Combined quantum transducer and memory on a hybrid solid-state platform

基于超导微波电路的量子比特已经成为量子处理器的主导平台。然而，它们缺乏对未来量子计算机的高级应用至关重要的关键特性。例如，它们相对较短的相干时间阻止了量子比特的长时间存储，并且它们在微波条件下的操作使得它们不可能在10MK低温环境之外的任何距离上传输它们的量子比特。一种自然的方法是实现一个混合平台，在该平台上超导量子比特由另一个平台补充，该平台确实允许长期存储微波量子比特并将其转换/转换为光学波长量子比特。我们提出了一种稀土离子掺杂的固态平台来同时实现这两个特性。更准确地说，掺Yb：YSO(Yb：YSO)具有独特的特性，保证了存储的长相干时间和与微波量子位兼容的频率的自旋跃迁。至关重要的是，这些性质存在于与超导量子比特兼容的条件下，例如零磁场。我们的项目旨在开发和成熟这种超导量子比特和新型Yb基固体材料的混合平台。该项目将展示Yb：YSO晶体中光学和微波光子的量子存储，并探索量子波长转换的要求以及原理验证实验。另一个目标是将我们的平台与基于波长匹配Yb光学跃迁的量子点发射器的量子光源集成在一起。这些步骤将导致一种完全集成的光电子学设备，用于在未来的量子互联网上连接量子计算机，从而为量子计算行业的最终用户以及未来的量子网络运营商提供市场机会。我们解决了开发使用多量子比特和纠缠来实现信息相互转换、增强量子处理能力和量子通信以实现基于物理的信息安全的量子器件和应用所面临的挑战。

Quantum bits (Qubits) based on superconducting microwave circuit have emerged as the leading platform for quantum processors. However, they lack key properties that are essential for future advanced applications of quantum computers. For example, their relatively short coherence time prevents long time storage of the qubits and their operation in the microwave regime makes it impossible to transmit their qubits over any distance outside their 10 mK cryogenic environment. A natural approach is to implement a hybrid platform on which the superconducting qubits are complemented by another platform, which does allow long term storage of microwave qubits and the conversion/transduction into optical wavelength qubits. We propose a rare-earth-ion doped solid-state platform to simultaneously enable both features. More precisely, ytterbium-doped yttrium-orthosilicate (Yb:YSO) has unique features, which guarantee long coherence times for storage and spin-transitions at frequencies compatible with microwave qubits for transduction. Crucially, these properties exist under conditions, such as zero magnetic field, compatible with the superconducting qubits. Our project aims to develop and mature this hybridized platform of superconducting qubits and the novel Yb based solid-state material. The project will demonstrate quantum memory for both optical and microwave photons in an Yb:YSO crystal and explore the requirements for quantum wavelength transduction along with proof-of-principle experiments. A further goal is to integrate our platform with quantum light sources based on quantum-dot emitters with wavelength matching the Yb optical transition. These steps would lead to a fully integrated photonics device for interfacing quantum computers over a future quantum Internet, and, thus, present a market opportunity with end-users in the quantum computing industry as well as future quantum network operators. We address the challenges of developing quantum devices and applications that use multiple qubits and entanglement to realize interconversion of information, enhancement of quantum processing capabilities and quantum communication for physics-based information security.