Smail Bougouffa

In this paper, we investigate the dynamics of quantum correlations in the ground-state hyperfine manifold of the hydrogen atom subjected to a static external magnetic field and local pure dephasing. The electron–proton spin pair is modeled as a bipartite two-qubit system evolving under the combined effects of hyperfine coupling, Zeeman splitting, and a Lindblad master equation that describes Markovian dissipative processes. Employing exact analytical solutions for the time-dependent density matrix elements (derived in the Markovian open-system framework), we quantify entanglement persistence via concurrence and state stability via Uhlmann fidelity with respect to the initial preparation. For an initial Werner state, numerical results reveal that the external magnetic field substantially modifies the system dynamics: Both concurrence and fidelity exhibit pronounced dependence on the Zeeman parameter, producing field-controlled oscillations, delayed entanglement sudden death, and altered decoherence rates. This behavior originates from Zeeman-induced lifting of hyperfine degeneracies, symmetry breaking of the isotropic Werner state, and redistribution of populations and coherences. Unlike previous studies that treat hyperfine interactions, Zeeman splitting, or decoherence in isolation, the present work provides a unified analytical treatment that simultaneously incorporates all three mechanisms. The findings underscore the competition between coherent hyperfine coupling and environmental noise and open new pathways for precision spectroscopy and robust quantum information protocols based on atomic spin degrees of freedom.

We investigate the time evolution of bipartite quantum correlations in the ground-state hyperfine manifold of the hydrogen atom subjected to an external magnetic field and independent Markovian dephasing. Treating the electron–proton spin pair as an effective two-qubit system, we derive the exact solution of the Lindblad master equation for an X-shaped initial state and quantify the dynamics using three complementary measures: entanglement of formation (through concurrence), quantum steering (through the CJWR inequality) and Bell nonlocality (through normalized CHSH violation). The dynamics are obtained within a unified open-system framework that combines hyperfine interaction, Zeeman splitting, and Markovian dissipation in a single analytically solvable Lindblad model, allowing a complete operator-level characterization of the correlation decay. This exact treatment provides a transparent link between the underlying spectral structure of the Hamiltonian and the observed hierarchy in the robustness of quantum correlations. Our results reveal that all three quantities exhibit damped oscillations whose frequency and decay rate are strongly tuned by the proton magnetic parameter through the Zeeman splitting. While entanglement decays relatively quickly, steering persists noticeably longer and Bell nonlocality proves to be the most fragile, confirming the expected hierarchy of quantum correlations under local dephasing. The external magnetic field emerges as a practical control knob that can extend the lifetime of these resources even in the presence of noise. These findings provide a clear physical picture of how hyperfine coupling, Zeeman effects, and environmental fluctuations jointly govern quantum coherence in atomic spin systems, with direct implications for spin-based quantum technologies and fundamental tests of nonlocality in realistic laboratory settings.

We examine non-classical correlations in separable systems through quantum dissonance and one-way quantum deficit. Our study focuses on the generation and dynamics of these correlations in hydrogen atoms influenced by dephasing and dissipative decoherence. We treat the electron–proton spin coupling in the hyperfine structure as a two-qubit quantum system, showing that quantum dissonance and a one-way deficit can emerge from initially classical configurations via this interaction. We further analyze the time evolution of the quantum dissonance and the one-way quantum deficit under dephasing and dissipative quantum dynamics. The results indicate that both measures exhibit a relatively slow decay under decoherence, highlighting their robustness against environmental effects. These insights highlight the promise of hydrogen atoms for robust quantum information protocols in noisy environments.

Quantum entanglement enables advanced quantum technologies, including secure communication and quantum computing. This study investigates the temporal dynamics of GHZ‐type entangled states in a three‐photon system subjected to pure environmental dephasing noise. We distinguish between Markovian regimes, characterized by memoryless decay, and non‐Markovian regimes, where environmental memory effects induce information backflow and can generate revivals of non‐separable quantum correlations. Employing genuine multipartite concurrence to quantify genuine tripartite entanglement and quantum mutual information to evaluate total correlations, we analyze the evolution of these quantum resources under symmetric and asymmetric photon‐environment couplings. Key tunable parameters – including the relative weighting of the two peaks in the double‐Gaussian environmental frequency profile, refractive index difference, spectral width, and overall frequency distribution – are explored within experimentally realistic ranges achievable with photonic platforms such as Fabry–Pérot cavities. Our results provide that non‐Markovian environments substantially enhance the robustness of entanglement, exhibiting prominent oscillatory revivals under symmetric peak weightings, whereas more asymmetric configurations result in faster monotonic decay. These findings propose practical strategies, such as optimized cavity configurations, to suppress decoherence and prolong the lifetime of multipartite quantum correlations, thereby supporting the development of more resilient photonic quantum states for quantum technologies.

We investigate the non-Markovian dynamics of quantum steering in a tripartite photonic system subject to dephasing noise. By developing a theoretical framework based on the single-photon dephasing model extended to three independent photons, we analyze the temporal evolution of steering measures S^A−BC and S^AB−C for two distinct classes of initial states: W-type entangled states and GHZ-type mixed entangled states. The system is studied under various environmental configurations, ranging from fully Markovian to fully non-Markovian regimes, with asymmetric distributions of memory effects across the three photons. Our results reveal that the dynamics of Gaussian steering are highly sensitive to both the number of photons coupled to non-Markovian environments and the specific partition of the system being considered. For W-states, non-Markovian effects induce oscillatory behavior with death-revival cycles, where the intervals of sudden death and revival amplitudes depend critically on the distribution of memory effects. For GHZ-states, we observe multiple death-revival cycles in some configurations and prolonged preservation of steering without complete sudden death in others. Notably, we find that non-Markovian environments can either enhance steering through information backflow or prove detrimental depending on which subsystems they are coupled to relative to the steering and steered parties. These findings demonstrate that non-Markovianity can serve as a resource for protecting specific types of quantum steering, but its effects are highly configuration-dependent, offering insights for quantum information processing tasks requiring the preservation of directional quantum correlations in photonic networks.

In the present work, we investigate the detection and control of quantum correlations in the hyperfine structure of hydrogen atoms under dissipative dynamics. The hydrogen atom serves as a fundamental platform for studying bipartite quantum correlations between the electron and proton spins, where entanglement is quantified by concurrence and EPR steering is witnessed through violation of the entropic steering inequality. By modeling the open-system evolution via the Lindblad master equation, we analyze the time-dependent behavior of concurrence, steering, and fidelity under varying dissipation rates. Numerical illustrations highlight the resilience of entanglement relative to steering in noisy environments, providing insights into the control of non-classical phenomena.