Time-resolved physical spectrum in cavity quantum electrodynamics

TL;DR

This paper theoretically investigates the time-resolved physical spectrum in cavity quantum electrodynamics, emphasizing the role of causality and correlation functions in understanding transient spectral features like Rabi oscillations and Fano anti-resonance.

Contribution

It introduces a theoretical framework for analyzing the time-resolved spectrum considering causality, revealing new insights into transient phenomena in cavity QED systems.

Findings

Rabi doublet cannot appear during the first peak of Rabi oscillation

Causality influences the transient magnitude of the Rabi doublet

Differences between Rabi doublet and Fano anti-resonance are highlighted

Abstract

The time-resolved physical spectrum of luminescence is theoretically studied for a standard cavity quantum electrodynamics system. In contrast to the power spectrum for the steady state, the correlation functions up to the present time are crucial for the construction of the time-resolved spectrum, while the correlations with future quantities are inaccessible because of the causality, i.e., the future quantities cannot be measured until the future comes. We find that this causality plays a key role to understand the time-resolved spectrum, in which the Rabi doublet can never be seen during the time of the first peak of the Rabi oscillation. Furthermore, the causality can influence on the transient magnitude of the Rabi doublet in some situations. We also study the dynamics of the Fano anti-resonance, where the difference from the Rabi doublet can be highlighted.