Photon-echo quantum memories in inhomogeneously broadened two-level atoms

Here, we propose a solid-state quantum memory that does not require spectral holeburning, instead using strong rephasing pulses like traditional photon-echo techniques. The memory uses external broadening fields to reduce the optical depth and so switch off the collective atom-light interaction when desired. The proposed memory should allow operation with reasonable efficiency in a much broader range of material systems, for instance Er³⁺ doped crystals which have a transition at 1.5 μm. We present analytic theory supported by numerical calculations and initial experiments.