Quantum violation of local causality in urban network with hybrid photonic technologies

Abstract

Quantum networks play a crucial role for distributed quantum information processing, enabling the establishment of entanglement and quantum communication among distant nodes. Fundamentally, networks with independent sources allow for new forms of nonlocality, beyond the paradigmatic Bell's theorem. Here we implement the simplest of such networks -- the bilocality scenario -- in an urban network connecting different buildings with a fully scalable and hybrid approach. Two independent sources using different technologies, respectively a quantum dot and a nonlinear crystal, are used to share photonic entangled state among three nodes connected through a 270 m free-space channel and fiber links. By violating a suitable non-linear Bell inequality, we demonstrate the nonlocal behaviour of the correlations among the nodes of the network. Our results pave the way towards the realization of more complex networks and the implementation of quantum communication protocols in an urban environment, leveraging on the capabilities of hybrid photonic technologies.

References in corpus (22)

• The Quantum Internet
• Secure Quantum Key Distribution
• Ground-to-satellite quantum teleportation
• Measurement device independent quantum key distribution over 404 km optical fibre
• Quantum teleportation using active feed-forward between two Canary Islands
• Quantum teleportation and entanglement distribution over 100-kilometre free-space channels
• Progress in satellite quantum key distribution
• Sending-or-Not-Sending with Independent Lasers: Secure Twin-Field Quantum Key Distribution Over 509 km
• Quantum theory based on real numbers can be experimentally falsified
• Bell nonlocality in networks
• Information-Theoretic Implications of Quantum Causal Structures
• Quantum cryptography with highly entangled photons from semiconductor quantum dots
• Theory-independent limits on correlations from generalised Bayesian networks
• Nonlocal correlations in the star-network configuration
• A unifying framework for relaxations of the causal assumptions in Bell's theorem
• Ruling out real-valued standard formalism of quantum theory
• Bilocal Bell inequalities violated by the quantum Elegant Joint Measurement
• GaAs quantum dots grown by droplet etching epitaxy as quantum light sources
• Four-dimensional entanglement distribution over 100 km
• Experimental bilocality violation without shared reference frames
• Demonstrating the power of quantum computers, certification of highly entangled measurements and scalable quantum nonlocality
• Experimental robust self-testing of the state generated by a quantum network

Cited by in corpus (6)

• Experimental nonclassicality in a causal network without assuming freedom of choice
• Regarding the Maximal Qubit Violations of n-Locality in Star and Chain Networks
• Inferring Quantum Network Topology using Local Measurements
• Signatures of the Optical Stark Effect on Entangled Photon Pairs from Resonantly-Pumped Quantum Dots
• Optimal quantum key distribution networks: capacitance versus security
• Classification of joint quantum measurements based on entanglement cost of localization