Entangled ensembles have been created in versatile atomic systems and find a promising application in entanglement-enhanced metrology. Here, entangled spin-states have been successfully applied within interferometers ...

This thesis describes new results on the entanglement of atomic spins in Ramsey interferometry, optical atomic clocks and trapped ions. It is divided into three parts: First, we investigate improvements to conventional ...

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The predictions of quantum mechanics often differ from our everyday experiences. In the classical case, the state of a system can be predicted precisely, assuming the exact knowledge of all parameters. This is not possible ...