Super-extended nanofiber-guided field for coherent interaction with hot atoms

TL;DR

This paper introduces a novel ultra-thin optical fiber with a super-extended mode that enables efficient, long-range, and coherent light-atom interactions at the single-photon level, suitable for quantum non-linear optics.

Contribution

It presents the fabrication and characterization of a super-extended nanofiber guiding mode that combines strong confinement with long interaction lengths for hot atomic vapors.

Findings

Achieved narrow electromagnetically induced transparency resonances at the single-photon level.

Demonstrated long atomic relaxation times of 10 ns with guided light.

Mode dimensions are compatible with Rydberg blockade, enabling quantum non-linear optics.

Abstract

We fabricate an extremely thin optical fiber that supports a super-extended mode with a diameter as large as 13 times the optical wavelength, residing almost entirely outside the fiber and guided over thousands of wavelengths (5 mm), in order to couple guided light to warm atomic vapor. This unique configuration balances between strong confinement, as evident by saturation powers as low as tens of nW, and long interaction times with the thermal atoms, thereby enabling fast and coherent interactions. We demonstrate narrow coherent resonances (tens of MHz) of electromagnetically induced transparency for signals at the single-photon level and long relaxation times (10 ns) of atoms excited by the guided mode. The dimensions of the guided mode's evanescent field are compatible with the Rydberg blockade mechanism, making this platform particularly suitable for observing quantum non-linear optics phenomena.