Quantum-to-Classical Transition in Cavity Quantum Electrodynamics

TL;DR

This paper investigates the gradual transition from quantum to classical behavior in cavity QED systems by analyzing how increasing thermal occupation affects quantum signatures, providing insights into the crossover and methods to measure effective temperatures.

Contribution

It presents a detailed study of the quantum-to-classical crossover in cavity QED by gradually increasing thermal occupation and introduces techniques to extract effective cavity field temperatures.

Findings

Quantum signatures diminish as thermal occupation increases.

Effective cavity field temperatures can be extracted from spectroscopic and time-resolved measurements.

The quantum-to-classical transition occurs smoothly over a range of thermal energies.

Abstract

The quantum properties of electromagnetic, mechanical or other harmonic oscillators can be revealed by investigating their strong coherent coupling to a single quantum two level system in an approach known as cavity quantum electrodynamics (QED). At temperatures much lower than the characteristic energy level spacing the observation of vacuum Rabi oscillations or mode splittings with one or a few quanta asserts the quantum nature of the oscillator. Here, we study how the classical response of a cavity QED system emerges from the quantum one when its thermal occupation -- or effective temperature -- is raised gradually over 5 orders of magnitude. In this way we explore in detail the continuous quantum-to-classical crossover and demonstrate how to extract effective cavity field temperatures from both spectroscopic and time-resolved vacuum Rabi measurements.