Interference of diffusing photons and level crossing spectroscopy

TL;DR

This paper reveals a new interference effect in photon intensity fluctuations caused by atomic Zeeman degeneracy in highly scattering atomic gases, leading to measurable resonance phenomena influenced by magnetic fields.

Contribution

It introduces a novel interference effect specific to Zeeman-degenerate atoms in high optical depth gases, with analytical expressions for observable quantities.

Findings

Resonance peak in photon fluctuations as a function of magnetic field

Resonance width inversely proportional to optical depth b

Analytic formulas for physical quantities accessible experimentally

Abstract

We show that a new interference effect appears in the intensity fluctuations of photons multiply scattered by an atomic gas of large optical depth b. This interference occurs only for scattering atoms that are Zeeman degenerate and it leads to a deviation from the Rayleigh law. The fluctuations measured by their variance, display a resonance peak as a function of an applied magnetic field. The resonance width is proportional to the small factor 1/b. We derive closed analytic expressions for all these physical quantities which are directly accessible experimentally.