Quantum speedup in a memory environment

Memory (non-Markovian) effect is found to be able to accelerate quantum evolution [S. Deffner and E. Lutz, Phys. Rev. Lett. 111, 010402 (2013).]. In this work, for an atom in a structured reservoir, we show that the mechanism for the speedup is not only related to non-Markovianity but also to the population of excited states under a given driving time. In other words, it is the competition between non-Markovianity and population of excited states that ultimately determines the acceleration of quantum evolution in memory environments. A potential experimental realization for verifying the above phenomena is discussed by using a nitrogen-vacancy center embedded in a planar photonic crystal cavity under current technologies.