Molecular switches and qubits
One topic of our research is switchable molecules whose state can be reversibly switched by light or other external stimuli. In addition to applications in highly sensitive nanoscale sensor technology, some magnetic molecules are particularly interesting candidates as qubits. We are working on characterising their properties and switching process using synchrotron and FEL-based methods.
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"A watched pot never boils" – this old English proverb refers to our subjective perception of time, but it also describes a problem with modern quantum technologies: the influence of an observer - or a classical measurement/interaction with the environment. This influence causes the special quantum properties to be lost within the so-called decoherence time, i.e. the quantum behaves like a classical particle. Thus, in quantum computing, interaction with the environment must be minimised so that the decoherence time is as long as possible.
Numerous different approaches are currently being pursued to realise the hardware of a quantum computer; we are focusing on metal ion complexes with lanthanide ions. In these complexes, the relevant magnetic 4f states are shielded by delocalised (5s,5p) states from the environment as if by a Faraday cage. In theory, the interaction with the atomic nucleus can be eliminated by crystal field engineering.
Verifying the theoretical prediction is the subject of our research in cooperation with chemists from Forschungszentrum Jülich and RWTH Aachen University. A particular focus is on investigating the influence of modifications to the crystal field (changes in symmetry and/or bond lengths) on electronic structure and magnetic properties.
Selected publications
H. Kaur, Characterisation of Molecular Magnets for Quantum Computing, Masterarbeit, Betreuung: C. Schmitz-Antoniak, FU Berlin, 2022