The Comparative Study Of Quantum Entanglement And Quantum Discord For Coupled Superconducting Qubit

In this paper, we mainly focus on the quantum correlation dynamic evolution ofcoupled qubits in non-Markovian process and in the squeezed vacuum reservoir. Weseparately use the concurrence and quantum discord to measure the quantumcorrelation. The main work as follows:(1) Considering the strength coupling between the superconducting qubits andthe environment and its dynamic evolution is a non-Markovian process, therefore,using the non-Markovian quantum master equation, we investigate the dynamicevolution of the system quantum correlation when the coupled superconducting qubitsbegin with the initial bipartite X-type quantum system. We separately investigate howthe initial quantum parameters and the environment temperature affect theconcurrence and quantum discord. The results show that in the given superconductingcircuit environment, the quantum discord is more robust than concurrence with thesame external condition, and the decoherence ability of the quantum discord is morestrong than the concurrence.(2) Because the squeezed optic field is important to the quantum information,we investigate and compare the quantum discord and concurrence of coupled qubits insqueezed vacuum reservoir. We find that the quantum discord and entanglementperform completely oppositely with the change of squeezed parameters. The quantumdiscord survives longer with the increase of squeezed amplitude parameter and on thecontrary, the entanglement dead faster. In the high squeezed amplitude parameter, thequantum discord can keep nonzero, which indicates that the quantum discord is morerobust than entanglement in squeezed vacuum reservoir. The investigation on thequantum correlation of the coupled qubits in squeezed vacuum reservoir show thatcontrolling the initial concurrence of coupled qubits and the purity of quantum statewill effectively suppress the damping of the quantum correlation between coupledqubits.