2026/07/29 by Jaewhan Lee, Hyun Gyung Lee, Won-Kyu Lee +15
Physics and Astronomy · #physics.atom-ph
paper · pdf · doi:10.1088/1681-7575/ae8bb5
published as Jaewhan Lee et al 2026 Metrologia 63 045003 · 15 pages, 9 figures
crossref created 2026/07/16 · crossref issued 2026/07/29 · crossref published 2026/07/29 · crossref published-online 2026/07/29 · crossref deposited 2026/07/29 · crossref indexed 2026/07/29 · arxiv created 2026/07/31 · crossref published-print 2026/08/01 · arxiv updated 2026/08/03
We measure the absolute frequency of the 1S0 → 1P1 transition in strontium using two methods: fluorescence spectroscopy of a thermal atomic beam source from a compact low-power oven and velocity measurements of a slow atomic beam from a two-dimensional grating magneto-optical trap (2D gMOT). The measurements for both methods are performed in the same ultra-high vacuum chamber containing a diffraction grating chip which is placed below the strontium atoms that are being interrogated. The first method uses a probe laser beam incident on the grating chip such that the grating acts as an end mirror, with the first-order diffracted beam providing a retro-reflected probe beam. The counter-propagating laser beams traverse an atomic beam emitted from an oven, enabling spatially resolved fluorescence spectroscopy through CCD imaging and hyperfine-constrained multi-isotope fitting. The second method relies on a large profile cooling laser beam normally incident onto the grating chip which laser cools strontium atoms for a slow atomic beam source. The velocity of the atoms exiting the 2D gMOT is measured as a function of the laser detuning and intensity from which the resonance frequency can be estimated. The two methods are consistent within their quoted uncertainties. Using three datasets based on retro-beam spectroscopy measurements, and one dataset using slow atom beam velocity measurements, we determine the 1S0 → 1P1 transition frequency to be 650.503 815(5)~THz. Our result provides a re-evaluation of this 461 nm transition demonstrated on a compact laser cooling apparatus based on a diffraction grating platform.