Condensed phase atomic sample for quantum information investigation

The paper reports on the development of optical coherent transient techniques to efficiently build a single frequency sample. These techniques are tested in a Tm³⁺:YAG crystal cooled at 4 K or immersed in superfluid helium. All experiments are concentrating on optically driven population transfer from ground state ³H₆ to upper state ³H₄ and back. This two-level system is complemented by level ³F₄, a metastable shelving state connected to the upper level by a nonradiative transition.