Two-qubit mixed states and teleportation fidelity: Purity, concurrence, and beyond
Abstract
To explore the properties of a two-qubit mixed state, we consider quantum teleportation. The fidelity of a teleported state depends on the resource state purity and entanglement, as characterized by concurrence. Concurrence and purity are functions of state parameters. However, it turns out that a state with larger purity and concurrence, may have comparatively smaller fidelity. By computing teleportation fidelity, concurrence and purity for two-qubit X-states, we show it explicitly. We further show that fidelity changes monotonically with respect to functions of parameters - other than concurrence and purity. A state with smaller concurrence and purity, but larger value of one of these functions has larger fidelity. These functions, thus characterize nonlocal classical and/or quantum properties of the state that are not captured by purity and concurrence alone. In particular, concurrence is not enough to characterize the entanglement properties of a two-qubit mixed state.
Keywords
Cite
@article{arxiv.1810.11995,
title = {Two-qubit mixed states and teleportation fidelity: Purity, concurrence, and beyond},
author = {Sumit Nandi and Chandan Datta and Arpan Das and Pankaj Agrawal},
journal= {arXiv preprint arXiv:1810.11995},
year = {2018}
}