Quantum evolution speed in the finite-temperature bosonic environment

We investigate the quantum evolution speed of a qubit in two kinds of finite-temperature environments. The first environment is a bosonic bath with Ohmic-like spectrum. It is found that the high temperature not only leads to the speed-up but also speed-down processes in the weak-coupling regime, which is different from the strong-coupling case where only exhibits speed-up process, and the effects of Ohmicity parameter of the bath on the quantum evolution speed are also different in the strong-coupling and weak-coupling regimes. Furthermore, we realize the controllable and stationary quantum evolution speed by applying the bang-bang pulse. For the second nonlinear bath, we study the quantum evolution speed of a qubit by resorting to the hierarchical equations of motion method beyond the Born-Markov approximation. It is shown that the performances of quantum evolution speed in weak-coupling and strong-coupling regimes are also different. In particular, the quantum evolution speed can be decelerated by the rise of temperature in the strong-coupling regime which is an anomalous phenomenon and contrary to the common recognition that quantum evolution speed always increases with the temperature.
Comment: 14 pages, 8 figures