title: Quantum speed limits in open systems: non-Markovian dynamics without rotating-wave approximation.
abstract: We derive an easily computable quantum speed limit (QSL) time bound for open systems whose initial states can be chosen as either pure or mixed states. Moreover, this QSL time is applicable to either Markovian or non-Markovian dynamics. By using of a hierarchy equation method, we numerically study the QSL time bound in a qubit system interacting with a single broadened cavity mode without rotating-wave, Born and Markovian approximation. By comparing with rotating-wave approximation (RWA) results, we show that the counter-rotating terms are helpful to increase evolution speed. The problem of non-Markovianity is also considered. We find that for non-RWA cases, increasing system-bath coupling can not always enhance the non-Markovianity, which is qualitatively different from the results with RWA. When considering the relation between QSL and non-Markovianity, we find that for small broadening widths of the cavity mode, non-Markovianity can increase the evolution speed in either RWA or non-RWA cases, while, for larger broadening widths, it is not true for non-RWA cases.
authors: 1] Department of Physics, Hangzhou Normal University, Hangzhou 310036, China [2] Department of Physics, National University of Singapore, Singapore 117542 [3] Singapore University of Technology and Design, 20 Dover Drive 138682, Singapore.
authors: Zhe
authors: Z
authors: Sun
authors: Zhejiang Institute of Modern Physics, Department of Physics, Zhejiang University, Hangzhou 310027, China.
authors: Jing
authors: J
authors: Liu
authors: Zhejiang Institute of Modern Physics, Department of Physics, Zhejiang University, Hangzhou 310027, China.
authors: Jian
authors: J
authors: Ma
authors: Zhejiang Institute of Modern Physics, Department of Physics, Zhejiang University, Hangzhou 310027, China.
authors: Xiaoguang
authors: X
authors: Wang