SPECIAL TIME AND LOCATION - Quantum control of atoms, ions, and nuclei

Date: 
Friday, January 16, 2015 -
10:00am to 12:00pm
Speaker: 
Christian Schneider
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 on 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
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.