Experimental demonstration of nonbilocal quantum correlations.

Area of Science:

• Quantum Information Science
• Quantum Foundations
• Quantum Networking

Background:

• Quantum mechanics allows for correlations violating local realistic models, typically studied in bipartite systems using Bell inequalities.
• Standard local hidden variable models explain quantum correlations but fail to capture certain complex quantum phenomena.
• Quantum networks require understanding correlations in multipartite systems with independent entanglement sources.

Purpose of the Study:

• To investigate correlations in three-party systems connected by two independent entangled states.
• To explore the novel concept of bilocal models involving two independent hidden variables.
• To experimentally demonstrate nonbilocal correlations in a quantum network and assess their noise resilience.

Main Methods:

• Construction of a linear three-node quantum network using photonic qubits.
• Generation and manipulation of two independent entangled states between three parties.
• Violation of a Bell-like inequality specifically designed for bilocal models.

Main Results:

• Experimental demonstration of nonbilocal correlations, confirming predictions beyond bilocal models.
• Observation that nonbilocality in this three-party network is more robust to noise than standard Bell nonlocality.
• Validation of bilocal models as a framework for describing quantum networks with independent sources.

Conclusions:

• The study experimentally confirms the existence of nonbilocal correlations in a realistic quantum network.
• Nonbilocality offers a potential advantage in quantum communication protocols due to its enhanced noise tolerance.
• This work provides a foundation for exploring more complex quantum network structures and their unique quantum properties.