Quantum Cryptography

量子信息处理与我们能用量子信息做什么和不能做什么有关，量子信息是量子系统状态下保存的物理信息，正如量子力学所预测的那样。由于量子纠缠、叠加、干涉和不可克隆等令人惊叹的现象，量子信息彻底改变了我们交流和计算的方式——例如，实现了超高速计算和安全通信。小规模量子计算技术已经存在；随着不断的努力，全面的量子计算成为现实只是时间问题。据悉，量子计算机带来的前所未有的计算能力可以彻底破解用于保护电子商务的密码。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），我们知道量子信息为通信提供了新的安全级别，挫败了超强大设备的任何攻击。**正如这个例子所说明的，我们正处于安全的十字路口：数字社会准备好迎接量子计算机的到来了吗？**我的研究旨在积极地回答这个问题，确保我们的信息基础设施在量子信息技术的存在下保持功能和安全。一方面，我处理来自超快速量子计算的威胁，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有量子计算的有效方法，而第二个问题是量子程序是否有可能隐藏自己的内部工作原理。

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.