Lifetime Determination of the 5s5p ^3P^o_0 Metastable State in ^87Sr from the Electric Dipole Matrix Element

We report a measurement of the radiative lifetime of the 5s5p ^3P^o_0 metastable state in ^87Sr, which is coupled to the 5s^2 ^1S_0 ground state via a hyperfine-induced electric dipole transition. The radiative lifetime is determined to be 151.4(48) s, in good agreement with theoretical results. Our approach relies on accurate measurements of laser intensity and free-space Rabi frequency, enabling lifetime measurements of any excited state and particularly suitable for long-lived states.