Quantum Cryptography

量子信息处理涉及我们可以和不可以对量子信息做什么，正如量子力学预测的那样，量子信息是保持在量子系统状态中的物理信息。由于纠缠、叠加、干涉和不可克隆等惊人现象，量子信息彻底改变了我们的通信方式和计算能力--例如，超高速计算和安全通信。小规模量子计算的技术已经存在；通过不断的努力，全面量子计算成为现实只是个时间问题。众所周知，量子计算机带来的前所未有的计算能力可以完全破解用于保护电子商务安全的密码。幸运的是，由于量子密钥分发(量子信息处理中最早的发现之一)，我们知道量子信息使通信的安全达到了一个新的水平，挫败了任何超强大设备的攻击。正如这个例子所表明的那样，我们正处于安全方面的十字路口：数字社会是否为量子计算机的出现做好了准备？我的研究旨在肯定地回答这个问题，确保我们的信息基础设施在量子信息技术存在的情况下保持功能和安全。一方面，我处理来自超高速量子计算的威胁，另一方面，我利用量子信息的特性来提供安全的解决方案。我将探讨两个主要问题；第一个是研究委托私人量子计算的有效方法，第二个问题是量子程序是否有可能隐藏自己的内部工作。

Quantum information processing is concerned with what we can and cannot do with quantum information, which is the physical information that is held in the state of a quantum system, as predicted by quantum mechanics. Thanks to amazing phenomena such as entanglement, superposition, interference and no-cloning, quantum information revolutionizes the way we communicate and compute — enabling, for instance, ultra-fast computations and secure communications. Already, the technology for small-scale quantum computing exists; with continued effort, it is just a matter of time until full-scale quantum computing becomes a reality. The unprecedented computing power brought forth by quantum computers is known to completely break the cryptographic codes used to secure e-commerce. Fortunately, thanks to quantum key distribution (one of the earliest discoveries in quantum information processing), we know that quantum information enables a new level of security for communications, thwarting any attack by ultra-powerful devices.As this example illustrates, we are sitting at a crossroads in terms of security: is the digital society ready for the advent of quantum computers?My research aims at answering this question in the positive, ensuring that our information infrastructure remains both functional and secure in the presence of quantum information technologies. On one hand, I deal with the threats that stem from ultra-fast quantum computations, while on the other, I exploit the properties of quantum information in order to provide secure solutions. I shall explore two major questions; the first is the study of efficient methods of delegating private quantum computations, while the second asks if it is possible for a quantum program to hide its own inner workings.