Quantum metrology with Bose Einstein Condensates (Prof. M. Oberthaler)

Quantum metrology is about the exploration of these new limits by the generation and characterization of useful quantum mechanical resources. Since the gain in precision is intimately connected to quantum entanglement in many particle systems these investigations are also interesting from a fundamental point of view. In the colloquium I will discuss in detail how Bose Einstein condensates can be used to generate entangled many particle states which push atom interferometry beyond the classical limits. 

I will use the system of two component atomic condensates as a model system for explaining how quantum correlations arise and how they can be used for improved estimation of a phase shift in an atom interferometer. The simplest form of useful many particle quantum states are spin squeezed states which can be classified as Gaussian states. I will also discuss that the experimental platform of Bose Einstein condensates make it possible to generate deterministically two-mode squeezed vacuum and non-gaussian states. The demonstration of entanglement present in these states have been shown by extracting bounds on the quantum Fisher information as well as precise time-reversal of many particle quantum dynamics.