Quantum Cryptography

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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.