Atom interferometers are powerful tools that allow for precise and accurate measurements of inertial forces and electromagnetic interactions. These devices are currently limited by the fundamental atom shot noise , where the relative statistical uncertainty is given by 1/√N , where N is the atom number. The performance of atom interferometers can be greatly improved by implementing a source of correlated squeezed atomic states, potentially reaching the Heisenberg limit, where the relative uncertainty is 1/N .
Accurate measurements also require that systematic effects are well under control.
In my talk I will present our results on atom interferometers based on Bragg diffraction of strontium atoms and show that these devices can limit many systematic effects in precision measurements . I will then show that the presence of narrow intercombination lines in strontium allows for the production of correlated atomic states with a reduced quantum uncertainty of up to 20 dB. Our method is based on collective measurements of the populations of the interferometer states. The main technological challenges will be discussed in view of state-of-the-art atom interferometers and a suitable experimental setup will be presented.
 G. Rosi, F. Sorrentino, L. Cacciapuoti, M. Prevedelli and G. M. Tino, Nature, 510, 518-521 (2014)
 T. Mazzoni, X. Zhang, R. Del Aguila, L. Salvi, N. Poli and G. M. Tino, Phys. Rev. A 92, 053619 (2015)