arXiv subjects

R. Muthuganesan

Publications and source records attributed to R. Muthuganesan.

At least 19 recordsLinked to original sources

arXiv2026

Nonlocal effects via Local Quantum Fisher Information: Characterizations and Interpretations

We introduce a quantum Fisher information based measurement-induced nonlocality (QFI-MIN), which quantifies the maximal statistical distinguishability induced by locally invariant unitary dynamics. The proposed measure inherits desirable properties including positivity, local unitary invariance, monotonicity under local operations, and immunity to the local ancilla problem. Analytical expressions are obtained for pure states, arbitrary two-qubit states, and two-qubit X states, revealing a direct connection with entanglement for pure systems. We further establish clear operational interpretations of QFI-MIN in quantum parameter estimation, local channel discrimination, and correlation-assisted communication. Its behavior under amplitude damping, depolarizing, and generalized amplitude damping channels demonstrates robustness against environmental noise. The proposed framework provides a physically consistent and operationally meaningful quantifier of quantum correlations, linking nonlocality, quantum metrology, and quantum information processing

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arXiv2026

Quantum Correlation Hierarchy and Teleportation in Dephased Hydrogen Hyperfine System

We study the dynamics of quantum correlations in the hydrogen hyperfine spin system subject to Markovian phase noise. Treating the electron and proton spin degrees of freedom as an open two-qubit system governed by an isotropic hyperfine Hamiltonian and local dephasing, we obtain the exact time-dependent density matrix and derive analytical expressions for the full X-state family. We compute concurrence($C$), trace-distance measurement-induced nonlocality (Trace MIN--$\mathcal{N}_1$), and average steering coherence (ASC) in closed form and establish their strict ordering $ C(t)\leq \mathcal{N}_1(t)\leq \mathrm{ASC}(t) $ at all times. Entanglement is identified as the most fragile resource, undergoing sudden death at a finite time. Trace MIN exhibits dephasing-immune freezing for states with nonzero population imbalance, while ASC is the most robust quantity, persisting longest in every scenario studied.We additionally demonstrate that the dephased thermal hyperfine state serves as a resource for quantum teleportation, deriving a closed-form expression for the average fidelity and establishing that the teleportation advantage window coincides exactly with the entanglement survival interval, $\mathcal{F}_A > 2/3 \Longleftrightarrow \mathcal{C} > 0$, for the full X-state family with maximally mixed marginals. We identify four distinct dynamical regimes and map all three correlation measures onto directly measurable Pauli spin correlators, enabling experimental reconstruction of the full hierarchy without full state tomography.

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arXiv2026

Hybrid Qubit-Qutrit Quantum Battery: Nonclassicality and Energy Performance

We propose and analyze a hybrid qubit-qutrit quantum battery (QB) based on a mixed spin-1/2 and spin-1 system interacting via an anisotropic Heisenberg exchange coupling in the presence of a homogeneous magnetic field. The nonclassical properties of the system are characterized using the l1-norm of coherence and negativity, which quantify quantum coherence and entanglement, respectively. The performance of the quantum battery is evaluated through key indicators such as ergotropy, power, and capacity. Our results reveal that both ergotropy and power exhibit oscillatory dynamics, while the capacity remains constant over time. We further investigate the influence of system parameters and magnetic field strength on both quantum correlations and battery performance, demonstrating that nonclassicality plays a crucial role in enhancing energy-storage efficiency. Importantly, we establish a connection between the theoretical model and an experimentally realizable nickel-radical molecular complex, showing that quantum coherence, entanglement, and efficient energy storage persist even at room temperature. These findings provide a realistic pathway toward the implementation of hybrid qubit-qutrit quantum batteries in solid-state molecular platforms.

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arXiv2026

Hierarchy of quantum correlations in qubit-qutrit axially symmetric states

We investigate quantum correlations in a hybrid qubit-qutrit system subject to both axial and planar single-ion anisotropies, dipolar spin-spin interactions, and Dzyaloshinskii-Moriya (DM) coupling. Using Negativity, Measurement-Induced Non-locality (MIN), Uncertainty-Induced Nonlocality (UIN), and Bell nonlocality (as quantified by the CHSH inequality) as measures, we analyze the interplay between anisotropy parameters, magnetic fields, and temperature on the survival of quantum correlations. Our results demonstrate that Bell nonlocality and entanglement (Negativity) are highly sensitive to temperature and anisotropy, exhibiting sudden death under thermal noise, whereas MIN and UIN are significantly more robust. In particular, these discord-like and information-theoretic measures provide the largest baseline and persist even in parameter regions where entanglement vanishes, highlighting their suitability as a quantumness witness in realistic conditions. Notably, our Bell nonlocality study is tailored to the asymmetric qubit-qutrit setting by exploiting a recently developed qubit-qudit CHSH maximization framework. However, Bell nonlocality is confirmed to be the most fragile, surviving only in narrow parameter windows at low temperature. A key finding of this work is that we observe the fragility hierarchy: Bell nonlocality $\subseteq$ Negativity $\subseteq$ UIN(MIN) in the qubit-qutrit setting. These results provide deeper insight into the relative robustness of distinct quantum resources in anisotropic qubit-qutrit models, suggesting that quantum discord-like measures, such as MIN and UIN, may serve as more practical resources than entanglement for quantum information tasks in thermally active spin systems.

