Gigahertz-bandwidth optical memory in Pr3+:Y2SiO5

We experimentally study a broadband implementation of the atomic frequency comb (AFC) rephasing protocol with a cryogenically cooled Pr3+ : Y2SiO5 crystal. To allow for storage of broadband pulses, we explore a novel, to the best of our knowledge, regime where the input photonic bandwidth closely matches the inhomogeneous broadening of the material (similar to 5 GHz), thereby significantly exceeding the hyperfine ground and excited state splitting (similar to 10 MHz). Through an investigation of different AFC preparation parameters, we measure a maximum efficiency of 10% after a rephasing time of 12.5 ns. With a suboptimal AFC, we witness up to 12 rephased temporal modes. (C) 2021 Optical Society of America

Automated summary

In this experiment, a cryogenically cooled Pr3+ : Y2SiO5 crystal was used to implement a broadband rephasing protocol for the atomic frequency comb (AFC). The study investigated the efficiency of AFC preparation parameters and observed up to 12 rephased temporal modes with a suboptimal AFC.