Pavel Gurevich, M.Sc. Thesis Seminar
Wednesday, 29.6.2011, 13:30
We present the first experimental realization of a new semi-classical quantum
key distribution (QKD) protocol called classical Alice (with mirror) and its
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
(not fully proved) 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) was
first proposed by Bennett and Brassard in 1984. This scheme was later proved to
be secure, and its security was proved 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 both parties "quantumness" can be relaxed without violating security.
The first 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 a variation of the
classical Alice protocol. Our setup which employs a novel idea (suggested by
Matty Katz) of a "sub-qubit" measurement using the rotating mirror approach.
This idea enables practical implementations of Alice side, and furthermore also
renders several attacks again real-world implementations of the original
classical Alice protocol impossible.