We experimentally investigate the transient dynamics of an optical cavity field interacting with large ion Coulomb crystals in a situation of electromagnetically induced transparency (EIT). EIT is achieved by injecting a probe field at the single photon level and a more intense control field with opposite circular polarization into the same mode of an optical cavity to couple Zeeman substates of a metastable level in 40Ca+ ions. The EIT interaction dynamics are investigated both in the frequency-domain – by measuring the probe field steady state reflectivity spectrum – and in the time-domain – by measuring the progressive buildup of transparency. The experimental results are observed to be in excellent agreement with theoretical predictions taking into account the inhomogeneity of the control field in the interaction volume, and confirm the high degree of control on light-matter interaction that can be achieved with ion Coulomb crystals in optical cavities.
We demonstrated coupling of rare-earth-metal ions in a crystal to a macroscopic cavity mode by observing optical bistability and normal-mode peaks due to sweeping-laser-induced population redistribution of the ions. The experimentally evaluated coupling constant between the individual ions and the single cavity mode is
15kHz, which is comparable with or larger than the dissipation of the ions and will exceed the cavity dissipation with a narrowing of the mode waist of the cavity to the wavelength. The results advance the application of a coupled system of rare-earth-metal ions in a crystal and an optical cavity for quantum information processing.