Microwave quantum memories using solid state spins

混合量子系统提供了令人兴奋的潜力，将不同类型的量子系统连接在一起，以利用各自的优势。超导量子比特非常适合执行量子逻辑门，但其相干时间通常为数十人，而硅中的供体电子自旋的相干时间为3秒，并且可以使用耦合核自旋存储和检索它们的状态，提供相干时间长达3小时。我们已经与CEA Saclay的合作者证明，硅中的自旋可以耦合到高Q因子超导腔中，从而产生珀塞尔增强的电子自旋弛豫，即电子自旋通过向腔中发射微波光子返回基态。这为单个自旋与微波光子的相干磁耦合以及使用超导谐振器作为量子总线连接超导量子比特和自旋存储器奠定了基础。这种量子存储器可以利用硅中的掺杂剂自旋，或者固体中的稀土缺陷。我们还展示了一种多模量子存储协议，其中多个微波量子比特状态可以在一个集成中独立存储和检索。该项目的目的是利用固体材料中的高相干自旋来存储微波光子态，作为量子信息技术的资源。这样的量子存储器将能够以高保真度存储和检索许多这样的状态，时间接近几秒钟，并与一个或多个超导量子比特接口。研究方法，包括将研究的工程和物理科学的新知识或新技术。项目方法包括超导谐振器设计、建模和纳米微制造，以及新型自旋系统和材料宿主的研究。电子自旋共振将用于研究自旋相干性和线宽特性，同时优化注入和退火工艺以提高自旋性能。稀释制冷机将用于实现高自旋极化，并确保超导量子比特的最佳操作。该项目与epsrc量子技术计划以及量子计算和模拟中心密切相关。该项目将受益于与Patrice Bertet CEA Saclay和Philippe Goldner Chemie ParisTech的持续学术合作。

Hybrid quantum systems offer the exciting potential to connect different types of quantum system together to exploit their respective strengths. Superconducting qubits are well suited for performing quantum logic gates but have coherence times typically in the tens of us, while electron spins of donors in silicon have coherence times to 3 seconds, and their states can be stored and retrieved using coupled nuclear spins, offering coherence times of up to 3 hours. We have shown with collaborators in CEA Saclay that spins in silicon can be coupled to high Q factor superconducting cavities to yield Purcell enhanced relaxation of electron spins i.e. electron spins return to the ground state by emitting a microwave photon into the cavity. This lays the foundation for coherent magnetic coupling of individual spins to microwave photons and for interfacing superconducting qubits and spin memories using a superconducting resonator as a quantum bus. Such quantum memories could make use of dopant spins in silicon, or rare earth defects in solids. We have also demonstrated a multimode quantum memory protocol where multiple microwave qubit states can be stored and retrieved independently in an ensemble. This aim of this project is to use highly coherent spins in solid state material to store microwave photon states, as a resource for quantum information technologies. Such a quantum memory would be able to store and retrieve many such states with high fidelity, over times approaching seconds, and interface with one or more superconducting qubits.The research methodology, including new knowledge or techniques in engineering and physical sciences that will be investigated. The project methodology includes superconducting resonator design, modelling and nano micro fabrication, along with the investigation of novel spin systems and material hosts. Electron spin resonance will be used to study the spin coherence and line width properties, while implantation and annealing processes will be optimised to improve spin performance. A dilution refrigerator will be used to achieve high spin polarisation and ensure optimal operation of the superconducting qubits.The project is strongly aligned with EPSRCs Quantum Technologies programme, as well as the Quantum Computing and Simulation Hub. The project will benefit from ongoing academic collaborations with the group of Patrice Bertet CEA Saclay and Philippe Goldner Chemie ParisTech.