Quantifying Einstein-podolsky-rosen Steering And Expanding The Scope Of Steerability Of The Two Qubit State

This holistic property of compound quantum systems,which involves nonclassical correlations between subsystems,is a potential for many quantum processes,including "canonical" ones:quantum cryptography,quantum teleportation and dense coding.It appeared that this new resource is very complex and difficult to detect.EPR steering is a form of bipartite quantum correlation that is intermediate between entanglement and Bell nonlocality.It is detected via the violation of steering inequalities,which provide sufficient conditions for the steerability of quantum states.Furthermore,there is a sufficient criterion for guaranteeing that a two-qubit state is unsteerable.But there are some two qubit states that can not determine the steerability of the steering inequality and the sufficient criteria.Here we introduce a way of quantifying this phenomenon and use it to study the steerability of two qubit states.This article recommend a platonic solid measurement schemes.And then discuss the problem,namely expanding the scope of steerable,which guarantees that the state is steerable.In this paper,we use SDP to calculate the quantum steerability.The Matlab toolbox YALMIP which is used in the calculation of SDP is introduced.It is described how YALMIP can be used to model and solve optimization problems typically occurring in systems and control theory.