Decoherence-free dynamics of quantum discord for two correlated qubits   in finite-temperature reservoirs
  We investigate decoherence-free evolution (DFE) of quantum discord (QD) for two initially-correlated qubits in two finite-temperature reservoirs using an exactly solvable model. We study QD dynamics of the two qubits coupled to two independent Ohmic reservoirs when the two qubits are initially prepared in X-type quantum states. It is found that reservoir temperature significantly affects the DFE dynamics. We show that it is possible to control the DFE and to prolong the DFE time by choosing suitable parameters of the two-qubit system and reservoirs. 
Lan Xu, Ji-Bing Yuan, Qing-Shou Tan, Lan Zhou, and Le-Man Kuang
quant-ph