Abstract
Photonic quantum memory is a key component for long-distance quantum communication and optical quantum computation. High storage efficiency, long storage time, and high fidelity are the required features of a quantum memory. Coherent light storage based on the effect of electromagnetically induced transparency (EIT) has the potential and is promising for the application of quantum memory, owing to the quantum nature of light-matter interaction. Previously, the storage efficiency of EIT-based memory is however less than 50% (i.e. 1 failure per 2 operations), seemingly indicating that it is not compatible with quantum information technology. Recently, we experimentally demonstrated that as long as the optical density of a medium is sufficiently high and the decoherence rate of the system is enough low, the storage efficiency of EIT-based memory can approach unity. Our work brings EIT-based memory towards practical applications in quantum information processing with photons.