Device-Independent Full Network Nonlocality for Arbitrary-Party and Unbounded-Input Scenario

Area of Science:

• Quantum Information Theory
• Quantum Foundations
• Multiparty Quantum Systems

Background:

• Multiparty Bell nonlocality differs from standard single-source Bell nonlocality.
• Full network nonlocality (FNN) characterizes quantum correlations unachievable by local-nonlocal models.
• Previous FNN demonstrations were limited to specific network structures and measurement settings.

Purpose of the Study:

• To demonstrate FNN in more general network scenarios.
• To introduce novel network inequalities for detecting FNN.
• To propose experimentally feasible methods for certifying distributed quantum nonlocality.

Main Methods:

• Demonstration that many existing network inequalities do not exhibit FNN.
• Introduction of arbitrary-party and unbounded-input network inequalities for star-shaped and linear-chain networks.
• Analytic derivation of optimal quantum violations for these inequalities.

Main Results:

• Identified a class of network inequalities that do not exhibit FNN.
• Developed new inequalities whose optimal quantum violation demonstrates FNN.
• Showcased that FNN can be certified with simpler experimental setups (two-output measurements).

Conclusions:

• The developed inequalities provide a robust method for detecting genuine distributed nonlocality in quantum networks.
• The findings advance the understanding of multiparty quantum correlations and their experimental verification.
• The approach facilitates device-independent self-testing of quantum devices.