Fabricating a photonic quantum computer

量子力学是在一个世纪前发展起来的，它描述了一个微观世界，这个世界基本上是概率的，一个物体可以同时在两个地方叠加，两个遥远的物体可以瞬间连接在一起——纠缠。从那以后，理解这些不寻常的性质一直是（元）物理辩论的主题。最近，人们的注意力集中在利用这些特性来显著提高信息和通信任务的能力和功能的潜力上——量子信息技术（QITs）。这些新技术的影响将是深远的：为消费者、企业和政府提供安全的通信网络；用于生物医学技术和环境监测的精密传感器；用于设计新材料、药品和清洁能源设备的超强量子计算机。随着这些技术的成熟，新的应用将不可避免地出现在医疗技术、国防和安全等领域。然而，设计和控制量子系统是一项巨大的技术挑战：它们本质上是脆弱的；从量子系统中提取的信息必然会干扰系统本身。

Quantum mechanics was developed a century ago to describe a microscopic world that is fundamentally probabilistic, where a single object can be in two places at once-superposition-and where two objects in remote locations can be instantaneously connected-entanglement. Understanding these un- usual properties has been the topic of (meta-) physical debate ever since. More recently attention has focused on the potential for harnessing these properties for dramatic improvements in the power and functionality of information and communication tasks- quantum information technologies (QITs).The impact of these new technologies will be profound and far-reaching: secure communication networks for consumers, corporations and government; precision sensors for biomedical technology and environmental monitoring; ultra-powerful quantum computers for the design of new materials, pharmaceuticals and clean energy devices. As these technologies mature new applications will inevitably emerge in fields such as medical technology, defence and security. However, engineering quantum systems and controlling them is an immense technological challenge: they are inherently fragile; and information extracted from a quantum system necessarily disturbs the system itself.