Higher-Order QED Corrections to the Hyperfine Splitting in ³He

We present a calculation of the hyperfine splitting of the 2(3)S state in the He-3 atom with inclusion of all QED effects up to alpha E-3(F), where E-F is the Fermi splitting. Using the experimental value of the 1S hyperfine splitting in He-3(+), we eliminate uncertainties from the nuclear structure and obtain the theoretical prediction for 3He of v(hfs) = -6 739 701 181(41) Hz, which is in perfect agreement with the experimental value - 6 739 701 177(16) Hz [S. D. Rosner and F. M. Pipkin, Phys. Rev. A 1, 571 (1970)]. This result constitutes a 40-fold improvement in precision as compared to the previous value and is the most accurate theoretical prediction ever obtained for a nonhydrogenic system.