Observation of Pauli blocking in light scattering from quantum degenerate fermions

TL;DR

This study demonstrates Pauli blocking in light scattering from ultracold degenerate Fermi gases, confirming fundamental quantum statistical effects and opening pathways for advanced cooling and thermometry techniques.

Contribution

First experimental observation of Pauli blocking in light scattering from quantum degenerate fermions, validating key quantum statistical predictions.

Findings

Suppressed light scattering in degenerate Fermi gases compared to thermal gases

Increased light transmission due to Pauli blocking effects

Confirmation of fundamental quantum statistical behavior in optical response

Abstract

The Pauli exclusion principle forbids indistinguishable fermions to occupy the same quantum mechanical state. Its implications are profound and it for example accounts for the electronic shell structure of atoms. Here we perform measurements on the scattering of off-resonant light from ultracold gasses of fermionic atoms. For Fermi gases in the quantum degenerate regime, we observe a marked suppression in light scattering as compared to a similarly prepared thermal Bose gas. We attribute the observed increased transmission of light through the quantum degenerate Fermi gas to Pauli blocking, where Fermi-Dirac statistics causes atoms to occupy a large region of the momentum space limiting the number of accessible states for the scattered atom. Our work confirms a longstanding fundamental result in the theory of the optical response of quantum gases and is an important step towards novel cooling and thermometry mechanisms for degenerate Fermi gases.