Quantum memory for continuous-variable optical states

We are reporting on our progress towards universal quantum memory for light: a system that would allow storage and retrieval, with high fidelity, of an arbitrary optical state. Our apparatus employs parametric down-conversion for preparing quantum states of light, electromagnetically-induced transparency for their storage in atomic rubidium vapor and homodyne tomography for measuring the retrieved states. We demonstrate storage and retrieval of squeezed vacuum as a test of our system\'s capabilities.