Observing electromagnetically induced transparency (EIT) using tapered atomic cladded nanowaveguides in hot atomic vapor

Electromagnetically induced transparency (EIT) enables an otherwise opaque medium to become transparent and slows down light pulses, even trapping these light pulses inside the medium. It provides a robust platform for manipulating and preserving quantum optical signals, making it a powerful tool for quantum information processing and precision sensing. In this work, we demonstrate EIT on a fully integrated, chip-scale platform based on nanoscale atomic suspended waveguides (NASWAGs) surrounded by hot rubidium vapor. These structures provide submillimeter-scale interaction lengths and feature a tapered geometry that extends the optical mode into the surrounding vapor, increasing the atom-light interaction volume and reducing transit-time broadening. Combined with the strong spatial confinement of both probe and control beams, this enables efficient EIT with only a few micro Watts of control power. This represents a significant advance over standard nanophotonic platforms, where weak evanescent fields and short interaction times have previously prevented the observation of EIT.