On the Teleportation of Continuous Variable

The measurement procedures used in quantum teleportation are analyzed from the viewpoint of the general theory of quantum-mechanical measurements. It is shown that to find the teleported state one should only know the identity resolution (positive operator-valued measure) generated by the corresponding instrument (quantum operation describing the system state change caused by the measurement) rather than the instrument itself. A quantum teleportation protocol based on a measurement associated with a non-orthogonal identity resolution is proposed for a system with non-degenerate continuous spectrum.Comment: 13 pages, no figures. To be published in JET

Relativistic quantum coin tossing

A relativistic quantum information exchange protocol is proposed allowing two distant users to realize ``coin tossing'' procedure. The protocol is based on the point that in relativistic quantum theory reliable distinguishing between the two orthogonal states generally requires a finite time depending on the structure of these states.Comment: 6 pages, no figure

Quantum Cryptography Based on the Time--Energy Uncertainty Relation

A new cryptosystem based on the fundamental time--energy uncertainty relation is proposed. Such a cryptosystem can be implemented with both correlated photon pairs and single photon states.Comment: 5 pages, LaTex, no figure