Efficient optical pumping of alkaline atoms for evanescent fields at dielectric-vapor interfaces

TL;DR

This paper demonstrates highly efficient hyperfine optical pumping of rubidium atoms at a dielectric-vapor interface using evanescent fields, advancing nanoscale light-atom interaction control for quantum technologies.

Contribution

It introduces a novel on-chip method for optical pumping at the nanoscale with potential applications in quantum devices.

Findings

Complete suppression of absorption on the evanescent signal.

Efficient optical pumping achieved with normal incidence pump laser.

Model based on optical Bloch equations supports experimental results.

Abstract

We experimentally demonstrate hyperfine optical pumping of rubidium atoms probed by an evanescent electromagnetic field at a dielectric-vapor interface. This light-atom interaction at the nanoscale is investigated using a right angle prism integrated with a vapor cell and excited by evanescent wave under total internal reflection. An efficient hyperfine optical pumping, leading to a complete suppression of absorption on the probed evanescent signal, is observed when a pump laser beam is sent at normal incidence to the interface. In contrast, when the pump and probe beams are co-propagating in the integrated prism-vapor cell, no clear evidence of optical pumping is observed. The experimental results are supported by a detailed model based on optical Bloch equation of a four atomic levels structure. The obtained on-chip highly efficient optical pumping at the nanoscale is regarded as an important step in the quest for applications such as optical switching, magnetometry and quantum memory.