Quantum memory of a squeezed vacuum for arbitrary frequency sidebands

Abstract

We have developed a quantum memory that is completely compatible with current quantum information processing for continuous variables of light, where arbitrary frequency sidebands of a squeezed vacuum can be stored and retrieved using bichromatic electromagnetic induced transparency. The 2 MHz sidebands of squeezed vacuum pulses with temporal widths of 470 ns and a squeezing level of $\ensuremath{-}1.78\ifmmode\pm\else\textpm\fi{}0.02$ dB were stored for 3 $\ensuremath{\mu}$s in laser-cooled $^{87}\mathrm{Rb}$ atoms. Squeezing of $\ensuremath{-}0.44\ifmmode\pm\else\textpm\fi{}0.02$ dB, which is the highest squeezing reported for a retrieved pulse, was achieved.