Abstract Quantum correlations extend beyond entanglement and play a central role in quantum information. Quantum discord captures nonclassical correlations that can persist in separable states. We present the first systematic geometric and operational analysis of MICT-discord in two-qubit systems, integrating numerical validation, scaling laws, noise robustness, and resource geometry. We validate MICT-discord against analytic benchmarks, uncover distinct scaling for entangled versus separable classes, and identify a crossover regime where separable states exceed entangled ones in discord, challenging monotonic assumptions. Under depolarizing and amplitude-damping channels, MICT-discord shows channel-dependent resilience, highlighting potential utility for NISQ devices. In contrast, maximally entangled mixed states (MEMS) expose limitations where MICT-discord fails to detect correlations at low purity. Geometric resource analysis delineates the convex hull boundaries of separable states and reveals the clustering of entangled states in high-discordance regions, providing operational thresholds. Overall, MICT-discord emerges as a structured, coherence-sensitive measure with demonstrated strengths in scaling and noise scenarios, alongside clear limitations in mixed-state regimes. Our results establish a reproducible, geometry-informed framework for discord analysis and suggest practical pathways for resource classification and benchmarking in quantum.
Abstract Quantum correlations extend beyond entanglement and play a central role in quantum information. Quantum discord captures nonclassical correlations that can persist in separable states. We present the first systematic geometric and operational analysis of MICT-discord in two-qubit systems, integrating numerical validation, scaling laws, noise robustness, and resource geometry. We validate MICT-discord against analytic benchmarks, uncover distinct scaling for entangled versus separable classes, and identify a crossover regime where separable states exceed entangled ones in discord, challenging monotonic assumptions. Under depolarizing and amplitude-damping channels, MICT-discord shows channel-dependent resilience, highlighting potential utility for NISQ devices. In contrast, maximally entangled mixed states (MEMS) expose limitations where MICT-discord fails to detect correlations at low purity. Geometric resource analysis delineates the convex hull boundaries of separable states and reveals the clustering of entangled states in high-discordance regions, providing operational thresholds. Overall, MICT-discord emerges as a structured, coherence-sensitive measure with demonstrated strengths in scaling and noise scenarios, alongside clear limitations in mixed-state regimes. Our results establish a reproducible, geometry-informed framework for discord analysis and suggest practical pathways for resource classification and benchmarking in quantum.
Abstract Quantum correlations extend beyond entanglement and play a central role in quantum information. Quantum discord captures nonclassical correlations that can persist in separable states. We present the first systematic geometric and operational analysis of MICT-discord in two-qubit systems, integrating numerical validation, scaling laws, noise robustness, and resource geometry. We validate MICT-discord against analytic benchmarks, uncover distinct scaling for entangled versus separable classes, and identify a crossover regime where separable states exceed entangled ones in discord, challenging monotonic assumptions. Under depolarizing and amplitude-damping channels, MICT-discord shows channel-dependent resilience, highlighting potential utility for NISQ devices. In contrast, maximally entangled mixed states (MEMS) expose limitations where MICT-discord fails to detect correlations at low purity. Geometric resource analysis delineates the convex hull boundaries of separable states and reveals the clustering of entangled states in high-discordance regions, providing operational thresholds. Overall, MICT-discord emerges as a structured, coherence-sensitive measure with demonstrated strengths in scaling and noise scenarios, alongside clear limitations in mixed-state regimes. Our results establish a reproducible, geometry-informed framework for discord analysis and suggest practical pathways for resource classification and benchmarking in quantum.
Abstract Quantum discord captures nonclassical correlations beyond entanglement and plays a piv-otal role in quantum communication, computation, and thermodynamics. Traditionally defined via entropy-based asymmetries in mutual information, discord remains conceptually rich but operationally opaque particularly in noisy or mixed-state regimes where entanglement vanishes yet quantum advantage persists. In this work, we introduce a novel formulation of discord based on Measurement-Induced Coherence Transfer (MICT). Rather than quantifying information imbalance, MICT discord measures the coherence gained in subsystem A when a projective measurement is performed on subsystem B. This directional, coherence-centric perspective reframes discord as a physically observable transfer process, firmly grounded in the resource theory of quantum coherence. Numerical simulations on Werner states validate the framework and reveal strong basis sensitivity: computational-basis measurements yield vanishing discord, whereas Hadamard-basis measurements consistently produce maximal coherence. This sharp divergence from standard discord measures underscores the operational significance of measurement choice in coherence-aware protocols. Finally, we discuss experimental feasibility, showing that MICT discord can be estimated via standard quantum state tomography and coherence monotones. Our results position MICT discord as a practical diagnostic and a new lens for interpreting quantum correlations, with potential applications in coherence-based benchmarking, quantum thermodynamics, and noise-resilient communication protocols.
