I will discuss three examples of connecting optical and micro wave photons to spins as quantum memory and compare their advantages and disadvantages for implementations in quantum information devices.
The T centre, a silicon-native spin-photon interface with telecommunications-band optical transitions and long-lived microwave qubits, offers an appealing new platform for both optical quantum memory and microwave to optical telecommunications band transduction. A wide range of quantum memory and transduction schemes could be implemented on such a platform, with advantages and disadvantages that depend sensitively on the ensemble properties. In this work we characterize T centre spin ensembles to inform device design. We perform the first T ensemble optical depth measurement and calculate the improvement in centre density or resonant optical enhancement required for efficient optical quantum memory. We further demonstrate a coherent microwave interface by coherent population trapping (CPT) and Autler-Townes splitting (ATS). We then determine the most promising microwave and optical quantum memory protocol for such ensembles. By estimating the memory efficiency both in free-space and in the presence of a cavity, we show that efficient optical memory is possible with forecast densities. Finally, we formulate a transduction proposal and discuss the achievable efficiency and fidelity.
The T center, a silicon-native spin-photon interface with telecommunication-band optical transitions and long-lived microwave qubits, offers an appealing new platform for both optical quantum memory and microwave-to-optical telecommunication-band transduction.A wide range of quantum memory and transduction schemes could be implemented withT center ensembles with sufficient optical depth, with advantages and disadvantages that depend sensitively on the ensemble properties.In this work we characterize T center spin ensembles to inform device design.We perform the first T ensemble optical depth measurement and calculate the improvement in center density or resonant optical enhancement required for efficient optical quantum memory.We further demonstrate a coherent microwave interface by coherent population trapping and Autler-Townes splitting.We then determine the most promising microwave and optical quantum memory protocol for such ensembles.By estimating the memory efficiency both in free space and in the presence of a cavity, we show that efficient optical memory is possible with reasonable optical density forecasts.Finally, we formulate a transduction proposal and discuss the achievable efficiency and fidelity.
Abstract An optical quantum memory is a device that can store photonic quantum information and release it after a controlled time. It is an essential component for overcoming channel losses in large‐scale quantum networks. Optical quantum memories have been demonstrated with various physical systems including atomic gases, single atoms in optical cavities, and rare‐earth‐ion doped solids. Now, quantum memories are marching toward miniaturization and integration for large‐scale practical applications. Solid state systems stand as a natural choice due to the physical stability and ease of micro or nano fabrication using well‐established techniques. In the past decade, considerable efforts have been devoted to developing photonic integrated quantum memories, that is, quantum memories based on micro/nano‐photonic structures manufactured in solids. Remarkable performances have been achieved with integrated quantum memories, with the advantages of lower laser/electric power requirements, small volumes, large storage densities, and easy implementations. In this article, the basic concepts of optical quantum memories, the state‐of‐the‐art technologies for fabricating integrated quantum memories in rare‐earth ions doped crystals, and recent advances are introduced, and the roadmap for developing practically useful devices for applications in quantum networks is discussed.