Noise Free On-Demand Atomic Frequency Comb Quantum Memory

We present an extension of the atomic frequency comb protocol that utilizes the Stark effect to perform noise-free, on-demand, control. An experimental realization of this protocol was implemented in the Pr${}^{3+}$:Y${}_2$SiO${}_5$ solid-state system, and a recall efficiency of 38% for a 0.8 $\mu$s storage time was achieved. Experiments were performed with both bright pulses as well as weak-coherent states, the latter achieving a signal-to-noise ratio of $570 \pm 120$usinginputpulseswithanaveragephotonnumberof$\sim 0.1$. The principal limitation for a longer storage time was found to be the minimum peak width attainable for Pr${}^{3+}$:Y${}_2$SiO${}_5$. We employ an adaptation of an established atomic-frequency comb model to investigate an on-demand, wide-bandwidth, memory based on Eu${}^{3+}$:Y${}_2$SiO${}_5$. From this we determine that a storage time as long as 100 $\mu$s may be practical even without recourse to spin-wave storage.