Future quantum photonic networks require coherent optical memories for synchronizing quantum sources and gates of probabilistic nature. We demonstrate a fast ladder memory (FLAME) mapping the optical field onto the superposition between electronic orbitals of rubidium vapor. Employing a ladder level-system of orbital transitions with nearly degenerate frequencies simultaneously enables high bandwidth, low noise, and long memory lifetime. We store and retrieve 1.7-ns-long pulses, containing 0.5 photons on average, and observe short-time external efficiency of 25%, memory lifetime (1/e) of 86 ns, and below 10−4 added noise photons. Consequently, coupling this memory to a probabilistic source would enhance the on-demand photon generation probability by a factor of 12, the highest number yet reported for a noise-free, room-temperature memory. This paves the way towards the controlled production of large quantum states of light from probabilistic photon sources.
@article{arxiv.1708.01919,
title = {Fast, noise-free memory for photon synchronization at room temperature},
author = {Ran Finkelstein and Eilon Poem and Ohad Michel and Ohr Lahad and Ofer Firstenberg},
journal= {arXiv preprint arXiv:1708.01919},
year = {2018}
}