2024/11/15 by Jin-Lu Wen, Jiadong Tang, Wen, Jin-Lu +11
Physics and Astronomy · #Atomic Physics (physics.atom-ph) #Atomic and Subatomic Physics Research #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences #Quantum Physics (quant-ph) #Quantum, superfluid, helium dynamics
paper · pdf · doi:10.48550/arxiv.2411.09958
openalex publication_date 2024/11/15 · openalex created_date 2024/11/21 · openalex updated_date 2026/07/28
Post-selecting output states in measurements can effectively amplify weak signals and improve precision. However, post-selection effects may also introduce unintended biases in precision measurements. Here, we investigate the influence of post-selection in the precision spectroscopy of the 23S - 23P transition of helium (4He) using an atomic beam. We directly observe that post-selection based on atomic positions causes a shift in the measured transition frequency, amounting to approximately -55 kHz. After accounting for this post-selection shift, we obtain a corrected frequency of 276,764,094,712.45 ± 0.86 kHz for the 23S1 - 23P0 transition. Combining this result with existing data for 3He, we derive a new value for the difference in squared nuclear charge radii, δr2 [rh2 - rα2] = 1.0733 ± 0.0021 fm2. This value shows a 2.8σ deviation from measurements of muonic helium ions, potentially pointing to new physics that challenges lepton universality in quantum electrodynamics.