# Role of non-Markovianity and backflow of information in the speed of quantum evolution

## TL;DR

This paper investigates how non-Markovian effects and information backflow influence the initial speed of quantum evolution in open quantum systems, showing speed increases are linked to environmental information returning to the system.

## Contribution

It demonstrates that in certain quantum models, the initial evolution speed correlates with non-Markovianity and backflow of information, highlighting their role in quantum dynamics.

## Key findings

- Speed increases only occur with information backflow.
- Initial speed is a monotonic function of non-Markovianity.
- Backflow of information is necessary for speed enhancement.

## Abstract

We consider a two-level open quantum system undergoing either pure dephasing, dissipative, or multiply decohering dynamics and show that, whenever the dynamics is non-Markovian, the initial speed of evolution is a monotonic function of the relevant physical parameter driving the transition between the Markovian and non-Markovian behaviour of the dynamics. In particular, within the considered models, a speed increase can only be observed in the presence of backflow of information from the environment to the system.