Integrated Optical Memory Based on Laser-Written Waveguides

Quantum memory is an essential building block for applications in quantum information science, where scalability and integrability are needed for progress toward large-scale architectures. The authors present a platform for integrated photonic memory, based on laser-written waveguides in rare-earth-doped crystals. The coherence properties of the optically active ions persist after micromachining, enabling proof-of-principle light storage using the full atomic-frequency-comb protocol. This is a pioneering demonstration of on-demand optical memory on a chip.