose and demonstrate a new scheme for the violation of bilocality that does not require shared reference frames and thus constitute an important building block for future investigations of quantum correlations in complex networks.