  An optical atomic clock scheme is developed that utilizes two lasers to
establish coherent coupling between the $5s^2 \phantom{}^1S_0$ ground state of
$^{88}$Sr and the first excited state, $5s5p \phantom{}^3P_0$. The coupling is
mediated by the broad $5s5p \phantom{}^1P_1$ state, exploiting the phenomenon
of electromagnetically induced transparency. The effective linewidth of the
clock transition can be chosen at will by adjusting the laser intensity. By
trapping the $^{88}$Sr atoms in an optical lattice, long interaction times with
the two lasers are ensured; Doppler and recoil effects are eliminated. Based on
a careful analysis of systematic errors, a clock accuracy of better than
$2\times 10^{-17}$ is expected.
