Spin squeezing and entanglement in atomic Bose-Einstein condensates

Ferromagnetic spin-1 condensates provide an interesting system for exploring nonlinear dynamical behavior near a second-order phase transition. Bose-Einstein condensates of spin-1 species, including rubidium-87, have for this reason been used to study the complex physics occurring near the quantum critical point that lies between the two distinct quantum phases. Moreover, the dynamics near the phase transition have been used to generate quantum entanglement, including Gaussian and non-Gaussian spin squeezing, using both adiabatic and non-adiabatic methods. We present new experimental results showing highly entangled states using a novel control technique exploiting the full hyperfine manifold in rubidium. We compare our results with both semi-classical and fully quantum simulations. We discuss applications of these techniques for quantum enhanced metrology.