Storage of telecom-C-band heralded single photons with orbital-angular-momentum encoding in a crystal

Room temperature atomic frequency comb storage for light

We demonstrate coherent storage and retrieval of pulsed light using the atomic frequency comb protocol in a room temperature alkali vapor. We utilize velocity-selective optical pumping to prepare multiple velocity classes in the F=4 hyperfine ground state of cesium. The frequency spacing of the classes is chosen to coincide with the F^'=4-F^'=5 hyperfine splitting of the 6²P_3/2 excited state, resulting in a broadband periodic absorbing structure consisting of two usually Doppler-broadened optical transitions. Weak coherent states of duration 2ns are mapped into this atomic frequency comb with pre-programmed recall times of 8ns and 12ns, with multi-temporal mode storage and recall demonstrated. Utilizing two transitions in the comb leads to an additional interference effect upon rephasing that enhances the recall efficiency.

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 (∼5GHz), thereby significantly exceeding the hyperfine ground and excited state splitting (∼10MHz). 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.

A noise-resisted scheme of dynamical decoupling pulses for quantum memories

Stable quantum memories that capable of storing quantum information for long time scales are an essential building block for an array of potential applications. The long memory time are usually achieved via dynamical decoupling technique involving decoupling of the memory states from its local environment. However, because this process is strongly limited by the errors in the pulses, an noise-protected scheme remains challenging in the field of quantum memories. Here we propose a scheme to design a noise-resisted [Formula: see text] pulse, which features high fidelity exceeding [Formula: see text] under realistic situations. Using this [Formula: see text] pulse we can generate different dynamical decoupling sequences that preserve high fidelity for long time scales. The versatility, robustness, and potential scalability of this method may allow for various applications in quantum memories technology.