Robust Entanglement Dynamics in Driven Open Quantum Systems

TL;DR

This work investigates the dynamics of core quantum resources, specifically Negativity, Geometric Discord, and Quantum Memory-Assisted Entropic Uncertainty, in a driven open two-qubit system subject to amplitude damping, pure dephasing, and pulse-induced dephasing. By modeling the system with a Hamiltonian that includes XX and ZZ couplings and a hyperbolic secant drive, and evolving it under a Lindblad master equation, the authors assess how inter-qubit coupling, energy splitting, and drive parameters influence correlation generation, preservation, and memory effects. The study reveals a hierarchy of robustness where Negativity is the most fragile indicator, Quantum Discord persists longer, and QM-EUR captures residual quantum memory even when NG and QD are weak; driving pulses can either generate correlations from separable states or reinforce existing entanglement depending on the regime. These findings offer design principles for optimizing entanglement and coherence in noisy quantum devices, with implications for quantum computing, communication, and memory-enabled protocols.

Abstract

We investigate the dynamics of key quantum correlations - Negativity (NG), Quantum Discord (QD), and Quantum-Memory-Assisted Entropic Uncertainty (QM-EUR) - in a bipartite two-qubit system under the influence of external pulses and various decoherence channels, including amplitude damping (gamma_amp), pure dephasing (gamma_deph), and pulse-induced dephasing (G), while different regimes of inter-qubit coupling (Jzz, Jxx), qubit energy splitting (epsilon), and pulse parameters (A_pulse, beta_pulse) are explored. Our results show that inter-qubit coupling and energy splitting epsilon significantly influence the dynamics, producing pronounced oscillations in the weak-coupling regime and protecting pre-existing entanglement in the strong-coupling regime. NG is the most sensitive, QD persists longer revealing nonclassical correlations independent of entanglement, and QM-EUR reflects residual quantum memory and entropic uncertainty, showing that quantum signatures survive even when NG and QD are weak. Pulse amplitude and width effectively control the generation and dissipation of correlations, while the intensity of pulse-induced dephasing modulates the balance between sustained oscillations and rapid decoherence. The initial state also plays a crucial role: a partially entangled initial state is more resilient to perturbations, preserving correlations over time, whereas a separable state exhibits cycles of entanglement creation and destruction. Thus, by adjusting system parameters, it is possible to control the stability and lifetime of correlations and coherence, providing a framework to optimize quantum systems for applications requiring both strong entanglement and long-lasting coherence, such as quantum computing and secure communication.

Figures (8)

• Figure 1: Dynamics of quantum correlations under a driving pulse. The evolution of Negativity, Quantum Discord, and QM-Assisted Entropic Uncertainty is compared for a system starting in either a Bell state ($|\psi^{+}\rangle$) or a separable state ($|\psi^{00}\rangle$). The dynamics are strongly dependent on the qubit energy splitting, with the top row showing the weak-coupling regime ($\varepsilon = 0.01$) and the bottom row showing the strong-coupling regime ($\varepsilon = 5.0$). Simulation parameters: $J_{zz} = J_{xx} = 0.5$, $\gamma_{\text{amp}} = 0.01$, $\gamma_{\text{deph}} = 0.01$, $G = 0.01$. The driving pulse has an amplitude $A_{\text{pulse}} = 1.0$ and is centered at $t=15$.
• Figure 2: Dynamics of quantum correlations under a driving pulse. The evolution of Negativity (NG), Quantum Discord (QD), and QM-Assisted Entropic Uncertainty (QM-EUR) is compared for a system starting in either a Bell state ($|\psi^{+}\rangle$) or a separable state ($|\psi^{00}\rangle$). The dynamics are shown to be strongly dependent on the ZZ-coupling strength, with the top row corresponding to a weak interaction ($J_{zz} = 0.01$) and the bottom row to a strong interaction ($J_{zz} = 5.0$). Other simulation parameters are fixed: qubit energy splitting $\varepsilon=0.1$, XX-coupling $J_{xx}=1.0$, amplitude damping $\gamma_{\text{amp}}=0.01$, pure dephasing $\gamma_{\text{deph}}=0.01$, and $G=0.01$. The driving pulse has an amplitude $A_{\text{pulse}}=1.0$ and is centered at $t=15$.
• Figure 3: Dynamics of quantum correlations under a driving pulse. The evolution of Negativity (NG), Quantum Discord (QD), and QM-Assisted Entropic Uncertainty (QM-EUR) is compared for a system starting in either a Bell state ($|\psi^{+}\rangle$) or a separable state ($|\psi^{00}\rangle$). The dynamics are shown to be dependent on the XX-coupling strength, with the top row corresponding to a weak coupling ($J_{xx} = 0.1$) and the bottom row to a stronger coupling ($J_{xx} = 1.0$). Other simulation parameters are fixed: qubit energy splitting $\epsilon=0.1$, ZZ-coupling $J_{zz}=1.0$, amplitude damping $\gamma_{\text{amp}}=0.01$, pure dephasing $\gamma_{\text{deph}}=0.01$, and $G=0.01$. The driving pulse has an amplitude $A_{\text{pulse}}=1.0$ and is centered at $t=15$.
• Figure 4: Dynamics of quantum correlations under a driving pulse. The evolution of Negativity (NG), Quantum Discord (QD), and QM-Assisted Entropic Uncertainty (QM-EUR) is compared for a system starting in either a Bell state ($|\psi^{+}\rangle$) or a separable state ($|\psi^{00}\rangle$). The dynamics are shown for two different amplitude damping rates, with the top row corresponding to a weak damping ($\gamma_{\text{amp}} = 0.01$) and the bottom row to a stronger damping ($\gamma_{\text{amp}} = 0.1$). Other simulation parameters are fixed: qubit energy splitting $\varepsilon=0.1$, couplings $J_{zz}=J_{xx}=1.0$, pure dephasing $\gamma_{\text{deph}}=0.01$, and $G=0.01$. The driving pulse has an amplitude $A_{\text{pulse}}=1.0$ and is centered at $t=15$.
• Figure 5: Dynamics of quantum correlations under a driving pulse. The evolution of Negativity (NG), Quantum Discord (QD), and QM-Assisted Entropic Uncertainty (QM-EUR) is compared for a system starting in either a Bell state ($|\psi^{+}\rangle$) or a separable state ($|\psi^{00}\rangle$). The dynamics are shown for two different pure dephasing rates, with the top row corresponding to weak dephasing ($\gamma_{\text{deph}} = 0.01$) and the bottom row to stronger dephasing ($\gamma_{\text{deph}} = 0.1$). Other simulation parameters are fixed: qubit energy splitting $\varepsilon=0.1$, couplings $J_{zz}=J_{xx}=1.0$, amplitude damping $\gamma_{\text{amp}}=0.01$, and $G=0.01$. The driving pulse has an amplitude $A_{\text{pulse}}=1.0$ and is centered at $t=15$.