Quantumness Certification Via Non-demolition Measurements Establishes Criteria for Identifying Genuine Entanglement and Superposition
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Determining when a system truly exhibits quantum behaviour remains a fundamental challenge in physics, extending beyond simple calculations of complexity. Paolo Solinas from the University of Genova and INFN, alongside Stefano Gherardini from the National Institute of Optics CNR and the University of Florence, present a rigorous method for certifying this quantumness using Non-Demolition Measurements. Their work establishes a direct link between implementing these measurements and confirming the emergence of genuine quantum features, such as entanglement and superposition, in a way that parallels established tests of macrorealism. By detailing how these measurements reveal key indicators within a system’s quantum state, the researchers demonstrate a robust and practical approach applicable to both fundamental mechanics and the development of quantum technologies, offering a means to track quantum-to-classical transitions and certify genuinely quantum resources even in noisy environments. Determining whether observed correlations genuinely stem from quantum effects, or can be explained by classical means, presents a significant hurdle for researchers. This work addresses this issue by developing a practical and robust method for certifying quantumness based on non-demolition measurements, quantifying the degree to which a system violates classical bounds and providing a clear criterion for establishing the presence of quantum correlations. The researchers investigate the use of continuous variable measurements to detect quantumness in systems where direct state tomography is impractical. They demonstrate that by performing non-demolition measurements on a specific observable, it is possible to establish a lower bound on a quantifier of non-classicality, specifically the negativity, allowing for its reliable estimation without fully reconstructing the system’s quantum state. This approach proves resilient to experimental imperfections, such as detector noise and incomplete measurement efficiency. A key contribution is the development of a measurement strategy that optimises sensitivity to quantumness. By carefully selecting the observable and measurement parameters, the researchers maximise the ability to detect even weak quantum correlations, demonstrating its effectiveness through numerical simulations and theoretical analysis, and showing it outperforms existing protocols in various scenarios. The findings have important implications for quantum technologies, enabling verification of quantum behaviour in complex systems and paving the way for more robust and reliable quantum devices. Establishing whether a system is intrinsically quantum remains a challenge, but a rigorous criterion can be established by focusing on measurable features. This determination transcends classical simulability or computational complexity, requiring certification of the emergence and persistence of genuine quantum features, principally entanglement and superposition. Quantum Non-Demolition Measurements serve as the appropriate instrument for this certification, both theoretically and experimentally. Quantum Foundations, Decoherence and Measurement Problem This research comprehensively surveys the landscape of quantum physics, quantum information, and related fields, encompassing a wide range of topics from the fundamental principles of quantum mechanics to the latest advancements in quantum computation and thermodynamics. Core quantum physics is well represented, alongside a strong interest in the foundations of quantum mechanics, decoherence, and the measurement problem, exploring how quantum behaviour transitions to classical behaviour. A significant focus lies on quantum information theory, with references to key concepts like quantum entanglement, coherence, and resource theory, indicating a strong interest in the theoretical underpinnings of quantum information processing. The collection also explores quantum thermodynamics, investigating the thermodynamics of quantum systems and the role of coherence and entanglement in thermodynamic processes, and suggests an interest in understanding how decoherence affects quantum systems and the challenges of quantum measurement. The collection also highlights specific physical systems and experimental platforms, including superconducting circuits, cavity QED, and matter-wave interferometry, suggesting an interest in using these systems to study quantum phenomena and build quantum devices. Overall, the collection is interdisciplinary, balancing theoretical and experimental work, and reflecting current research trends in quantum physics and quantum information, with an emphasis on quantum resources like entanglement and coherence for potential technological applications.
Certifying Quantum Behaviour Via Non-Demolition Measurements This research establishes a rigorous method for determining whether a system genuinely exhibits quantum behaviour, moving beyond traditional approaches like Bell’s inequalities and Leggett-Garg inequalities.
The team demonstrates that by focusing on measurable features, specifically entanglement and superposition, and employing Non-Demolition Measurements (QNDM), it is possible to certify the presence of quantum characteristics, transcending simply identifying quantum correlations to confirm their actual emergence and persistence. The core achievement lies in linking QNDM implementation to a necessary and sufficient condition for violating macrorealism, a concept central to understanding the distinction between classical and quantum systems. Unlike previous methods which only offer sufficient conditions, this approach provides a definitive test for quantum behaviour, illustrated with concrete examples detailing how negative terms in quasi-probability distributions, resulting from QNDM, reveal genuine quantum features and can track the transition from quantum to classical behaviour when a system interacts with its environment. Acknowledging practical limitations, the authors highlight the difficulty of achieving perfectly non-invasive measurements, addressing this by exploring the robustness of QNDM protocols in the presence of noise and comparing their advantages to those of Leggett-Garg inequalities. Future research will likely focus on extending these techniques and applying them to a wider range of systems, particularly in the context of both fundamental mechanics and the development of quantum information technologies where controlled generation and certification of quantum resources are essential. 👉 More information 🗞 Quantumness certification via non-demolition measurements 🧠 ArXiv: https://arxiv.org/abs/2512.09734 Tags: