Ultra-cold collisions of metastable alkaline-earth atoms

Kiyoshi Ueda

Paul S. Julienne, J. Vigué

Dirk P. Hansen, Andreas Hemmerich

Recent theoretical work indicates that collisions between metastable alkaline-earth atoms (AEAs) in the presence of external magnetic fields should be largely determined by partial waves with large angular momenta even at very low temperatures. Unusually large inelastic collision cross sections were predicted and doubts have been raised regarding the feasibility of evaporative cooling of metastable AEAs in magnetic traps. Here we present experimental data for 40Ca[4s4p]3 P2 clearly confirming the asserted multichannel character of the collision mechanism. While elastic cross sections are found to be similar to the predicted values, inelastic cross sections exceed the calculations by an order of magnitude. Our results substantiate the expectation of inefficient evaporative cooling.

G.R. Woestenenk, Hennie C. Mastwijk, Jan W. Thomsen +4 more

Pavao Santak

Physicists have been trying to create artificial magnetic systems using ultra-cold atomic gases as their simulators. However, behavior of many ultra-cold atomic systems is not very well understood yet. Ultra-cold fermionic alkaline earth atomic (AEA) gases are one of those systems. In this thesis, we study the effects of thermal fluctuations on the overall macroscopic behavior of ultra-cold fermionic AEA gases using a particular semiclassical model. We study the AEA systems on a square lattice with periodic boundary conditions. To investigate the behavior of AEA systems under the effects of thermal fluctuations, we analyze several different types of correlation functions, which correspond to different physical observables. We analyze the correlation functions using the results obtained from Monte Carlo simulations. We show that for the cases studied, all the correlation functions approach zero as the system size goes to infinity at any temperature, indicating that no phase transition occurs as a consequence of thermal fluctuations.

Jan W. Thomsen, Philip G. Westergaard, Rastin Matin +2 more

Techniques of modern quantum optics allows for the preparation of ultra-cold atoms in well controlled quantum states ideal for precision measurements and tests of fundamental laws of physics. We report on our recent progress with precision measurements using alkaline earth atoms.