Tuning of the Hanle effect from EIT to EIA using spatially separated probe and control beams

TL;DR

This paper presents a method to continuously tune the Hanle effect from EIT to EIA by adjusting the polarization ellipticity of a control beam, using spatially separated beams in a room temperature vapor cell, with applications in quantum memory.

Contribution

It introduces a novel technique for tuning the Hanle effect from EIT to EIA using spatially separated probe and control beams, supported by a density-matrix analysis.

Findings

Successful demonstration of continuous Hanle effect tuning.

Agreement between experimental results and density-matrix model.

Potential applications in quantum memory and precision measurements.

Abstract

We demonstrate a technique for continuous tuning of the Hanle effect from electromagnetically induced transparency (EIT) to electromagnetically induced absorption (EIA) by changing the polarization ellipticity of a control beam. In contrast to previous work in this field, we use spatially separated probe and control beams. The experiments are done using magnetic sublevels of the $ F_g = 4 \rightarrow F_e = 5 $ closed hyperfine transition in the 852 nm D$_2$ line of $^{133}$Cs. The atoms are contained in a room temperature vapor cell with anti-relaxation (paraffin) coating on the walls. The paraffin coating is necessary for the atomic coherence to be transported between the beams. The experimental results are supported by a density-matrix analysis of the system, which also explains the observed amplitude and zero-crossing of the resonances. Such continuous tuning of the sign of a resonance has important applications in quantum memory and other precision measurements.