The Collective Lamb Shift of a Nanoscale Atomic Vapour Layer within a Sapphire Cavity

TL;DR

This paper investigates the collective Lamb shift in a nanoscale potassium vapor layer within a sapphire cavity, revealing a density-dependent resonance shift and an unexpected thickness dependence, supported by a comprehensive optical model.

Contribution

It introduces a detailed model accounting for multiple reflections and uncovers a novel thickness dependence of the collective Lamb shift in nanoscale atomic vapors.

Findings

Observed a strong asymmetry in the transmission line shape.

Extracted a density-dependent collective Lamb shift.

Discovered an unexpected dependence of the shift on medium thickness.

Abstract

We measure the near-resonant transmission of light through a dense medium of potassium vapor confined in a cell with nanometer thickness in order to investigate the origin and validity of the collective Lamb-shift. A complete model including the multiple reflections in the nano-cell accurately reproduces the observed strong asymmetry of the line shape and allows extraction of a density dependent shift of the atomic resonance. We observe an additional, unexpected dependence of this shift with the thickness of the medium. This extra dependence demands further experimental and theoretical investigations.