Silicon Photonics for Quantum Computing

硅光子学最雄心勃勃的应用--Chrostowski的专长--是在量子计算方面。预计量子计算将带来信息技术的下一次飞跃，其预期影响与硅集成电路和互联网的发展一样重大。量子计算(QC)与经典计算的不同之处在于，存储比特信息的粒子(电子、光子)可以作为状态的线性组合(称为叠加)存在，而经典比特只能处于一种状态。叠加，再加上量子比特之间的关联(纠缠)，使量子计算机(QC)比经典计算机具有指数优势，在经典计算机中，即使是100个量子比特QC的性能也会超过拥有数万亿个经典晶体管的超级计算机。这将使我们能够解决一些世界上最紧迫的计算和社会问题，这些问题是经典计算机无法解决的。QC将在化学设计(例如用于碳捕获的酶)、材料设计(例如电池)、精确健康、优化和人工智能等领域实现突破。业界正在寻求几种硬件方法：领先的竞争者是基于超导(IBM、谷歌)和陷阱离子(IonQ、霍尼韦尔)量子比特的。新的竞争者是基于硅(Intel)和光子学(PsiQuantum，Xanadu)的自旋。这些基于硅的方法提供了扩展到数百万量子比特的潜力，这是由于设备尺寸小和晶片规模制造。目前有两家著名的硅光电子QC初创企业--加利福尼亚州的PsiQuantum和多伦多的Xanadu--分别筹集了5.09亿美元和3600万美元。这项提议旨在开发一种新的架构，有可能解决上述办法所面临的挑战。我们建议开发一种基于硅的平台，它使用注入的施主作为电子自旋量子比特，并使用光子学作为互连。这种混合电光方法利用了两个关键优势--电子可以产生极好的记忆(量子比特)，而光子可以很好地进行通信(纠缠)。这项研究计划将资助4名博士、3名MASC和8名本科生使用硅施主自旋量子比特设计、制造和测试用于量子计算的光子器件，长期目标是开发建立可扩展的容错QC所需的所有成分。学员将建造用于低温测试的实验设备，设计用于量子信息处理的新型纳米光子组件(单光子源和探测器，使用谐振器进行自旋量子比特到光子的耦合，低损耗光学开关)，使用最近CFI创新基金的基础设施开发新的制造技术，并演示可扩展体系结构中的量子比特操作。受训的HQP将能够将研究和技术转化为新的商业企业。

The most ambitious application for silicon photonics - Chrostowski's expertise - is in quantum computing. Quantum computing is expected to deliver the next leap in information technology, with anticipated impacts as significant as the development of silicon integrated circuits and the Internet. Quantum computing (QC) differs from classical computing in that particles (electrons, photons) that store bits of information (a quantum bit or "qubit") can exist as a linear combination of states (called superposition), whereas a classical bit can only be in one state. Superposition, together with correlations between qubits (entanglement), offer quantum computers (QCs) an exponential advantage over classical computers, where even 100 qubit QCs would outperform supercomputers with trillions of classical transistors. This would allow us to solve some of the world's most pressing computational and societal problems that are unsolvable by classical computers. QC will enable breakthroughs in fields as diverse as chemical design (e.g. enzymes for carbon capture), material design (e.g. batteries), precision health, optimization, and artificial intelligence. There are several hardware approaches being pursued in industry: the leading contenders are based on superconducting (IBM, Google) and trapped ion (IonQ, Honeywell) qubits. New contenders are based on spins in silicon (Intel) and photonics (PsiQuantum, Xanadu). These silicon-based approaches offer the potential for scaling to millions of qubits owing to the small device size and wafer-scale manufacturing. There are now two prominent silicon photonics QC start-ups, PsiQuantum in California, and Xanadu in Toronto, which have raised $509M and $36M, respectively. This proposal aims to develop a new architecture that has the potential to solve the challenges faced by the above approaches. We propose to develop a silicon-based platform that uses implanted donors as electron spin qubits with photonics used for the interconnects. This hybrid electro-optic approach makes use of two key advantages - electrons make excellent memories (qubits), while photons are excellent for communication (entanglement). This research program will fund 4 PhD, 3 MASc and 8 undergraduate students to design, fabricate, and test photonic devices for quantum computing using silicon donor spin qubits, with the long-term goal of developing all ingredients necessary to build a scalable fault-tolerant QC. Trainees will build experimental apparatus for testing at cryogenic temperatures, design novel nano-photonic components for quantum information processing (single photon sources and detectors, spin qubit to photon coupling using resonators, low-loss optical switches), develop novel fabrication techniques using infrastructure from a recent CFI Innovation grant, and demonstrate qubit operation in a scalable architecture. The HQP trained will be in a position to translate the research and technology into new commercial enterprises.