# Non-Markovian processes in quantum theory

## TL;DR

This paper reviews the concept of non-Markovian processes in quantum dynamics, emphasizing their theoretical foundations, differences from Markovian models, and implications for modifications of quantum mechanics.

## Contribution

It introduces fundamental notions of non-Markovian quantum processes, highlighting their conceptual significance and recent developments in the context of quantum theory modifications.

## Key findings

- Clarifies the definition of non-Markovian processes in quantum systems.
- Discusses the role of memory effects in quantum dynamics.
- Explores the connection between non-Markovianity and quantum measurement modifications.

## Abstract

The study of quantum dynamics featuring memory effects has always been a topic of interest within the theory of open quantum system, which is concerned about providing useful conceptual and theoretical tools for the description of the reduced dynamics of a system interacting with an external environment. Definitions of non-Markovian processes have been introduced trying to capture the notion of memory effect by studying features of the quantum dynamical map providing the evolution of the system states, or changes in the distinguishability of the system states themselves. We introduce basic notions in the framework of open quantum systems, stressing in particular analogies and differences with models used for introducing modifications of quantum mechanics which should help in dealing with the measurement problem. We further discuss recent developments in the treatment of non-Markovian processes and their role in considering more general modifications of quantum mechanics.