Steady-State Discord Between Two Qubits Coupled Collectively to a Thermal Reservoir

Abstract

We study the dynamics of quantum discord between two qubits coupled collectively to a thermal reservoir. For comparison, we also consider the dynamics of quantum entanglement. It is shown that we can obtain a stable quantum discord induced by the thermal environment when the discord of the initial state is zero. The thermal environment can also induce a stable amplification of the initially prepared quantum discord for certain Xtype states. It is very valuable that the quantum discord is more resistant against the thermal environment than quantum entanglement. And, we have demonstrated that the sudden death of discord in a Markovian regime is impossible even at high temperature. It provides us a feasible way to create and protect quantum correlation in the case of a high-temperature thermal environment for various physical system such as trapped ions, quantum dots or Josephson junctions.

Quantum properties and dynamics ofXstates

“…These projectors are labelled by the term maximalcorrelation-direction measurement (MCDM). Moreover, in [33], an expression for discord in the case of b = c is derived. Here, we derive a very similar result, but for the slightly more general case in which b and c are not necessarily equal.…”

Population Dynamics of Excited Atoms in Dissipative Cavities

“…In other words, the atom will dissipate eventually its excitation energy into the lower state as the time tends to infinity. Therefore, how to trap the excited atom in dissipating environments is of great interest in researches of quantum many-body physics [15][16][17], quantum information processing [18] and quantum nonlinear optics [19]. In particular, the atomic spontaneous emission and the environment-induced dissipation inevitably lead to decoherence of quantum systems so that the population trapping of excited atoms is very fragile, which is undesirable in the above quantum physics researches.…”