Single-photon Level Quantum Memory in an Isotopically Pure 143Nd3+:Y7LiF4 Crystal

In an isotopically pure 143 Nd 3+ :Y 7 LiF 4 crystal we demonstrate an optical quantum memory on a single photon level using the atomic frequency comb memory protocol. Using weakened laser pulses we demonstrate storage efficiency of 6.5% with the storage time of ~ 60 ns and signal to noise ratio of around 3.