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An Operational Framework for Nonclassicality in Quantum Communication Networks

Quantum Science and Technology (arXiv overlay)

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Researchers developed a variational optimization framework to detect nonclassicality in quantum networks by violating classical communication bounds, demonstrating measurable advantages in information processing. The method uses classical processors to maximize quantum advantages in resource-constrained networks, scaling to large systems and noisy hardware via hybrid quantum-classical optimization techniques. Entanglement proves sufficient for nonclassicality in constrained networks, while multi-sender setups achieve advantages even without entanglement, relying solely on quantum communication channels. A single sender broadcasting to multiple receivers requires entanglement for any communication advantage, establishing a fundamental necessity for quantum correlations in such topologies. The framework enables real-world deployment, optimizing protocols and automating tasks in quantum networks, addressing practical challenges in noisy hardware implementation.

An Operational Framework for Nonclassicality in Quantum Communication Networks

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AbstractQuantum resources, such as entanglement or quantum communication, offer significant communication advantages in information processing. We develop an operational framework for realizing these communication advantages in resource-constrained quantum networks. The framework computes linear bounds on the input/output probabilities of classical networks with limited communication and globally shared randomness. Since the violation of these classical bounds witnesses nonclassicality, a measurable communication advantage, the framework maximizes the violation of the classical bound using variational quantum optimization methods tailored to the communication network and quantum resources. This operational framework for nonclassicality can be scaled on quantum computers or deployed in the field to optimize noisy quantum networks for communication advantages. Applying this framework, we investigate the nonclassicality of communication networks that are assisted by quantum resources. We find that entanglement between communication-constrained parties is sufficient for nonclassicality to be found, whereas in networks with multiple senders, quantum communication with no entanglement-assistance is sufficient for nonclassicality to be found. As a result, entanglement is necessary for nonclassicality when a single sender broadcasts to multiple receivers.Featured image: A classical processor optimizes quantum network hardware for a particular information processing task or demonstration of nonclassicality.Popular summaryQuantum communication resources, such as entanglement, can improve the information processing capabilities of communication networks. These communication advantages are directly related to a measurable property known as nonclassicality. In this work, we develop an approach for realizing nonclassicality by using a classical processor to optimize the communication advantage of simulated or real-world network. Our methods are compatible with quantum processors, making them scalable to large quantum networks and extensible to quantum networking hardware. We apply our operational framework for nonclassicality in a broad survey over all basic multiparty communication scenarios. In all cases, we find that entanglement is sufficient for communication advantage. When no entanglement is present, advantages can be realized if the network contains multiple senders who are equipped with point-to-point quantum communication. Furthermore, we prove that entanglement is necessary for communication advantage when a network contains a single sender who broadcasts to multiple receivers. In the future, our framework can be used optimize protocols or automate tasks in real-world quantum networks, helping to solve practical challenges with noisy quantum hardware.► BibTeX data@article{Doolittle2026operational, doi = {10.22331/q-2026-04-08-2052}, url = {https://doi.org/10.22331/q-2026-04-08-2052}, title = {An {O}perational {F}ramework for {N}onclassicality in {Q}uantum {C}ommunication {N}etworks}, author = {Doolittle, Brian and Leditzky, Felix and Chitambar, Eric}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {10}, pages = {2052}, month = apr, year = {2026} }► References [1] H. J. Kimble. The quantum internet. Nature, 453 (7198): 1023–1030, June 2008. 10.1038/nature07127. https://doi.org/10.1038/nature07127 [2] Rodney Van Meter. Quantum networking and internetworking. 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AbstractQuantum resources, such as entanglement or quantum communication, offer significant communication advantages in information processing. We develop an operational framework for realizing these communication advantages in resource-constrained quantum networks. The framework computes linear bounds on the input/output probabilities of classical networks with limited communication and globally shared randomness. Since the violation of these classical bounds witnesses nonclassicality, a measurable communication advantage, the framework maximizes the violation of the classical bound using variational quantum optimization methods tailored to the communication network and quantum resources. This operational framework for nonclassicality can be scaled on quantum computers or deployed in the field to optimize noisy quantum networks for communication advantages. Applying this framework, we investigate the nonclassicality of communication networks that are assisted by quantum resources. We find that entanglement between communication-constrained parties is sufficient for nonclassicality to be found, whereas in networks with multiple senders, quantum communication with no entanglement-assistance is sufficient for nonclassicality to be found. As a result, entanglement is necessary for nonclassicality when a single sender broadcasts to multiple receivers.Featured image: A classical processor optimizes quantum network hardware for a particular information processing task or demonstration of nonclassicality.Popular summaryQuantum communication resources, such as entanglement, can improve the information processing capabilities of communication networks. These communication advantages are directly related to a measurable property known as nonclassicality. In this work, we develop an approach for realizing nonclassicality by using a classical processor to optimize the communication advantage of simulated or real-world network. Our methods are compatible with quantum processors, making them scalable to large quantum networks and extensible to quantum networking hardware. We apply our operational framework for nonclassicality in a broad survey over all basic multiparty communication scenarios. In all cases, we find that entanglement is sufficient for communication advantage. When no entanglement is present, advantages can be realized if the network contains multiple senders who are equipped with point-to-point quantum communication. Furthermore, we prove that entanglement is necessary for communication advantage when a network contains a single sender who broadcasts to multiple receivers. In the future, our framework can be used optimize protocols or automate tasks in real-world quantum networks, helping to solve practical challenges with noisy quantum hardware.► BibTeX data@article{Doolittle2026operational, doi = {10.22331/q-2026-04-08-2052}, url = {https://doi.org/10.22331/q-2026-04-08-2052}, title = {An {O}perational {F}ramework for {N}onclassicality in {Q}uantum {C}ommunication {N}etworks}, author = {Doolittle, Brian and Leditzky, Felix and Chitambar, Eric}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {10}, pages = {2052}, month = apr, year = {2026} }► References [1] H. J. Kimble. The quantum internet. Nature, 453 (7198): 1023–1030, June 2008. 10.1038/nature07127. https://doi.org/10.1038/nature07127 [2] Rodney Van Meter. Quantum networking and internetworking. 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An Operational Framework for Nonclassicality in Quantum Communication Networks

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