Optimize Parameters To Improve Quality Of Correlation In XYZ Spin Chain

Quantum information science is a new subject, which is based on the principle of quantum mechanics, for dealing with information and its main characteristic is the use of non-classical correlations. The earliest discovered non-classical correlation is quantum entanglement, quantum entanglement plays an important role in quantum information science. In 2001, another non-classical correlation, quantum discord, was also presented.With the further research, the phenomenon of quantum entanglement sudden death,i.e.,quantum entanglement is zero, has been discovered. When a sudden death occurs, there is still a quantum discord which is considered to be used in quantum information processing,but it is not a good time interval for quantum information processing. Due to the quantum gate operation requires a time interval, it needs to choose a time interval, that is longer than that of quantum gate operation, and strong and stable quantum correlation. Strong and stable quantum correlation is beneficial to the quantum information processing, and the correlation in the time interval can be regarded as high quality correlation.Take two quantum bit Heisenberg XYZ spin chain model as an example. The model is in an inhomogeneous magnetic field and influenced by Dzyaloshinskii-Moriya interaction.Use three measure methods which are concurrence, quantum discord and geometric measure of quantum discord, calculate the evolution of correlation with time. In order to compare the quality of quantum correlations, we have defined two quantities, the selective average correlation and the ripple coefficient to evaluate the quality of quantum correlation in a certain time interval. Use these two quantities, to evaluate the quality of the quantum correlation in different time intervals or of different parameters within the same time interval. We find that the correlations with the measures evolve similarly in the same time interval, and the qualities of correlations are all high or low. The values of quantum discord and geometric measure of quantum discord are low during the time interval of sudden death of entanglement, and then the qualities are low. Given the parameters of the system, we can find the time interval of quantum correlation with high quality; while optimizing the parameters of the system, we can find a higher quality of quantum correlation in a same time interval, and these may be beneficial for quantum information processing.