We have a new paper out in the Journal of the Optical Society of America B, about how we process our images to remove interference fringes. Extending the traditional principle component analysis (PCA) method by using a Fourier-filtering method, we achieve better fringe reduction compared to simple PCA. Read about it here: https://doi.org/10.1364/JOSAB.391297.
Shown above is a 1D-cut of the density profile (false color image in the inset) of our cold lithium molecules after time-of-flight expansion. The gray fraction shows the thermal expectation, the red line coming above that value indicates the presence of a Bose-Einstein condensate of the molecules. Our little twist on this experiment is to use a mixture where no atom is in the hyperfine ground state (the first and second hyperfine states are used). This mixture is paving the way for another set of experiments we are working on currently… anyhow check it out!
Congratulations to Dr. Yun Long and the lithium team as they are now evaporating ultracold lithium-6 atoms into molecular Bose-Einstein condensates. This unique cold-atom phase starts with our magneto-optical trap (MOT) after which we do gray molasses cooling on the lithium-D1 line. Then, the atoms are loaded into a high power laser beam (similar to so-called optical tweezers), of which the intensity is gradually reduced. As the trap becomes weaker, the hot atoms escape, leaving a lower temperature gas behind. This evaporative cooling process continues until the atoms stick together in molecular pairs similar to nitrogen or oxygen molecules in air (note however, that our molecules are not in the ground state, but are instead quite weakly bound). Finally, when the temperature is low enough, these molecular pairs for the Bose-Einstein condensate, seen above as a sharp increase in the density of atoms with near-zero momentum. The images show (approximately) the momentum distribution of the molecules. The above images contain about 200,000 molecules at various temperatures near 500 nanoKelvin. Using these condensates, we have an exciting array of experiments planned to test correspondence between these cold atoms and electrons in materials with unusual properties. Stay tuned!
Our group has been awarded the prestigious Young Investigator Program grant from the Air Force Office of Scientific Research. The $450,000 award will be used over three years to investigate the Kondo effect in ultracold gases. Read the press release here (link).
The Parker Lab has now made our first lithium Magneto-Optical Trap. Using six-beams of laser light, we cool lithium-6 atoms to near 1 mK (1/1000 of a degree from absolute zero!). This exciting development is the first step toward realizing our quantum simulations! Congratulations to the team!