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arXiv2026

Quantum correlation and coherence in a mononuclear nickel-based molecular Magnet

We investigate the behaviors of thermal entanglement, quantum correlation beyond entanglement namely, measurement-induced nonlocality (MIN) and coherence in a nickel radical molecular magnet (Et3NH)[Ni(hfac)2L], whose spin-spin interactions are well described by the Heisenberg model. Using experimentally estimated coupling parameters, we compute the thermal state of the system and analyze the dependence of quantum resources on temperature and magnetic field. The results indicate that the quantum resources of the nickel-radical molecular magnet persist even at room temperature. We show that while negativity (the entanglement measure) rapidly vanishes with increasing temperature and magnetic field, measurement-induced nonlocality and quantum coherence remain comparatively more stable and persist in regions where entanglement is absent. These results highlight the significance of nonclassical correlations beyond entanglement in thermally activated spin systems and suggest that such molecular magnets could serve as viable platforms for quantum information processing in realistic conditions.

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arXiv2025

Tunable Dynamics of a Dipolar Quantum Battery: Role of Spin-Spin Interactions and Coherence

This study explores the energy storage dynamics of a quantum battery (QB) modeled using a dipolar spin system with Dzyaloshinskii-Moriya (DM) interaction. We examine the performance of this system in terms of ergotropy, instantaneous power, capacity, and quantum coherence using a two-qubit model. By solving the system's time evolution under cyclic unitary processes, we analyze how external parameters such as temperature, magnetic field, and DM interaction influence the charging behavior and quantum resources of the battery. The findings demonstrate that quantum coherence and DM interaction significantly enhance the energy storage efficiency and power output of the quantum battery, offering promising strategies for designing high-performance quantum energy storage devices. Furthermore, we investigate the performance of quantum battery under the influence of a common dephasing environment, which limits the long-term work-extraction capability of dipolar quantum batteries.

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arXiv2023

Weak measurement as a tool for studying coherence and quantum correlations in bipartite systems

In this article, we study quantum coherence of bipartite state from the perspective of weak measurement, which generalizes the notion of coherence relative to measurement. The is being illustrated by computing coherence for the well-known Bell diagonal and Wener states. We have also extended our investigation on quantum correlation measure and uncertainty relation in the weak measurement regime.

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arXiv2023

Thermal quantum correlations and Teleportation in a Graphene Sheet

The characterization of quantum resources in dynamical systems is one of the most important problems to be addressed in quantum information theory. In this article, we investigate the behaviors of quantum correlations and teleportation technique in a graphene sheet comprising of disordered electrons in a two-dimensional honeycomb lattice. We use three different measures of quantum correlations such as entanglement, measurement-induced nonlocality and uncertainty-induced nonlocality. We study the ground state properties of the graphene sheet from the perspective of quantum correlations. At thermal equilibrium, we show that the band parameter strengthens the quantum correlations whereas the scattering strength weakens the correlations. Finally, the impact of the system's parameters on the teleportation technique is also expounded.

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arXiv2023

Effects of intrinsic decoherence on discord-like correlation measures of two-qubit spin squeezing model

Quantum decoherence happens when the system interacts with the environment. Quantum correlation behaviours in the two-qubit spin squeezing model are studied under the influence of intrinsic decoherence. Quantitative results were determined, which depend on parameters of the physical system by checking different quantifiers of quantum correlation such as entanglement, local quantum uncertainty, trace distance discord and uncertainty-induced quantum nonlocality. We show that the entanglement suffers from intrinsic decoherence and exhibits sudden death, whereas the other measures are more robust against intrinsic decoherence. Further, we highlight the role of spin squeezing coupling constant and magnetic field.

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arXiv2023

Thermal quantum correlations and teleportation under PT-symmetric system

In this article, we exploit the different notions of quantumness measure to understand the properties of the Heisenberg XY model with and without PT-symmetric operation. In the absence of PT-symmetry, we study the significance of different measures, namely entanglement and measurement induced nonlocality (MIN), in the detection of the quantumness of the Heisenberg XY model. It is observed that the quantum correlations and teleportation fidelity monotonically decreases with respect to temperature. Furthermore, the intervention of PT-symmetric operation enhances the strengths of quantum correlation. In addition, we highlight the role of the system's parameters and PT-symmetric operation on the teleportation of a quantum state. Our results also emphasize that after the addition of PT-symmetric operation, the considered physical model remains a versatile resource to achieve successful teleportation of the quantum state.

