FERDINAND SCHMIDT-KALER - Modern Quantum Technology with trapped Ions

Ferdinand Schmidt-Kaler

QUANTUM, Institute of Physics, University of Mainz.

Jueves 23/10/2014, 14 hs.

Aula Seminario, 2do piso, Pabellón I.

The quantum states of ions are perfectly controlled, and may be used for fundamental research in quantum physics, as highlighted by the Nobel Prize given to Dave Wineland in 2012. Two directions of quantum technologies, followed by the Mainz group, have high impact on solid state physics:

I) The delivery of single cold ions on demand for the deterministic doping of solid state materials with nm spatial precision to generate design-structures optimized for quantum processors: Using single ejected Ca+ ions we reach 8nm wide spot, which can be used for imaging. Co-trapped N2+ ions have been ejected, this will lead to the fabrication of arrays of NV center in diamond, well suited for solid state quantum processors.

II) Phase transitions, universal laws of defect formation and non-linear interactions with trapped ions: Control parameters may be tailored such that a structural phase transition from a linear to a zigzag configuration of the crystal is crossed. Trapped ions serve here as a clean model system to investigate universal laws of defect formation when such transition is crossed fast and causally separated regions form. The amount of defects is predicted by the Kibble-Zurek mechanism. We have experimentally determined the universal scaling exponent for defect formation and confirm the scaling law for the inhomogeneous Kibble-Zurek effect accurately at the percent level. Next steps are studies of the Peierls Nabarro potential which keeps defects trapped in the crystal. Approaching the phase transition at the critical point is leading to large non-linear interactions of in the ion crystal normal modes. I will show how the application of multi-dimensional spectroscopy allows to determine effects such as cross-Kerr coupling or resonant coupling between vibrational modes, non-linear effects well known in non-linear optics.