Quantum Measurement of Two-Qubit System in Damping Noise Environment

It is known that the inevitable interaction of the entangled qubits with their environments may result in the degradation of quantum correlation.We study the decoherence of two remote qubits under general local single- and two-sided amplitude-damping channel（ADC）.By using concurrence,quantum discord and Clauser-Horne-ShimonyHolt（CHSH） inequality,we find that the relation between the residual quantum correlations and the initial ones are different.Recently,Wang et al.[Int.J.Theor.Phys.54（2015） 5]showed that there exist a set of partially entangled states that are more robust than maximally entangled states in terms of the residual quantum correlation measured by concurrence,fully entangled fraction and quantum discord,respectively.Here we find that both in single- and two-sided ADC,only the evolution of CHSH inequality with the initial parameter is proportional to that of the initial nonlocality.That means the initial state with maximally nonlocality will retain its role in the evolution.It implies that the evolution of nonlocality may reveal the characteristics of quantum state better.Furthermore,we discuss the evolutions of the three different quantum measurements with the initial parameter under generalized amplitude damping channel（GADC） and find that they are all proportional to that of the initial state.