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We briefly review the security of the ping-pong protocol in light of several attack scenarios suggested by various authors since the proposal of the protocol.

Quantum mechanics has radically changed our classical conception of information and communication. The elementary unit of information, the „bit“, is replaced by the „qubit“ which

In the paper [Phys. Rev. A 69, 052319 (2004)], a quantum direct communication protocol is proposed which is claimed to be unconditionally secure even for

A physical theory is proposed that obeys both the principles of special relativity and of quantum mechanics. As a key feature, the laws are formulated

Diese Dissertation behandelt die Kodierung und Verschickung von Information durch einen Quantenkanal. Ein Quantenkanal besteht aus einem quantenmechanischen System, welches vom Sender manipuliert und vom

A novel secure communication protocol is presented, based on an entangled pair of qubits and allowing asymptotically secure key distribution and quasisecure direct communication. Since

In order to compress quantum messages without loss of information it is necessary to allow the length of the encoded messages to vary. We develop