January 15 Colloquium
Christian Schneider, UCLA
Quantum Control of Atoms, Ions, and Nuclei
Cold atoms and ions provide an interesting playground for a variety of measurements of fundamental physics. Using RF traps, experiments become possible with both large ensembles of ions, e.g. in cold chemistry, and few/single ions, such as in quantum computations/simulations or optical clocks, where ultimate quantum control is required. In the first part of the talk, recent results from our work in cold chemistry and cold molecular ions using a hybrid atom-ion experiment will be presented. We have developed an integrated time-of-flight mass spectrometer, which allows for the analysis of the complete ion ensemble with isotopic resolution. Using this new setup, we have significantly enhanced previous studies of cold reactions in our system. Potential routes towards ultra-cold reactions at the quantum level will be presented. Current work aims at demonstrating rotational cooling of the molecular ions and photo-associating molecular ions.
The second part of the talk reports on our results of the search for the low-energy isomeric transition in thorium-229. This transition in the vacuum-ultraviolet regime (around 7.8 eV) has a lifetime of tens of minutes to several hours and is better isolated from the environment than electronic transitions. This makes it a very promising candidate for future precision experiments, such as a nuclear clock or tests of variation of fundamental constants, which could outperform implementations based on electronic transitions. Our approach of a direct search for the nuclear transition uses thorium-doped crystals and, in a first experiment, synchrotron radiation (ALS, LBNL) to drive this transition. We were able to exclude a large region of possible transition frequencies and lifetimes. Currently, we continue our efforts with enhanced sensitivity using a pulsed vuv laser system.