Ultracold molecules: new probes on the variation of fundamental constants

TL;DR

This paper reviews how ultracold molecules can be used as highly sensitive probes to detect potential variations in fundamental constants, summarizing theoretical background, current constraints, and proposing new spectroscopic methods.

Contribution

It introduces two novel spectroscopic schemes with enhanced sensitivity for measuring variations in fundamental constants using ultracold molecules.

Findings

Summarizes current constraints on fundamental constant variations.

Proposes resonant scattering near Feshbach resonances as a sensitive probe.

Suggests spectroscopy on close-lying energy levels for improved detection.

Abstract

Ultracold molecules offer brand new opportunities to probe the variation of fundamental constants with unprecedented sensitivity. This paper summarizes theoretical background and current constraints on the variation of fine structure constant and electron-to-proton mass ratio, as well as proposals and experimental efforts to measure the variations based on ultracold molecules. In particular, we describe two novel spectroscopic schemes on ultracold molecules which have greatly enhanced sensitivity to fundamental constants: resonant scattering near Feshbach resonances and spectroscopy on close-lying energy levels of ultracold molecules.