Functionalized mm-scale vapor cells for alkali-metal spectroscopy and magnetometry

TL;DR

This paper presents micro-fabricated rubidium vapor cells with integrated temperature control, enabling miniaturized ultra-sensitive magnetometers with demonstrated 18 fT/Hz$^{1/2}$ sensitivity in low-frequency magnetic field detection.

Contribution

The work introduces a novel dual-chamber micro-fabricated vapor cell with integrated heating and temperature sensing, advancing miniaturized alkali-metal magnetometry technology.

Findings

Successful thermal control of alkali vapor density.

Correlation of temperature with vapor pressure and buffer gas.

Achieved ultra-sensitive zero-field magnetometry with 18 fT/Hz$^{1/2}$ sensitivity.

Abstract

We describe micro-fabricated rubidium vapor cells with integrated temperature-control functionality and demonstrate their suitability for use in miniaturized ultra-sensitive magnetometers. These functionalized vapor cells (FVCs) embody a dual-chamber design in low-conductivity silicon with anti-permeation coatings and micro-structured thin-film platinum surface traces as resistive heaters and temperature sensors. Thermal tests show our ability to control alkali metal distribution within the FVCs, ensuring a clean sensing chamber for optical measurements. Optical absorption spectroscopy is used to correlate the temperature readings with vapor density and to measure buffer gas pressure, of interest for optimizing sensitivity. Finally, we demonstrate zero-field resonance magnetometry with 18 fT/Hz$^{1/2}$ sensitivity in the 10 Hz to 100 Hz band, limited by laser noise and magnetic shield noise, which indicates that the functionalization does not introduce significant magnetic noise.