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European Journal of Pure and Applied Mathematics

Quantum Information Resources for two Superconducting Artificial Atoms

Nour Zidan, Salman Alsaeed, Abdel-Baset Mohamed

Published Feb 21, 2026• 0 citations
Publisher

Abstract

This study investigates the emergency effects of coupling two superconducting-charge-qubits on thermal equilibrium nonlocality behaviors, including Bell inequality violation (BIV) nonlocality and uncertainty-induced (UI) quantum nonlocality beyond logarithmic negativity entanglement (LN entanglement). Thermal entangled two superconducting-charge-qubits states can exhibit UI-quantum nonlocality without BIV nonlocality, highlighting the hierarchical relationship between these resources. Increasing Josephson-qubit energies enhances resistance to degradation at high temperatures. Large differences in Josephson-qubit energies amplify the degradation temperature for nonlocalities. Coupling of the two qubits improves robustness, preservation, and thermal interval of maximal and partial nonlocalities. The temperatures for sudden death of entanglement depend on Josephson qubit energies, their difference, and mutual coupling. Finally, we explore the symmetrical dependence of thermal two superconducting-qubit nonlocality on Josephson-qubit energies and mutual qubit coupling.

DOI
10.29020/nybg.ejpam.v19i1.7087

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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.
Abstract Quantum correlations in two superconducting (SC) qubits, placed in an SC-cavity and driven by noise fields, are investigated by using quantum discord (QD) and measurement-induced nonlocality with quantum entanglement (QE). It was found that the initial values of QD and measurement-induced non-locality (MIN) grow from zero-values to non-zero values. This growth of quantum correlations is due to the unitary qubits–field interaction. It is found that by increasing the coupling to the thermal environment, the generated correlations (of QD, MIN and QE) return to their zero-values and the phenomena of the sudden death and sudden birth only occur for QE. It is interesting to note that the state of two superconducting qubits has the quantum discord and quantum nonlocality without entanglement. The ability of the thermal field parameter for the disappearance of the generated correlations depend on the spontaneous emission parameter and vice versa.