Writing and reading quantum states of light with tunable cavity: Application to single-photon sources

A method of writing and reading single-photon states of light in quantum memory devices whose information carriers are optically thin resonant media placed in a cavity is developed. It is shown that, using a tunable cavity, it is possible to write and reproduce Gaussian single-photon wave packets with an efficiency close to unity. The possibility of using this method for the transformation of the time shape of single photons generated in the cavity-enhanced spontaneous parametric down conversion regime is analyzed.