Universal quantum correlation close to quantum critical phenomena

Quantum correlation of qubit-reservoir system in dissipative environments

In this work, the dynamics of quantum correlation (QC) in terms of geometric discord and its transfer coupled with dissipative reservoirs are investigated. Taken two canonical cases where the qubits of interest are initially prepared in extended Werner-like state and W-like states into account, we specifically reveal the dynamical behaviors of the geometric discord as each qubit locally interacts with its surrounding infinite degree-of-freedom reservoir. In the scenarios, the short-term and long-term dynamics of the geometric discord for the qubit- and reservoir-subsystem as well as its transfers between them are observed detailedly. It turns out that the geometric discord of qubit-subsystem decays asymptotically to zero while the counterpart of reservoir-subsystem can revive from time t = 0 to steady value, which sheds light on a transfer of the discord from the qubit-subsystem to the corresponding reservoir-subsystem.

Finite-temperature scaling of trace distance discord near criticality in spin diamond structure

In this work we explore the quantum correlation quantified by trace distance discord as a measure to analyze the quantum critical behaviors in the Ising-XXZ diamond structure at finite temperatures. It is found that the first-order derivative of the trace distance discord exhibits a maximum around the critical point at finite temperatures. By analyzing the finite-temperature scaling behavior, we show that such a quantum correlation can detect exactly the quantum phase transitions from the entan-gled state in ferrimagnetic phase to an unentangled state in ferrimagnetic phase or to an unentangled state in ferromagnetic phase. The results also indicate that the above two kinds of transitions can be distinguished by the different finite-temperature scaling behaviors. Moreover, we find that the trace distance discord, in contrast to other typical quantum correlations (e.g., concurrence, quantum discord and Hellinger distance), may be more reliable to exactly spotlight the critical points of this model at finite temperatures under certain situations.