On non-Markovian time evolution in open quantum systems

TL;DR

This paper investigates non-Markovian dynamics in open quantum systems and introduces an approximation method to ensure the reduced dynamics remains completely positive when the reservoir starts in the vacuum state.

Contribution

It presents a novel approximation technique for non-Markovian open quantum systems that guarantees complete positivity of the reduced dynamics.

Findings

The approximation works for vacuum initial reservoir states.

It preserves complete positivity in non-Markovian evolution.

Provides a new tool for analyzing open quantum systems.

Abstract

Non-Markovian reduced dynamics of an open system is investigated. In the case the initial state of the reservoir is the vacuum state, an approximation is introduced which makes possible to construct a reduced dynamics which is completely positive.