Effects of temperature and ground-state coherence decay on enhancement and amplification in a $\Delta$ atomic system

TL;DR

This paper investigates how temperature and ground-state coherence decay influence phase-sensitive amplification in a Delta atomic system, demonstrating robustness of electromagnetically induced transparency and conditions for probe amplification.

Contribution

It provides a theoretical analysis of EIT enhancement and amplification in a Delta system considering temperature and coherence decay effects, revealing conditions for probe amplification at any temperature.

Findings

EIT enhancement is robust against ground-state coherence loss.

A threshold decay rate determines probe amplification vs attenuation.

Amplification is achievable at any temperature in the Delta system.

Abstract

We study phase-sensitive amplification of electromagnetically induced transparency in a warm ${}^{85}$Rb vapor wherein a microwave driving field couples the two lower-energy states of a {\Lambda} energy-level system thereby transforming into a {\Delta} system. Our theoretical description includes effects of ground-state coherence decay and temperature effects. In particular, we demonstrate that driving-field-enhanced electromagnetically induced transparency is robust against significant loss of coherence between ground states. We also show that for specific field intensities, a threshold rate of ground-state coherence decay exists at every temperature. This threshold separates the probe-transmittance behavior into two regimes: probe amplification vs probe attenuation. Thus, electromagnetically induced transparency plus amplification is possible at any temperature in a {\Delta} system.