Author(s)

Jing Wang¹, Yunan Wu¹, Wenyu Ji^2*

¹School of Physics and Technology, University of Jinan, Jinan, China.
²College of Physics, Jilin University, Changchun, China.

Quantum speedup of an open quantum system can be induced by the non-Markovian effect of the environment. Although an environment with a higher degree of non-Markovianity may seem like it should cause a faster speed of quantum evolution, this seemingly intuitive thinking may not always be correct. To clarify this point, we give a mechanism for controlling speedup of a single qubit that is coupled to a hierarchical photonic-crystal (PC) environment, which contains a defect single-mode cavity and a semi-infinite one-dimensional (1D) waveguide. Via studying the dynamics of the qubit, we reveal that with a judicious choice of the qubit-cavity coupling strength and the memory time of the waveguide environment, a speed-up evolution can be achieved. In particular, we found that the quantum speedup is not entirely attributed to the non-Markovianity, but to the increase of the total amount of flow information. That is the intrinsic physical reason that the hierarchical environment may induce the speed-up process. Our results may open new perspectives for detecting quantum speedup in realistic environments.

Non-Markovianity, Quantum Speed Limit Time, Photonic Crystal

Wang, J. , Wu, Y. and Ji, W. (2019) Controlling Speedup Induced by a Hierarchical Environment. Journal of Modern Physics, 10, 1177-1189. doi: 10.4236/jmp.2019.1010078.