Observation of spontaneous quantum fluctuations in photon absorption by atoms

TL;DR

This paper reports the first observation of spontaneous quantum fluctuations in photon absorption by rubidium atoms, revealing rich quantum behaviors through sub-shot noise spectral measurements.

Contribution

It introduces a novel measurement technique using sub-shot noise detection to observe quantum fluctuations in atom-light interactions that were previously unobserved.

Findings

Detection of fluctuations due to atomic transit, Rabi flopping, and Larmor precession.

Spectral analysis reveals quantum properties of both atoms and light.

Demonstrates the rich nature of spontaneous quantum noise in photon absorption.

Abstract

Fluctuations in light absorption by atoms are observed by applying laser light on rubidium atoms and measuring the transmitted light intensity fluctuations. These fluctuations are spontaneous noise, which are generic to photon atom interactions. By making use of the sub-shot noise random signal detection technology, we have measured the spectra at sub-shot noise levels to reveal their rich nature, which had previously been unobserved. The effects of atoms transiting the laser beam, Rabi flopping in the optical transitions and Larmor precession of the magnetic moment are observed in the spectra. The properties of the fluctuations reflect not only the quantum behavior of atoms, but also that of light.