Every quantum helps: Operational advantage of quantum resources beyond convexity

Kuroiwa, Kohdai; Takagi, Ryuji; Adesso, Gerardo; Yamasaki, Hayata

Abstract

Identifying what quantum-mechanical properties are useful to untap a superior performance in quantum technologies is a pivotal question. Quantum resource theories provide a unified framework to analyze and understand such properties, as successfully demonstrated for entanglement and coherence. While these are examples of convex resources, for which quantum advantages can always be identified, many physical resources are described by a nonconvex set of free states and their interpretation has so far remained elusive. Here we address the fundamental question of the usefulness of quantum resources without convexity assumption, by providing two operational interpretations of the generalized robustness measure in general resource theories. First, we characterize the generalized robustness in terms of a nonlinear resource witness and reveal that any state is more advantageous than a free one in some multicopy channel discrimination task. Next, we consider a scenario where a theory is characterized by multiple constraints and show that the generalized robustness coincides with the worst-case advantage in a single-copy channel discrimination setting. Based on these characterizations, we conclude that every quantum resource state shows a qualitative and quantitative advantage in discrimination problems in a general resource theory even without any specification on the structure of the free states.

Citation

Kuroiwa, K., Takagi, R., Adesso, G., & Yamasaki, H. (2024). Every quantum helps: Operational advantage of quantum resources beyond convexity. Physical Review Letters, 132(15), Article 150201. https://doi.org/10.1103/PhysRevLett.132.150201

• Journal Article Type: Article
• Acceptance Date: Feb 5, 2024
• Online Publication Date: Apr 8, 2024
• Publication Date: Apr 12, 2024
• Deposit Date: Feb 8, 2024
• Publicly Available Date: Apr 8, 2024
• Journal: Physical Review Letters
• Print ISSN: 0031-9007
• Electronic ISSN: 1079-7114
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 132
• Issue: 15
• Article Number: 150201
• DOI: https://doi.org/10.1103/PhysRevLett.132.150201
• Keywords: Quantum channels; Quantum measurements; Resource theories
• Public URL: https://nottingham-repository.worktribe.com/output/31154447
• Publisher URL: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.132.150201