Precise determination of h/m_Rb using Bloch oscillations and atomic interferometry: a mean to deduce the fine structure constant

TL;DR

This paper presents precise measurements of the h/m_Rb ratio using Bloch oscillations and atomic interferometry to accurately determine the fine structure constant alpha, achieving uncertainties at the parts-per-billion level.

Contribution

It introduces a novel combination of Bloch oscillations and atomic interferometry for highly precise determination of h/m_Rb and alpha.

Findings

Measured alpha^{-1} = 137.03599884(91) with 6.6 ppb uncertainty

Demonstrated atomic interferometry as a viable method for precise alpha measurement

Achieved initial results with new interferometric approach

Abstract

We use Bloch oscillations to transfer coherently many photon momenta to atoms. Then we can measure accurately the ratio h/m_Rb and deduce the fine structure constant alpha. The velocity variation due to the Bloch oscillations is measured thanks to Raman transitions. In a first experiment, two Raman $\pi$ pulses are used to select and measure a very narrow velocity class. This method yields to a value of the fine structure constant alpha^{-1}= 137.035 998 84 (91) with a relative uncertainty of about 6.6 ppb. More recently we use an atomic interferometer consisting in two pairs of pi/2 pulses. We present here the first results obtained with this method.