Storage of photons for quantum networking

Quantum communication involves distributing quantum resources—primarily photons—with applications in quantum computing, sensing, and secure information exchange. The ultimate goal is to develop a quantum internet, analogous to today's classical internet, capable of efficiently transmitting photonic qubits over long distances. However, photon loss in optical fibers increases exponentially with distance, posing a key challenge for long-range quantum communication. Quantum repeaters mitigate this by dividing long links into shorter elementary segments, where entanglement is generated, stored, and swapped to establish end-to-end connections. Quantum Memories (QMs) are essential for synchronizing operations across segments, reducing the time scaling from exponential to polynomial with distance. In this work, we present the demonstration of a practical solid-state quantum memory using erbium (Er) ions, which operate at telecom wavelengths compatible with existing fiber-optic infrastructure. We achieve on-demand storage and retrieval of single photons with state-of-the-art storage time and efficiency. Crucially, our memory operates without involving spin-level transitions, simplifying the system design and improving its robustness. This eliminates the need for addressing an additional spin-level, thus marking an important advancement in the path toward scalable, real-world quantum repeaters. Our results demonstrate a significant step toward realizing a functional and deployable quantum internet infrastructure.