Measurement of a magic-zero wavelength

TL;DR

This paper reports a precise measurement of the magic-zero wavelength for ground state potassium atoms, providing a benchmark for atomic theory and demonstrating a new application for atom interferometry.

Contribution

The paper presents the longest measured magic-zero wavelength for potassium and uses it to improve atomic structure calculations and explore interferometry applications.

Findings

Measured $ ext{λ}_ ext{zero}$ as 768.971(1) nm for potassium

Determined the D1/D2 line strength ratio with record precision

Discussed decoherence limits in future magic-zero wavelength measurements

Abstract

Light at a magic-zero wavelength causes zero energy shift for an atom. We measured the longest magic-zero wavelength for ground state potassium atoms to be $\lambda_\textrm{zero}=768.971(1)$ nm, and we show how this provides an improved experimental benchmark for atomic structure calculations. This $\lambda_\textrm{zero}$ measurement determines the ratio of the potassium atom D1 and D2 line strengths with record precision. It also demonstrates a new application for atom interferometry, and we discuss how decoherence will fundamentally limit future measurements of magic-zero wavelengths.