Decoherence of a charged Brownian particle in a magnetic field : an analysis of the roles of coupling via position and momentum variables

TL;DR

This paper investigates how a charged quantum particle's decoherence is affected by both position and momentum couplings to an environment in a magnetic field, revealing faster decoherence with combined couplings and magnetic field effects that slow information loss.

Contribution

It provides a comprehensive analysis of decoherence dynamics considering both position and momentum couplings in a magnetic field, extending previous models.

Findings

Combined couplings lead to faster decoherence.

Magnetic field slows down the decoherence process.

Decoherence rate can be controlled via coupling strengths.

Abstract

The study of decoherence plays a key role in our understanding of the transition from the quantum to the classical world. Typically, one considers a system coupled to an external bath which forms a model for an open quantum system. While most of the studies pertain to a position coupling between the system and the environment, some involve a momentum coupling, giving rise to an anomalous diffusive model. Here we have gone beyond existing studies and analysed the quantum Langevin dynamics of a harmonically oscillating charged Brownian particle in the presence of a magnetic field and coupled to an Ohmic heat bath via both position and momentum couplings. The presence of both position and momentum couplings leads to a stronger interaction with the environment, resulting in a faster loss of coherence compared to a situation where only position coupling is present. The rate of decoherence can be tuned by controlling the relative strengths of the position and momentum coupling parameters. In addition, the magnetic field results in the slowing down of the loss of information from the system, irrespective of the nature of coupling between the system and the bath. Our results can be experimentally verified by designing a suitable ion trap setup.