The classical limit of quantum optics: not what it seems at first sight

TL;DR

This paper explores the complex relationship between quantum optics and classical theories, revealing that the classical limit of quantum optics is more intricate than traditionally thought, necessitating a fundamental revision of our intuitions.

Contribution

It demonstrates that understanding the classical limit of quantum optics requires a comprehensive reevaluation of existing assumptions, challenging the notion that this transition is straightforward.

Findings

The classical limit of quantum optics is more complex than previously assumed.

Traditional intuitions about the quantum-classical transition need revision.

Revised understanding can guide the discovery of new quantum effects.

Abstract

What is light and how to describe it has always been a central subject in physics. As our understanding has increased, so have our theories changed: Geometrical optics, wave optics and quantum optics are increasingly sophisticated descriptions, each referring to a larger class of phenomena than its predecessor. But how exactly are these theories related? How and when wave optics reduces to geometric optics is a rather simple problem. Similarly, how quantum optics reduces to wave optics has been considered to be a very simple business as well. It's not so. As we show here the classical limit of quantum optics is a far more complicated issue; it is in fact dramatically more involved and it requires a complete revision of all our intuitions. The revised intuitions can then serve as a guide to finding novel quantum effects.