Symmetric inseparability and number entanglement in charge-conserving mixed states

Information-theoretic aspects of quantum inseparability of mixed states

Information-theoretic aspects of quantum inseparability of mixed states are investigated in terms of the α-entropy inequalities and teleportation fidelity. Inseparability of mixed states is defined and a complete characterization of the inseparable 2 × 2 systems with maximally disordered subsystems is presented within the Hilbert-Schmidt space formalism. A connection between teleportation and n...

Dichotomy of entanglement depth for symmetric states

Ji-Yao Chen, 2 Zhengfeng Ji, Nengkun Yu, 5, 3 and Bei Zeng 5, 6 State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing, China Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada Centre for Quantum Computation & Intelligent Systems, Faculty of Engineering and Information Technology, University of Technology, Sydney, NSW 200...

Entanglement of formation of rotationally symmetric states

Computing the entanglement of formation of a bipartite state is generally difficult, but special symmetries of a state can simplify the problem. For instance, this allows one to determine the entanglement of formation of Werner states and isotropic states. We consider a slightly more general class of states, rotationally symmetric states, also known as SU(2)-invariant states. These states are i...

Optimal entanglement criterion for mixed quantum states.

We develop a strong and computationally simple entanglement criterion. The criterion is based on an elementary positive map Phi which operates on state spaces with even dimension N > or = 4. It is shown that Phi detects many entangled states with a positive partial transposition (PPT) and that it leads to a class of optimal entanglement witnesses. This implies that there are no other witnesses ...

Bounding Polynomial Entanglement Measures for Mixed States