An observable entanglement measure

Florian Mintert, Stephen Walburn, P. H. Souto Ribeiro +2 more

Shunlong Luo

F. Mintert

Chengjie Zhang, Sixia Yu, Qing Chen +2 more

We present observable lower bounds for several bipartite entanglement measures including entanglement of formation, geometric measure of entanglement, concurrence, convex-roof extended negativity, and $G$ concurrence. The lower bounds facilitate estimates of these entanglement measures for arbitrary finite-dimensional bipartite states. Moreover, these lower bounds can be calculated analytically from the expectation value of a single observable. Based on our results, we use several real experimental measurement data to get lower bounds of entanglement measures for these experimentally realized states. In addition, we also study the relations between entanglement measures.

Xi-Jun Ren, Zheng-Wei Zhou, Xingxiang Zhou +1 more

In this Brief Report, we prove that an analytically solvable two-qubit entanglement monotone introduced by Zhang et al. [Phys. Rev. A 76, 032306 (2007)] is no greater than the square of concurrence. This proof is based on the equivalence between Zhang et al.'s monotone and an observable entanglement measure for mixed states suggested by Mintert and Buchleitner [Phys. Rev. Lett. 98, 140505 (2007)]. Our result may clarify the connections between several recently defined entanglement measures and help understand their possible applications in quantum-information theory.

Aleksei Kodukhov, Dmitry Anatolevich Kronberg

We consider a situation, when a part of a pure entangled state is measured, which generates the ensemble of quantum states for the other part. We consider the connection between the uncertainty property of the observable and coherence of the dual ensemble for any entanglement measure.