Abstract
Statistical inference of a parameter based on measurements from an ensemble of uncorrelated particles is lower bounded by the classical precision limit or the standard quantum limit (SQL). Quantum entangled ensembles can beat the SQL. Several paradigms for such enhanced interferometries will be discussed, and experimental demonstrations with spinor atomic Bose-Einstein condensates reported. Many-atom squeezed states, entangled states with reduced quantum noise, are deterministically generated and applied in linear interferometry [1,2,3]; effective time-reversed evolutions of entanglement generating interactions are implemented in nonlinear interferometry to amplify signal preferentially over noise [4,5,6], both observing quantum enhanced precisions.
