Fixing semi-classical physics from first principles: how to derive effective classical-quantum dynamics from open quantum theory

TL;DR

This paper demonstrates how incorporating environmental decoherence into semi-classical models can produce accurate effective classical-quantum dynamics derived from open quantum theory.

Contribution

It introduces a method to derive consistent classical-quantum models from open quantum systems by including decoherence effects, improving upon standard mean-field approaches.

Findings

Standard semi-classical approaches can fail to accurately describe quantum dynamics.

Including environmental decoherence improves the accuracy of semi-classical models.

Effective classical-quantum dynamics can be rigorously derived from open quantum theory.

Abstract

Semi-classical approaches approximate fully quantum descriptions with partially classical ones. Here we use a toy model to highlight the failings of the standard mean-field semi-classical approach, and show how including environmental decoherence can lead to improved semi-classical theories that are exact descriptions of the original quantum dynamics. In doing so, we show how consistent models of classical-quantum dynamics can arise as effective descriptions of open quantum systems.