laser-cooling

For many years rubidium has been a workhorse in the investigation of ultracold atoms.  Now JQI scientists are using Rb to cool another species, ytterbium, an element prized for its possible use in advanced optical clocks and in studying basic quantum phenomena.   Yb shows itself useful in another way: it comes in numerous available isotopes, some of which are bosonic in nature and some fermionic.
Yb-171 has proven satisfactorily amenable to cooling in the atom trap lab of Steve Rolston and Trey Porto.  First Rb-87 atoms are loaded into a magneto-optic trap---an enclosure where magnetic fields and laser beams are used to confine atoms---and then cooled until they form a Bose-Einstein condensate (BEC).  Slow-moving Yb atoms, in contact with the Rb atoms, are cooled right along with them.  Thus Yb atoms lose excess energy to warming the colder Rb atoms.

Precise information about the magnetic properties of nuclei is critical for studies of what’s known as the ‘weak force.’ While people do not feel this force in the same way they feel electricity or gravity, its effects are universal. The weak force allows stuff to become unglued and form new elements through decay—the sun, for example, is powered through deuterium fuel, which is generated via weak force mediated interactions. The weak force is elusive as it operates between objects that are separated by miniscule distances deep within atomic nuclei. To study its properties physicists must be able to extract the weak interactions out of a jumbled sea of other, more dominant phenomena that, alongside the weak force, work to govern particle behavior. Physicists from the Francium Parity Non-Conservation (FrPNC) collaboration, which includes researchers from JQI Fellow Luis Orozco’s group, believe that the radioactive element francium is the perfect “laboratory” for uncovering the secrets of the weak force.To understand this force, physicists must carefully characterize many intricate aspects of francium. Recently, the team*, carried out precision measurements of the magnetic properties of the francium nucleus. They have succeeded in determining important, yet nearly imperceptible deviations from the point-like behavior in the francium (Fr) nucleus -- the so-called hyperfine anomaly. Their results were recently published in the journal Physical Review Letters. This research took place at TRIUMF in Vancouver BC, the Canadian national accelerator laboratory for nuclear and particle physics.