Quantum atomic bath boosts Yb+ spectroscopy precision sixfold

Egor Kovlakov and Rene Gerritsma of the University of Amsterdam have achieved a six to ninefold increase in precision when measuring hyperfine interaction constants in ytterbium-173 (Yb+). The researchers performed laser spectroscopy on a trapped Yb+ ion, cooling it not with lasers, but with a surrounding “bath” of ultracold atoms via spin-exchange collisions. By probing the 6²S_(1/2) → 6²P_(3/2) transition at 329 nm, the team measured magnetic and electric hyperfine interaction constants of A = -241(1) MHz and B = 1460(8) MHz, surpassing the accuracy of previous hollow-cathode discharge experiments. Instead of relying on traditional laser cooling techniques, Egor Kovlakov and Rene Gerritsma coupled the trapped ¹⁷³Yb⁺ ion to a surrounding cloud of ultracold lithium-6 (⁶Li) atoms, a process that continuously cools the ion’s internal degrees of freedom via spin-exchange collisions. This innovative approach allowed for highly accurate spectroscopic analysis, surpassing the precision of previous measurements conducted using hollow-cathode discharge experiments. The team detected laser excitation of the ¹⁷³Yb⁺…