Erzeugung von robusten magnetfeldabhängigen Qubitzuständen für hochpräzise Magnetometrie

Traped ions can be used for quantum information processing (QIP) as elementary process units. For this purpose, the ability to manipulate the laser-cooled ions is essential. For many qubit operations, the ions have to be cooled to the ground state of their motion. The Raman sideband cooling method, which was used in this work, demonstrates that a single ion could be cooled to the fundamental vibrational state. Compared to laser light, microwave fields offer many advantages in stabilizing and scaling the system. In this thesis, a conducted Randomized Benchmarking test underlines the enormous potential of manipulating stored ions with microwave fields. It was shown that the error per processing step is less than 4 · 10 -4 . The very short coherence time T2 of the magnetic field dependent Qubits driven by microwave fields limit the implementation of this concept. Changes in the surrounding electro-magnetic fields lead to dephasing and limit the possible time for gate operations. In this thesis, a method is implemented that produces so-called Dressed States by the combination of internal atomic states with microwave fields, which are highly resistant to influences of the environment. For a Dressed States-Qubit the coherence time is extended by several orders of magnitude to a number of seconds compared to atomic magnetic field-dependent qubits. The coherence time of a sensor is the determining factor in quantum technology that limits the effective and precise measurement of magnetic fields. A new magnetometry protocol enables a Dressed States-Qubit an unprecedented magnetic field sensitivity of 4,6 pT/√Hz at 14 MHz located within the standard quantum limit. The method combines the high magnetic field sensitivity with a spatial resolution in the nanometer range. The advantage of this new approach compared to known conventional methods lies in the achievement of a very high sensitivity for spectral components of the magnetic field over a wide frequency range.