Tuning quantum discord in Josephson charge qubits system
  A type of two qubits Josephson charge system is constructed in this paper, and properties of the quantum discord (QD) as well as the differences between thermal QD and thermal entanglement were investigated. A detailed calculation shows that the magnetic flux $\Phi_{Xk}$ is more efficient than the voltage $V_{Xi}$ in tuning QD. By choosing proper system parameters, one can realize the maximum QD in our two qubits Josephson charge system. 
Bo-xing Shang and Xi-qiang Xi
quant-ph