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 $h/m_{\mathrm{Rb}}$. 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 $h/m_{\mathrm{Rb}}$ leads to a new determination of the fine structure constant ${\alpha }^{-1}=137.03599945(62)$ with a relative uncertainty of $4.6\times {10}^{-9}$. The comparison of this result with the value deduced from the measurement of the electron anomaly provides the most stringent test of QED.