Sub-Doppler Cooling, State Preparation, and Optical Trapping of a Triel Atom
Ultracold gases of atoms from main group III (group 13) of the periodic table, also known as “triel elements,” have great potential for a new generation of quantum matter experiments. The first magnetooptical trap of a triel element (indium) was recently realized, but more progress is needed before a triel is ready for modern ultracold quantum science experiments in optical traps. Reaching this regime typically requires atoms that are cooled to the 10 μK level or below, prepared in pure quantum states, and confined in a laser field. Here we report the achievement of all three of these milestones in atomic indium. First, we perform polarization gradient cooling of an indium gas to 15 μK. Second, we spin polarize the gas into a single hyperfine sublevel of either the 5P1/2 indium ground state or the 5P3/2 metastable state. Third, we trap indium in a 1064 nm optical lattice, achieving a 3 s trap lifetime. With these results, indium is now a candidate for a next generation quantum research platform.
