Bloch oscillations of ultracold atoms:: A tool for a metrological determination of h/mRb -: art. no. 253001

We use Bloch oscillations in a horizontal moving standing wave to transfer a large number of photon recoils to atoms with a high efficiency (99.5% per cycle). By measuring the photon recoil of Rb-87, using velocity-selective Raman transitions to select a subrecoil velocity class and to measure the final accelerated velocity class, we have determined h/m(Rb) with a relative precision of 0.4 ppm. To exploit the high momentum transfer efficiency of our method, we are developing a vertical standing wave setup. This will allow us to measure h/m(Rb) better than 10(-8) and hence the fine structure constant alpha with an uncertainty close to the most accurate value coming from the (g-2) determination.