The advent of laser cooling some three decades ago produced trapped atomic gases at astoundingly low(sub-milli-Kelvin) temperatures, initiating the field of ultra-cold atomic physics. This field, recognized by two separate Nobel Prizes, has remained at the cutting-edge of physics research because these degenerate gases are pristine systems for exploring fundamental quantum phenomena.
A key factor in the progress made with these systems is the detailed understanding of atomic interactions and how they can be controlled. For example, using so-called Feshbach resonances, the interactions between atoms can be varied from being attractive to repulsive by adjusting the strength of an external magnetic field. This provides a unique control parameter to explore paradigmatic condensed matter physics such as superconductivity in strongly interacting gases. However, it is not possible to directly calculate atomic interaction potentials from first principles, and current understanding is provided by theoretical models that have been determined (and continue to be optimized) by comparison to experimental measurements.
Laser Based Collider for Ultracold atoms
in a regime of extreme contrast: it will use samples of atoms at nano-Kelvin temperatures accelerated to pedestrian velocities of up to a meter per second. The full execution of this collider utilizes collaborations with theorists who have developed state-of-the-art calculations to extract key information from the experimental scattering patterns.
This collider extends our previous magnetic collider experiments.
Click above to download high res image of our steerable tweezer system
BECs in configurable time-averaged double-wells
Winding spin waves in a gas of ultracold Rubidium atoms
Dispersive probing of Rabi oscillations on between the stretched hyperfine states of Rb87
New optical layout for dual species MOT
Homebuilt motorized rotation mounts for wave plates
Click here to see animation
Dispersive Interrogation of an ultracold atomic cloud during rf evaporation (October 2012)
We have used nondestructive laser probing to follow the central density evolution of a trapped atomic cloud during forced evaporative cooling. This was achieved in a heterodyne dispersive detection scheme. We propose to use this as a precursor measurement for predicting the atom number subsequent to evaporation and provide a simple experimental demonstration of the principle leading to a conditional reduction of classical number fluctuations.
780 nm diode laser.
This laser is intended to form the back bone in a new architecture for
cooling, repumper, pumper, and probe light in our experiment.
Click to watch
One of the first images of rubidium-87 atoms undergoing s-wave scattering in the new optical collider.
One of the early shots of a Rubidium-87 BEC in the |2,2> state. Subsequently, we managed to make bigger, more pure BECs:
The cloud all the way on the left is a purely thermal cloud. A BEC emerges in the next cloud on the right. As we cool further, the thermal atoms disappear and we are left with an almost pure BEC.