Technical Report MSC-2013-19

Title: Experimental Quantum Key Distribution with Clasical Alice
Authors: Pavel Gurevich
Supervisors: Meir Orenstein, Tal Mor
Abstract: We present the first experimental realization of a new semi-classical quantum key distribution (SQKD) protocol called classical Alice (with mirror) and its security analysis.

The field of quantum information and computation is relatively new and rapidly emerging field of science, and secure key distribution is one of the most prominent practical applications in this area. Unlike other conventional key distribution schemes — to which we refer as classical — that rely on assumptions in mathematics and complexity theory, quantum key distribution relies on quantum physics imposed rules to gain its security.

Secure key distribution scheme based on quantum carriers (quantum bits — two-level systems) was first proposed by Bennett and Brassard in 1984. This scheme was later proven to be secure: its security was proven against the most general kind of attacks, thus making schemes using this protocol information secure.

Originally, quantum key distribution schemes demanded that both parties have quantum abilities. In 2007, it was shown (at the Technion) that the requirement for "quantumness" of both parties can be relaxed while still having security. The first such protocol, QKD with classical Bob, was followed by a simpler one, QKD with classical Alice which we have implemented and analyzed. We describe a free space based setup that uses visible light to implement the classical Alice protocol. Our setup employs a novel idea (suggested by Matty Katz) of a "sub-qubit" measurement using the rotating mirror approach.

The rotating mirror idea enables practical implementations of Alice’s side, and furthermore also prevents several attacks against real-world implementations of the original classical Alice protocol. We implemented working experimental system based on this design in our laboratory. This work describes both the design and its analysis.

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