Spin-squeezed atomic crystal

We propose a method to obtain a regular arrangement of two-level atoms in a three-dimensional optical lattice with unit filling, where all the atoms share internal state coherenceand metrologically useful quantum correlations. Such a spin-squeezed atomic crystal is obtained by adiabatically raising an optical lattice in an interacting two-component Bose-Einstein condensate. The scheme could be directly implemented on a microwave transition with state-of-the arttechniques and used in optical-lattice atomic clocks with bosonic atoms to strongly suppress thecollisional shift and benefit from the spins quantum correlations at the same time.