Studies On Quantum Steering And Quantum Steering Ellipsoid In Open Systems

Quantum correlation is an important phenomenon in quantum physics and has a wide range of applications in the field of quantum information technology.Quantum steering,as an important quantum correlation,also plays an important role in quantum information technology.Usually,since quantum channel is not uniform and has asymmetric property during actual information transmission,the study of the dynamic behavior of quantum steering in asymmetric noise channels is of great importance from both the theoretical and practical points of view.Moreover,in the decoherence condition,the most notable phenomenon is the sudden transition between quantum and classical decoherence.Since quantum steering ellipsoid can faithfully describe two-qubit quantum state,quantum steering ellipsoid can be used to visualize sudden transition of decoherence,which is valuable for studying the sudden transition of decoherence.In recent years,many physical and biological experiments have reported that the non-equilibrium property exhibited in the environment.Since the non-equilibrium property will affect the dynamic behavior of the quantum steering ellipsoid,it is of great significance to study the dynamical behavior of quantum steering ellipsoid in non-equilibrium environment.So,the research work in this paper is divided into three main aspects:Firstly,we study quantum steering dynamical behavior of two-qubit systems.For the one-sided asymmetric noise channel,the effect of several typical channels on the asymmetric decay of the steering is explored.The results show that asymmetric steering is directly related to the initial states as well as to the noise types.It is also demonstrated that asymmetric decay can characterize the properties of the channels to some extent.For the two-sided asymmetric noise channels,the results show that the behavior of the steering also depends on the initial states and the noise combination types.In addition,it is shown that for depolarizing and amplitude damping combined noise channels,the asymmetric steering is always present even if the initial state is highly symmetric.Secondly,we study that visualizing sudden transition of decoherence via quantum steering ellipsoid.The results show that the shape of the quantum steering ellipsoid under the phase flip noise channel and the generalized amplitude damping noise channel changes qualitatively at the sudden transition point in the decoherence process,and its geometry can change from a trivial ellipsoid to a prolate ellipsoid or an oblate ellipsoid.This finding sheds considerable light on the relationships between the sudden transition of decoherence and quantum steering ellipsoid with a geometrically visible view.In addition,the results based on one-norm geometric quantum discord are also discussed as a comparison briefly.Thirdly,we study the dynamical behavior of quantum steering ellipsoid in non-equilibrium environments.The results show that when a two-qubit system is coupled with a non-equilibrium environment,due to the sudden transition of quantum correlation and classical correlation under the effect of decoherence,the geometry of the quantum steering ellipsoid changes from a trivial ellipsoid to an oblate ellipsoid at the sudden transition point of decoherence.In addition,when the non-equilibrium parameter is larger,the time for the qualitative change in the geometry of the quantum steering ellipsoid is later,which indicates that the non-equilibrium property of the environment is an effective means to control the emergence of qualitative changes in the geometry of quantum steering ellipsoid.