Quantum logic spectroscopy of trapped ions

Abstract:
Precision spectroscopy is a driving force for the development of our physical understanding. However, only few atomic and molecular systems of interest have been accessible for precision spectroscopy in the past, since they miss a suitable transition for laser cooling and internal state detection. This restriction can be overcome in trapped ions through quantum logic spectroscopy. Coherent laser manipulation originally developed in the context of quantum information processing with trapped ions allows us to combine the special spectroscopic properties of one ion species (spectroscopy ion) with the excellent control over another species (logic or cooling ion). The logic ion provides sympathetic cooling and is used to control and read out the internal state of the spectroscopy ion. In my presentation I will provide an overview of different implementations of quantum logic spectroscopy suitable for narrow (long-lived) and broad (dipole-allowed) transitions. Applications range from highly accurate optical clocks based on aluminium ions, over precision spectroscopy of broad and non-closed transitions in calcium isotopes, to non-destructive internal state detection and spectroscopy of molecular ions. Prospects to extend quantum logic spectroscopy to highly charged ions and first steps towards this goal will be discussed. Highly charged ions are among the most sensitive systems to probe for a variation of the fine-structure constant and hold the promise for high accuracy optical clocks.