Practical quantum cryptography : demonstration of secure commitments in the noisy storage model.

• Main Author: Ng, Nelly Huei Ying.
• Other Authors: Chew Lock Yue
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Science::Physics
• Online Access: http://hdl.handle.net/10356/49467
• Institution: Nanyang Technological University

The establishment of quantum theory has sparked further advancements in computer science and information theory. In this work, we explore aspects of quantum cryptography, showing how physical assumptions combined with fundamental laws of nature allow for secure communication, without additional computational assumptions as frequently invoked in many present-day cryptographic protocols. These progresses have wide applications, which can be used to perform tasks which lie in the central interest of modern cryptography, such as secure identi cation of a customer to an ATM machine. In particular, we have studied the bit commitment protocol within the scope of Noisy- Storage Model, and proved its robustness against experimental errors, demonstrating the feasibility of executing the protocol with real-world quantum devices. Having so, we conducted the implementation with actual optical devices. On the technical aspect, we developed a new set of uncertainty relations, which are extremely useful for actual implementations of protocols. These relations allow a signi cant reduction in the amount of classical information post-processing, directly shortening the computational time for secure two-party protocols in the model. Our approach involves the analytical optimization for a certain class of R enyi entropic measures conditioned on quantum measurements, which might be of independent interest.