Transition linewidth of cross-correlations in random intensity fluctuations in EIT

TL;DR

This paper investigates the linewidth of the correlation-anticorrelation transition in EIT, showing it can be narrower than the coherence lifetime limit and depends on laser parameters, with experimental validation.

Contribution

It introduces a numerical model for the transition linewidth in EIT and experimentally confirms the model's predictions, highlighting the influence of laser linewidth and power.

Findings

Linewidth is below the coherence lifetime limit.

Transition linewidth depends on laser linewidth and power.

Experimental results qualitatively agree with the model.

Abstract

It is known that cross-correlation between the random intensity fluctuations of two lasers forming electromagnetically-induced transparency (EIT) exhibits a transition from correlation to anticorrelation. We study the linewidth behavior of this transition and have found the linewidth is below the (effective) coherence lifetime limit and is only limited by competing noises. We established a numerical model which reveals the linewidth dependence on laser linewidth and laser power. Our experiments using lasers with different linewidth showed results in qualitative agreement with the model. This result is useful for quantum optics using EIT, and may also have applications in spectroscopy and precision measurements.