2025/08/06 by Naohiro Okamoto, T. Aoki, Okamoto, Naohiro +3 · 2 citations
Physics and Astronomy · #Advanced Frequency and Time Standards #Atomic Physics (physics.atom-ph) #Atomic and Subatomic Physics Research #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences
paper · pdf · doi:10.48550/arxiv.2508.04109
openalex publication_date 2025/08/06 · openalex created_date 2025/10/16 · openalex updated_date 2026/07/30
We explore the efficacy of optical pumping on the 5s4d 1D2 - 5s8p 1P1 (448 nm) transition in a magneto-optical trap (MOT) of Sr atoms. The number of trapped atoms is enhanced by a factor of 12.0(6) relative to the case without repumping light, which is six times as large as that obtained using the pumping transition 5s4d 1D2 - 5s6p 1P1 (717 nm). This enhancement is limited by decay pathways that bypass the 5s4d 1D2 state, namely 5s5p 1P1 → 5s4d 3D1 → 5s5p 3P0 and 5s5p 1P1 → 5s4d 3D2 → 5s5p 3P2, which account for 8% of the total loss of the trapped atoms. We determine the decay rates for the 5s5p 1P1 → 5s4d 3D1 and 5s5p 1P1 → 5s4d 3D2 transitions to be 66(6) \mathrms-1 and 2.4(2)×102 \mathrms-1, respectively. Furthermore, we experimentally demonstrate for the first time that, when the trap beam diameter is small, escape of atoms in the 5s4d 1D2 state, which has a relatively long lifetime of 400 μs, becomes a dominant loss mechanism, and that the 448 nm pumping light effectively suppresses this escape. Our findings will contribute to improved laser cooling and fluorescence imaging in cold strontium atom platforms, such as quantum computers based on optical tweezer arrays.