Highly efficient and long-lived optical quantum memory with cold atoms

Abstract

Quantum memory is an essential element for long distance quantum communi- cation and photonics quantum computation protocols. The practical implementation of such protocols requires an efficient quantum memory with long coherence time. Here, we report a highly efficient coherent optical memory via the gradient echo memory (GEM) technique in cold atoms. The efficiency is as high as 87% with the e-1 coherence time of 1 ms. The ability of quantum storage is verified using heterodyne tomography of small coherent states, showing that our system performs in the quantum regime Show more