Hierarchy in loss of nonlocal correlations of two-qubit states in noisy environments

Abstract

Composite quantum systems exhibit nonlocal correlations. These counterintuitive correlations form a resource for quantum information processing and quantum computation. In our previous work on two-qubit maximally entangled mixed states, we observed that entangled states, states that can be used for quantum teleportation, states that violate Bell-CHSH inequality, and states that do not admit local hidden variable description is the hierarchy in terms of the order of nonlocal correlations. In order to establish this hierarchy, in the present work, we investigate the effect of noise on two-qubit states that exhibit higher-order nonlocal correlations. We find that loss of nonlocal correlations in the presence of noise follows the same hierarchy, that is, higher-order nonlocal correlation disappears for small strength of noise, whereas lower-order nonlocal correlations survive strong noisy environment. We show this results for decoherence due to amplitude damping channel on various quantum states. However, we observe that same hierarchy is followed by states undergoing decoherence due to phase damping as well as depolarizing channels.