# Non-Markovian evolution of multi-level system interacting with several reservoirs. Exact and approximate

## TL;DR

This paper presents an exactly solvable model for multi-level quantum systems interacting with multiple reservoirs at zero temperature, comparing exact and approximate decay and decoherence rates.

## Contribution

It introduces a solvable model and systematically compares exact solutions with common approximate master equations for multi-reservoir interactions.

## Key findings

- Exact and approximate rates are quantitatively compared.
- Parameter space is classified based on discrepancies between exact and approximate rates.
- Insights into the validity of approximate methods in different regimes.

## Abstract

An exactly solvable model for the multi-level system interacting with several reservoirs at zero temperatures is presented. Population decay rates and decoherence rates predicted by exact solution and several approximate master equations, which are widespread in physical literature, are compared. The space of parameters is classified with respect to different inequities between the exact and approximate rates.