Saïda Guellati-Khélifa

Determination of the fine structure constant based on bloch oscillations of ultracold atoms in a vertical optical lattice

We report an accurate measurement of the recoil velocity of 87Rb atoms based on Bloch oscillations in a vertical accelerated optical lattice. We transfer about 900 recoil momenta with an efficiency of 99.97% per recoil. A set of 72 measurements of the recoil velocity, each one with a relative uncertainty of about 33 ppb in 20 min integration time, leads to a determination of the fine structure constant with a statistical relative uncertainty of 4.4 ppb. The detailed analysis of the different systematic errors yields to a relative uncertainty of 6.7 ppb. The deduced value of alpha-1 is 137.035 998 78(91).

Combination of Bloch oscillations with a Ramsey-Borde 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) =137.03599945 (62) with a relative uncertainty of 4.6 x 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.

Bloch Oscillations of Ultracold Atoms: A Tool for a Metrological Determination of h/m~R~b

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 87Rb, 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.

A promising method for the measurement of the local acceleration of gravity using Bloch oscillations of ultracold atoms in a vertical standing wave

An obvious determination of the local acceleration of gravity g can be deduced from the measurement of the velocity of falling atoms using a π-π pulses sequence of stimulated Raman transitions. By using a vertical standing wave to hold atoms against gravity, we expect to improve the relative accuracy by increasing the upholding time in the gravity field and to minimize the systematic errors induced by inhomogeneous fields, owing to the very small spatial amplitude of the atomic center-of-mass wavepacket periodic motion. We also propose to use such an experimental setup nearby a Watt balance. By exploiting the g/h (h is the Planck constant) dependence of the Bloch frequency, this should provide a way to link a macroscopic mass to an atomic mass.

Compact atomic gravimeter based on a pulsed and accelerated optical lattice

We present a new scheme of compact atomic gravimeter based on atom interferometry. Atoms are maintained against gravity using a sequence of coherent accelerations performed by the Bloch oscillations technique. We demonstrate a sensitivity of 4.8

Acceleration of ultracold atoms: towards a measurement of h/MRb

\times 10^{-8}

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

with an integration time of 4 min. Combining this method with an atomic elevator allows to measure the local gravity at different positions in the vacuum chamber. This method can be of relevance to improve the measurement of the Newtonian gravitational constant

Precise determination of the ratio h/m u: a way to link microscopic mass to the new kilogram

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Comment refroidir les atomes froids avec la lumière laser ? Principes et techniques

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Determination of the fine structure constant with atom interferometry and Bloch oscillations on 87 Rb atoms

We develop here the principle of an experiment whose purpose is the measurement of the atomic recoil velocity. The ratio h/MX, where h is the Planck constant and MX the atomic mass, and then the fine structure constant α, can be deduced from this measurement. A high precision measurement of the recoil velocity should lead to a determination of α of metrological interest.