Spatially dependent electromagnetically induced transparency

TL;DR

This paper demonstrates spatially dependent electromagnetically induced transparency in cold rubidium atoms using structured light with azimuthal phase and polarisation variations, revealing phase-sensitive EIT effects.

Contribution

It introduces a novel phase-sensitive EIT system using structured light and magnetic fields, showing spatial modulation of transparency linked to phase and polarisation.

Findings

Azimuthal modulation of absorption profile observed.

Phase-dependent dark states lead to phase-sensitive transparency.

Magnetic field closes EIT transitions, enabling phase control.

Abstract

Recent years have seen vast progress in the generation and detection of structured light, with potential applications in high capacity optical data storage and continuous variable quantum technologies. Here we measure the transmission of structured light through cold rubidium atoms and observe regions of electromagnetically induced transparency (EIT). We use q-plates to generate a probe beam with azimuthally varying phase and polarisation structure, and its right and left circular polarisation components provide the probe and control of an EIT transition. We observe an azimuthal modulation of the absorption profile that is dictated by the phase and polarisation structure of the probe laser. Conventional EIT systems do not exhibit phase sensitivity. We show, however, that a weak transverse magnetic field closes the EIT transitions, thereby generating phase dependent dark states which in turn lead to phase dependent transparency, in agreement with our measurements.