Cold Atoms in Bordeaux

The project ALCALINF aims at developing a very long baseline atom interferometer operating with alkali-earth atomic species. The interferometer will use a single photon optical transition to split, deflect and project the atomic wavefunction. The scheme will grant a high degree of immunity to the laser frequency and phase noise that arises in 2-photon beam splitters for large wavepackets/atomic ensembles separations. ALCALINF will develop an important technique to make feasible gravitational wave detection based on atom interferometry, and constitutes then an important potential upgrade for MIGA. The final target is to explore atom interferometry in an unprecedented parameter range, and study for example the relativistic correction arising from the light travel time between the wavepackets during the atom-light interaction. In the short term, we are realizing a 6 m tall atomic fountain for ultra-cold strontium atoms, to implement gravity and gravity-gradient measurements.