| We report a new measurement of the atomic recoil using atom interferometry and Bloch oscillations (BO) in a vertical accelerated optical lattice. Such a measurement yields to a determination of h/m (m is the mass of the atom) which can be used to obtain a value of the fine structure constant. The principle of the experiment is to coherently transfer as many recoils as possible to the atoms (i.e. to accelerate them) and to measure the final velocity distribution. In our experiment, the atoms are efficiently accelerated by means of N Bloch oscillations. The velocity selection and velocity measurement are done with Raman transitions. In this talk, we will present two measurements of α: a non interferometric one using two $\pi$ Raman pulses, and an interferometric measurement with the [π/2-π2]-BO-[π/2-π/2] pulses arrangement. This last method leads to a determination of the fine structure constant α with a relative uncertainty better than 5 ppb. |
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