Photon lifetime in a cavity containing a slow-light medium

TL;DR

This study experimentally demonstrates that the photon lifetime in a cavity with a slow-light medium is primarily determined by the group velocity of light, not its phase velocity, using EIT in helium gas.

Contribution

It provides the first experimental evidence linking photon lifetime in a cavity to the group velocity in a slow-light medium.

Findings

Photon lifetime correlates with group velocity.

EIT medium enables slow light at room temperature.

Photon lifetime is governed by group velocity, not phase velocity.

Abstract

We investigate experimentally the lifetime of the photons in a cavity containing a medium exhibiting strong positive dispersion. This intracavity positive dispersion is provided by a metastable helium gas at room temperature in the electromagnetically induced transparency (EIT) regime, in which light propagates at a group velocity of the order of 10000 m/s. The results definitely prove that the lifetime of the cavity photons is governed by the group velocity of light in the cavity, and not its phase velocity.