Optimal entanglement witnesses based on local orthogonal observables

TL;DR

This paper improves the optimization of entanglement witnesses based on local orthogonal observables, providing methods to find optimal nonlinear witnesses and bounds on I-concurrence for bipartite systems.

Contribution

It introduces optimized nonlinear entanglement witnesses and establishes a lower bound on I-concurrence for higher-dimensional bipartite states.

Findings

Optimal nonlinear witnesses for pure bipartite states

Lower bounds on I-concurrence for higher-dimensional systems

Enhanced methods for entanglement detection

Abstract

We show that the entanglement witnesses based on local orthogonal observables which are introduced in [S. Yu and N.-L. Liu, Phys. Rev. Lett. 95, 150504 (2005)] and [O. G\"uhne, M. Mechler, G. T\'oth and P. Adam, Phys. Rev. A 74, 010301 (2006)] in linear and nonlinear forms can be optimized, respectively. As applications, we calculate the optimal nonlinear witnesses of pure bipartite states and show a lower bound on the I-concurrence of bipartite higher dimensional systems with our method.