Abstract Quantum discord has emerged as a robust diagnostic of nonclassical correlations beyond entanglement, particularly relevant for noisy intermediate-scale quantum (NISQ) devices. We present an experimental study of measurement-induced coherence-transfer (MICT) discord proxies implemented on IBM Quantum hardware and benchmarked against simulator results. Discord and coherence landscapes, collapse maps, fidelity maps, and histograms demonstrate that collapse domains remain identifiable despite gate errors and readout noise. Fidelity difference maps quantify deviations between hardware and simulator, while summary metrics establish reproducible benchmarks for discord/coherence suppression and resilience. These findings indicate that discord-related signatures persist as global, topology-informed features in the presence of realistic noise, positioning discord and measurement-induced coherence as practical diagnostics for NISQ benchmarking and quantum machine-learning pipelines.
Abstract Quantum discord has emerged as a resource that extends beyond entanglement, yet its operational role remains underexplored. In this work, we introduce the Measurement-Induced Coherence Transfer (MICT) framework as both a theoretical and experimental diagnostic for coherence transfer. The MICT-Discord analysis establishes thresholds, scaling behavior, and noise resilience, mapping the geometry of discord across entanglement and measurement parameters. Complementing this, the MICT-Benchmark validates these predictions on IBM Quantum hardware through teleportation, superdense coding, and QKD protocols. The comparative results between the simulator, the ideal state vector,and the hardware output reveal discord as a sensitive witness of backend stability and coherence degradation. Together, MICT-Discord and MICT-Benchmark provide a reproducible suite for evaluating quantum platforms, positioning Discord as a practical diagnostic tool. Future directions include multipartite discord (GHZ/W states), error correction primitives, dynamic circuits with feed-forward, and cross-architecture reproducibility.
Abstract Quantum discord has emerged as a measure of nonclassical correlations beyond entanglement, yet its operational relevance under realistic noise remains uncertain. We present a dual validation framework that combines extensive simulation sweeps with experimental runs on the 156-qubit \texttt{ibm\_fez} backend. By overlaying depolarizing and amplitude-damping noise models with hardware accuracy curves, we show that discord-based features remain predictive in the presence of substantial device noise. Hardware accuracy points are reported with 95\% binomial confidence intervals to ensure statistical rigor and reproducibility. The close alignment between hardware results and depolarizing simulations confirms that the theoretical framework captures operational realities of near-term quantum processors. These findings establish discord as a robust diagnostic resource for noisy intermediate-scale quantum (NISQ) devices, bridging theory and experiment. Discord features remain predictive under both simulated and real quantum noise, positioning them as a cornerstone for hardware-aware quantum machine learning.
We investigate the quantum correlations in an axially symmetric hybrid qubit-qutrit system subjected to different noisy environments. We first introduce a physical model and analyze its Hamiltonian structure, emphasizing the role of hybrid dimensionality and axial symmetry. The effects of decoherence are then examined under two local noise mechanisms, namely dephasing and phase-flip channels, acting on the qubit and qutrit subsystems in both symmetric and asymmetric configurations. Quantum correlations are quantified using negativity to capture entanglement and quantum discord based on linear entropy to characterize more general nonclassical correlations. Our results show that both thermal fluctuations and phase noise lead to a monotonic degradation of quantum correlations, with increasing temperature accelerating coherence loss and inducing entanglement sudden death at finite temperatures. While negativity vanishes abruptly under sufficiently strong noise, quantum discord persists beyond the entanglement threshold, revealing residual quantum correlations in mixed states. We further demonstrate that asymmetric noise configurations significantly enhance the robustness of both entanglement and discord by partially shielding coherence in the less affected subsystem. A comparative analysis reveals that phase-flip noise is more destructive than pure dephasing, leading to faster suppression of quantum correlations.