Sub-Doppler cooling, state preparation, and optical trapping of a triel atom

TL;DR

This paper demonstrates the cooling, state preparation, and optical trapping of indium atoms, advancing ultracold triel atom research for quantum science applications.

Contribution

It reports the first combined achievement of sub-Doppler cooling, hyperfine state polarization, and optical trapping of indium atoms.

Findings

Achieved 15 μK polarization gradient cooling of indium.

Successfully spin polarized indium into a single hyperfine state.

Trapped indium atoms in an optical lattice with a 3-second lifetime.

Abstract

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 magneto-optical 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 uK 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 uK. Second, we spin polarize the gas into a single hyperfine sublevel of either the $5P_{1/2}$ indium ground state or the $5P_{3/2}$ 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.