Speaker
Description
We report recent progress in precision spectroscopy of helium isotopes ($^{3,4}$He) and lithium ions ($^{6,7}$Li$^+$), focusing on extracting nuclear structure information from high-accuracy atomic transitions. For helium, we consider the off-diagonal hyperfine mixing effects to resolve the discrepancy in the squared charge-radius difference between $^3$He and $^4$He, leading to a new squared charge radius for helium that is more consistent with muonic atom spectroscopy measurements. For lithium, our high-precision calculations based on bound-state quantum electrodynamics have achieved uncertainties within tens of kHz. By combining these results with experimental measurements, we accurately extract nuclear structure parameters such as Zemach radii and electric quadrupole moments. The results show significant discrepancies between the extracted Zemach radius of $^6$Li and nuclear physics predictions, as well as between our determined nuclear electric quadrupole moment and the recommended value obtained from molecular spectroscopy. These nuclear structure insights provide critical benchmarks for understanding nuclear forces and testing nuclear theories, further advancing our understanding of bound-state quantum electrodynamics and nuclear structure theory. For instance, the discrepancies observed in the Zemach radius for $^6$Li have now been resolved through more comprehensive nuclear structure theory calculations.