Nonlinear quantum atom optics squeezing and interferometry

The main part of the talk will be devoted to the results on generation of 8.3dB spin squeezing with this system. The high level of experimental control leads to an almost Heisenberg limited squeezed state which implies strong many particle entanglement. Employing the entanglement witness for the depth of entanglement developed by Sorenson and Molmer one can claim that at least 80 particles out of 400 are entangled within three sigma confidence level. With this massive quantum resource it was possible to demonstrate explicitly the improvement of a Ramsey type matterwave interferometer beyond the classical precision limit. Since the squeezing is realize within the first beamsplitter of the interferometer while the input state is a classical coherent state we refer to this setup as nonlinear matterwave interferometer.