# Electric current in a translation invariant environment

## TL;DR

This paper analyzes how a translation invariant environment affects the electric current of a charged particle, revealing environment signatures in bremsstrahlung and examining wave packet decoherence.

## Contribution

It provides a general solution for the reduced density matrix without external fields and highlights the impact of boundary conditions on system behavior.

## Key findings

- Electric current is renormalized by environment interactions.
- Bremsstrahlung signatures reflect environment effects.
- Wave packet spread and decoherence are characterized.

## Abstract

The master equation for the reduced density matrix of a charged particle interacting with a translation invariant weakly coupled environment is considered. The electric current is renormalized by the system-environment interaction, leading to a direct signature of the environment in the bremsstrahlung. The general solution is given in the absence of the external electromagnetic field and the spread and the decoherence of a wave packet are followed. The increased complexity and importance of the boundary conditions for the density matrix are pointed out.