Sympathetic EIT laser cooling of motional modes in an ion chain

We use electromagnetically induced transparency (EIT) laser cooling to cool motional modes of a linear ion chain. As a demonstration, we apply EIT cooling on ${}^{24}M{g}^{+}$ ions to cool the axial modes of a ${}^{9}B{e}^{+}$ - ${}^{24}M{g}^{+}$ ion pair and a ${}^{9}B{e}^{+}$ - ${}^{24}M{g}^{+}$ - ${}^{24}M{g}^{+}$ - ${}^{9}B{e}^{+}$ ion chain, thereby sympathetically cooling the ${}^9$Be${}^{+}$ ions. Compared to previous implementations of conventional Raman sideband cooling, we achieve approximately an order-of-magnitude reduction in the duration required to cool the modes to near the ground state and significant reduction in required laser intensity.