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arXiv2022

Quantum correlations in a mixed spin-(1/2,1) Heisenberg dimer

In this article, we consider the heterodinuclear complex [Ni(dpt)(H2O)Cu(pba)].2H2O [pba =1,3-propylenebis(oxamato) and dpt = bis-(3-aminopropyl)amine] realized through the theoretical model of mixed spin-(1/2,1) coupled via Heisenberg interaction. We study the behaviors of thermal quantum correlations of the above material via Measurement-Induced Nonlocality (MIN) based on Hilbert-Schmidt norm and fidelity. We observe that the quantum correlation measures increase with the magnetic field in an unconventional way. The role of system parameters is also brought out at thermal equilibrium. The highlight of the results is that we are able to show the existence of room temperature quantum correlation using fidelity based MIN whereas the entanglement ceases to exist at 141K

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arXiv2022

Quantum Correlations and Coherence in a Moving Unruh-deWitt Detector

In this paper, we investigate the quantum correlations and coherence of two accelerating Unruh-deWitt detectors coupled to a scalar field in 3 + 1 Minkowski space-time. We show that the entanglement is completely destroyed in the limit of infinite acceleration while the local quantum uncertainty and l1-norm of coherence remain nonzero. In addition, we also highlight the role of Unruh temperature and energy spacing of detectors on quantum correlations for different choices of initial states.

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arXiv2022

Affinity-based geometric discord and quantum speed limits of its creation and decay

In this article, we define a faithful quantifiers of bipartite quantum correlation, namely geometric version of quantum discord using affinity based metric. It is shown that the newly-minted measure resolves the local ancilla problem of Hilbert-Schmidt measures. Exploiting the notion of affinity-based discord, we derive Margolus-Levitin (ML) and Mandelstamm-Tamm (MT) bounds for the quantum speed limit time for the creation and decay of quantum correlation. The dynamical study suggests that the affinity measure is a better resource compared to entanglement. Finally, we study the role of quantum correlation on quantum speed limit.

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arXiv2022

Characterizing nonbilocal correlation: A geometric perspective

Exploiting the notion of measurement-induced nonlocality [Phys.Rev. Lett. 106, 120401 (2011)], we introduce a new measure to quantify the nonbilocal correlation. We establish a simple relation between the nonlocal and nonbilocal measures for the arbitrary pure input states. Considering the mixed states as inputs, we derive two upper bounds of affinity-based nonbilocal measure. Finally, we have studied the nonbilocality of a different combinations of input states.

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arXiv2022

Characterizing nonclassical correlations of tensorizing states in a bilocal scenario

In the present paper, we attempt to address the question of "can tensorizing states have quantum advantages?". To answer this question, we exploit the notion of measurement-induced nonlocality (MIN) and advocate a fidelity based nonbilocal measure to capture the nonlocal effects of tensorizing states due to locally invariant von Neumann projective measurements. We show that the properties of the fidelity based nonbilocal measure are retrieved from that of MIN. Analytically, we evaluate the nonbilocal measure for any arbitrary pure state. The upper bounds of the nonbilocal measure based on fidelity are also obtained in terms of eigenvalues of correlation matrix. As an illustration, we have computed the nonbilocality for some popular input states.

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arXiv2021

Facets of nonlocal correlation under non-Hermitian system

In this article, we investigate the dynamics of a bipartite system under the action of a local non-Hermitian system. We study the quantum correlation of the bipartite system quantified by the entanglement, measurement-induced nonlocality (MIN) based on Hilbert-Schmidt norm, trace distance, and Bell inequality. We find that the quantum correlations of the system depend on the initial conditions and system parameters. We observe that the states with nonzero quantum correlation obey the Bell inequality even in the absence of entanglement. Moreover, the Bell inequality completely fails to manifest the nonlocality for the mixed quantum state. However, we have identified the nonlocal attributes of the mixed quantum state in terms of MIN and trace distance MIN. Our results show that the trace distance-based correlation is more robust against the nonunitary evolution compared to the other quantifiers.

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arXiv2021

Weak Measurement effects on dynamics of quantum correlations in a Two-atom System in Thermal Reservoirs

The dynamical behavior of quantum correlations captured by different forms Measurement-Induced Nonlocality (MIN) between two atoms coupled with thermal reservoirs is investigated and compared with the entanglement. It is shown that the MIN quantities are more robust, while noise causes sudden death in entanglement. Further, we quantified the quantum correlation with weak measurement, and the effect of measurement strength is observed. The role of mean photon number and weak measurement on quantum correlation is also highlighted.

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arXiv2021

Characterizing quantum ensemble using geometric measure of quantum coherence

The characterization of the quantum ensemble is a fundamental issue in quantum information theory and foundations. The ensemble is also useful for various quantum information processing. To characterize the quantum ensemble, in this article, we generalize the coherence measure of a state to the quantum ensemble. Exploiting the fidelity and affinity between the ensemble, we propose a quantumness quantifier for the quantum ensemble. It is shown that the proposed quantifier satisfies the necessary axioms of a bonafide measure of quantumness. Finally, we compute the quantumness of a few well-known ensembles.

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