Towards storage of non-classical light using electromagnetically induced transparency

Electromagnetically induced transparency (EIT) is a quantum interference effect in which a strong control laser beam changes a medium's linear dispersion and absorption allowing a weak signal beam to travel without absorption and with its group velocity greatly reduced. This allows the storage of quantum information on the irradiated atoms. We report on our recent progress in storing and retrieving a squeezed optical state using hyperfine ground levels of the D1 transition in rubidium-87. A narrowband source of nonclassical light for interaction with atoms has been constructed based on parametric amplification featuring a periodically poled KTP crystal. Ultrafast lossless switching allows us to generate 1 us pulses of up to 3 dB squeezed vacuum resonant to the EIT transparency window. We investigate the transmission and storage of these states under EIT conditions by homodyne tomography.