The Dynamics of Quantum-Memory-Assisted Entropic Uncertainty of Two-Qubit System in the XY Spin Chain Environments with Dzyaloshinsky-Moriya Interaction

Abstract

We investigate the dynamical behaviors of quantum-memory-assisted (QMA) entropic uncertainty for the central two-qubit system coupled to the N-site spin XY chain environment with z-component Dzyaloshinsky-Moriya (DM) interaction and external magnetic field, asymmetrically. The results show that the dynamics of QMA entropic uncertainty for a pair of Pauli observables are oscillatory and ascending gradually with evolution time, which is anti-correlated to the entanglement of the two-qubit system. We also find that QMA entropic uncertainty exhibits sudden change phenomena near the critical point of quantum phase transform both in the case of weak and strong coupling regimes, which can act as a new witness of the critical point of quantum phase transition. Meanwhile, the DM interactions of the spin chain environment have non-equivalent effects on the QMA entropic uncertainty when the external magnetic field strength is far from the critical point. Furthermore, the asymmetricallity of the qubit-environment couplings has slightly effects on QMA entropic uncertainty in the case of strong coupling regime of the two-qubit system. While, in the weak coupling regime of the two-qubit system, QMA entropic uncertainty is very sensitive to the asymmetricallity of qubit-environment couplings. Finally, the larger the number of spin sites of the environment, the more quickly the QMA entropic uncertainty increases to the maximal value both in the weak and strong coupling regimes of the two-qubit system.