Investigating deep defects in 28Si for potential applications in quantum information and communication

我们的现代技术是基于量子力学能够完美地(如果只是概率地)描述纳米系统的行为的能力。越来越多的人认识到，量子力学的原理可以更直接地用于新的“量子技术”，这些技术在通信、安全和计算领域具有巨大的潜力，可以应用于全新的和潜在的颠覆性应用。在量子计算机(QC)中，叠加允许将传统计算机比特的0和1替换为0和1的无限范围的叠加，从而得到量子比特或量子比特。量子比特可以使用纠缠连接在一起，因此一个量子比特上的测量结果会影响另一个量子比特测量的结果，即使是分开的。这违背了我们的直觉，因为它是基于宏观现实的，但完全可以用量子力学来解释。我们现在知道，对于某些类别的重要问题，QC可能比可以想象的最大的传统计算机强大得多，速度也快得多。这种范式转换的潜力正在推动世界各地的紧张研究，以找到一种技术来制造足够复杂的QC来解决这类广泛的问题。人们正在研究一系列系统，从光子到原子，再到亚原子粒子，如电子和核自旋。许多活动都集中在基于硅的方法上，因为硅是我们目前计算和信息技术的基础。如果能开发出合适的量子比特及其制备、耦合和测量手段，就可以利用现有的硅材料科学和纳米器件技术来构建QC。我们的发现富含28Si具有一个独特的性质：28Si中的光学跃迁线宽比正常硅(或任何其他半导体)中的要尖锐得多，这导致了控制和测量杂质的电子和核自旋的新方法，这是Si中量子比特的主要候选者。这些技术展示了创纪录的相干寿命--一个量子比特可以保持的时间--这引起了全球的极大关注，包括物理学年度十大突破(2013)。使用这些相同的技术，我们最近发现了使高度可重复性的单光子源与硅光子学兼容的全新可能性，这满足了那些试图建立基于光子的量子技术的人的突出需求。这些激动人心的单光子源还提供了一种将芯片上的多个量子比特与单个光粒子联系起来的方法，为实现大规模的硅基QC铺平了道路。这笔赠款将使我们能够在我们的成就和合作的基础上再接再厉，并继续在这一领域设定新的方向。具体而言，我们将培养未来的领导者，他们将配备半导体、光学、低温和量子信息理论方面的专业知识，他们将为实现量子技术的承诺做出贡献。

Our modern technology is based on the ability of quantum mechanics to describe perfectly (if only probabilistically) the behavior of nanoscale systems. There is a growing appreciation that the principles of quantum mechanics can be used more directly in new `quantum technologies', which have spectacular potential for completely new and potentially disruptive applications in communications, security, and computing. In a quantum computer (QC), superposition allows the 0 and 1 of a conventional computer bit to be replaced by an infinite range of superpositions of 0 and 1, giving a quantum bit, or qubit. Qubits can be linked using entanglement so that a measurement on one affects the outcome of a measurement on the other, even when separated. This defies our intuition, based as it is on macroscopic reality, but can be completely accounted for by quantum mechanics. We now know that for certain classes of important problems, a QC could be enormously more powerful and faster than the largest imaginable conventional computer. This paradigm-shifting potential is fueling intense research around the world to find a technology for making a QC of sufficient complexity to solve this broad class of problems. A wide range of systems is being investigated, from photons to atoms to subatomic particles such as electrons and nuclear spins. Much activity is focused on silicon (Si)-based approaches, since Si is the basis for our present computing and information technologies. The existing Si materials science and nanoscale device technology could be harnessed to build a QC, if suitable qubits and the means of preparing, coupling and measuring them can be developed. Our discovery that enriched 28Si has a unique property: the linewidths of optical transitions are much sharper in 28Si than in normal Si (or in any other semiconductor), led to new methods for controlling and measuring the electron and nuclear spins of impurities, which are prime candidates for qubits in Si. These techniques demonstrated record-setting coherence lifetimes - the time for which a qubit can be maintained - which attracted significant global attention, including a Physics World Top Ten Breakthrough of the Year (2013). Using these same techniques, we recently identified entirely new possibilities for making highly reproducible single photon sources compatible with Si photonics, which addresses an outstanding need for those trying to build photon-based quantum technologies. These exciting single photon sources also offer a way to link multiple qubits on-chip with individual particles of light, paving the way towards a large-scale silicon-based QC. This grant will allow us to build on our achievements and collaborations, and to continue to set new directions in this field.  Specifically, we will train future leaders, equipped with expertise in semiconductors, optics, cryogenics and quantum information theory, who will contribute to making the promise of quantum technologies a reality.