Engineering Near-Infrared Two-Level Systems in Confined Alkali Vapors

TL;DR

This paper demonstrates a method to create a stable two-level atomic system in hot rubidium vapor confined in a tiny cell, enabling efficient near-infrared light interactions for quantum technologies.

Contribution

It introduces a novel confined vapor cell setup that isolates a two-level system at telecom wavelengths, advancing miniaturized quantum photonic devices.

Findings

Effective two-level system achieved in confined rubidium vapor

Suppression of optical pumping into uncoupled states

Potential for integrated quantum photonic applications

Abstract

We combined experimental and theoretical investigations of an effective two-level atomic system operating in the near-infrared telecom wavelength regime, realized using hot rubidium vapor confined within a sub-micron-thick cell. In this strongly confined geometry, atomic coherence is profoundly influenced by wall-induced relaxation arising from frequent atom-surface collisions. By analyzing both absorption and fluorescence spectra, we demonstrate that the optical response is dominated by a closed cycling transition, which effectively isolates the atomic dynamics to a two-level configuration despite the presence of multiple hyperfine states. This confinement-induced selection suppresses optical pumping into uncoupled states and enables robust, controllable light-matter interaction at telecom wavelengths within a miniature atomic platform. Our results establish a practical route to realizing near-infrared atomic two-level systems in compact vapor-cell devices, opening new opportunities for integrated quantum photonic technologies, including on-chip quantum memories, telecom-band frequency references, and scalable quantum information processing.