Hot Topics Session

Over the last 20 years, science with ultracold atoms has focused on motion: slowing down motion, population of a single motional state (Bose-Einstein condensation, atom lasers), superfluid motion of bosons and fermion pairs.  In my talk, I will address the next challenge when motion is frozen out:  Spin ordering.  A two-component boson or fermion mixture can form magnetic phases such as ferromagnetic, antiferromagnetic ordering and a spin liquid.  The challenge is to reach the low temperature and entropy required to observe these phenomena.  I will describe our current efforts and progress towards this goal.  This includes Bragg scattering of atoms in a crystal of light (optical lattice), and a new adiabatic gradient demagnetization cooling scheme which has enabled us to realize spin
temperatures of less than 50 picokelvin in optical lattices.  These are the lowest temperatures ever measured in any physical system. We have also reached negative temperatures (which are, however, hotter than positive temperature). 

Preparation
For PhD students who have registered for the hot topics course it is necessary to prepare by reading documents / links mentioned below.