A Precise Determination of the Fine Structure Constant

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

We use Bloch oscillations to transfer coherently many photon momenta to atoms. Then we can measure accurately the ratio h/mRb and deduce the fine structure constant α. The velocity variation due to the Bloch oscillations is measured thanks to Raman transitions. In a first experiment, two Raman π pulses are used to select and measure a very narrow velocity class. This method yields to a value of...

A new photon recoil experiment: towards a determination of the fine structure constant

We report on progress towards a measurement of the fine structure constant α to an accuracy of 5 × 10 or better by measuring the ratio h/mCs of the Planck constant h to the mass of the cesium atom mCs. Compared to similar experiments, ours is improved in three significant ways: (i) simultaneous conjugate interferometers, (ii) multi-photon Bragg diffraction between same internal states, and (iii...

The Meaning of the Fine Structure Constant

Combination of BLOCH oscillations with a Ramsey-Bordé interferometer: new determination of the fine structure constant.

We report a new experimental scheme which combines atom interferometry with Bloch oscillations to provide a new measurement of the ratio h/mRb. By using Bloch oscillations, we impart to the atoms up to 1600 recoil momenta and thus we improve the accuracy on the recoil velocity measurement. The deduced value of h/mRb leads to a new determination of the fine structure constant alpha(-1) =137.0359...

Time Evolution of the Fine Structure Constant

We present a short review of the current quasar (QSO) absorption line constraints on possible variation of the fine structure constant, α ≡ e 2 /¯ hc. Particular attention is paid to recent optical Keck/HIRES spectra of 49 absorption systems which indicate a smaller α in the past [1, 2]. Here we present new preliminary results from 128 absorption systems: ∆α/α = (−0.57 ± 0.10) × 10 −5 over the ...