Multi-level cascaded electromagnetically induced transparency in cold atoms using an optical nanofibre interface

TL;DR

This paper demonstrates multilevel cascaded electromagnetically induced transparency in cold rubidium atoms interfaced with an optical nanofibre, enabling potential applications in quantum information processing and all-optical switching.

Contribution

It reports the first observation of multilevel cascaded EIT in a cold atom-nanofibre system using low-power probe and coupling beams, advancing quantum network technologies.

Findings

Multipeak transparency spectra observed in probe beam.

Potential for slowing multiple wavelengths and generating entangled beams.

All-optical switching demonstrated using EIT effect.

Abstract

Ultrathin optical fibres integrated into cold atom setups are proving to be ideal building blocks for atom-photon hybrid quantum networks. Such optical nanofibres (ONF) can be used for the demonstration of nonlinear optics and quantum interference phenomena in atomic media. Here, we report on the observation of multilevel cascaded electromagnetically induced transparency (EIT) using an optical nanofibre to interface cold $^{87}$Rb atoms through the intense evanescent fields that can be achieved at ultralow probe and coupling powers. Both the probe (at 780 nm) and the coupling (at 776 nm) beams propagate through the nanofibre. The observed multipeak transparency spectra of the probe beam could offer a method for simultaneously slowing down multiple wavelengths in an optical nanofibre or for generating ONF-guided entangled beams, showing the potential of such an atom-nanofibre system for quantum information. We also demonstrate all-optical-switching in the all fibred system using the obtained EIT effect.