Polarization-driven spin precession of mesospheric sodium atoms

TL;DR

This paper presents the first on-sky observation of mesospheric sodium atom spin precession driven by laser polarization modulation, demonstrating remote detection of magnetic resonance in the mesosphere.

Contribution

It introduces a novel experimental method for observing atomic spin precession in the mesosphere using polarization-modulated laser light and ground-based fluorescence detection.

Findings

Successful detection of sodium atom spin precession at 85-100 km altitude.

Measured Larmor frequency with 0.4 mG geomagnetic field error.

Results align with geomagnetic models and light-atom interaction theory.

Abstract

We report experimental results on the first on-sky observation of atomic spin precession of mesospheric sodium driven by polarization modulation of a continuous-wave laser. The magnetic resonance was remotely detected from the ground by observing the enhancement of induced fluorescence when the driving frequency approached the precession frequency of sodium in the mesosphere, between 85 km and 100 km altitude. The experiment was performed at La Palma, and the uncertainty in the measured Larmor frequency ($\approx$260 kHz) corresponded to an error in the geomagnetic field of 0.4 mG. The results are consistent with geomagnetic field models and with the theory of light-atom interaction in the mesosphere.