Microwave quantum memories using solid state spins

混合量子系统提供了将不同类型的量子系统连接在一起以发挥各自优势的令人兴奋的潜力。超导量子比特非常适合执行量子逻辑门，但相干时间通常在几十我们之间，而硅中施主的电子自旋的相干时间为3秒，它们的状态可以使用耦合的核自旋来存储和检索，提供长达3小时的相干时间。我们与CEA Saclay的合作者已经证明，硅中的自旋可以耦合到高Q因子的超导腔中，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内发射微波光子而返回基态。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母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态可以在一个系综中独立地存储和检索。这个项目的目的是利用固态材料中的高度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的速度存储和检索许多这样的状态，时间接近几秒，并与一个或多个超导量子比特连接。研究方法，包括将被研究的工程和物理科学方面的新知识或技术。该项目的方法论包括超导谐振器的设计、建模和纳米微制造，以及对新型自旋系统和材料宿主的研究。电子自旋共振将被用来研究自旋相干性和线宽特性，而注入和退火工艺将被优化以提高自旋性能。将使用稀释制冷机来实现高自旋极化，并确保超导量子比特的最佳操作。该项目与EPSRCS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正在进行的学术合作。

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.