Decoherence and Dissipation for a Quantum System Coupled to a Local Environment

TL;DR

This paper investigates how quantum systems interact with local environments, focusing on decoherence and dissipation, and compares different models including first-principles calculations and phenomenological approaches.

Contribution

It analyzes the characteristics of quantum Brownian motion in local environments and compares various theoretical models with standard results.

Findings

Effective quantum Langevin and master equations derived

Comparison with Caldeira-Leggett model shows differences

Highlights importance of environment spatial correlations

Abstract

Decoherence and dissipation in quantum systems has been studied extensively in the context of Quantum Brownian Motion. Effective decoherence in coarse grained quantum systems has been a central issue in recent efforts by Zurek and by Hartle and Gell-Mann to address the Quantum Measurement Problem. Although these models can yield very general classical phenomenology, they are incapable of reproducing relevant characteristics expected of a local environment on a quantum system, such as the characteristic dependence of decoherence on environment spatial correlations. I discuss the characteristics of Quantum Brownian Motion in a local environment by examining aspects of first principle calculations and by the construction of phenomenological models. Effective quantum Langevin equations and master equations are presented in a variety of representations. Comparisons are made with standard results such as the Caldeira-Leggett master equation.