Using of small-scale quantum computers in cryptography with many-qubit entangled states
K. V. Bayandin, G. B. Lesovik
L. D. Landau Institute for Theoretical Physics RAS, 117940, Moscow, Russia
PACS: 03.67.-a
Abstract
We propose a new cryptographic protocol. It is suggested to encode
information in ordinary binary form into many-qubit entangled
states with the help of a quantum computer. A state of qubits
(realized, e.g., with photons) is transmitted through a quantum
channel to the addressee, who applies a quantum computer tuned to
realize the inverse unitary transformation decoding the message.
Different ways of eavesdropping are considered and the estimation
of the time, needed for determining the secret unitary
transformation, is given. It is shown, that using even small
quantum computers can serve as a basis for very efficient
cryptographic protocols. For a suggested cryptographic protocol
the time scale on which communication can be considered secure is
exponential in the number of qubits in the entangled states and in
the number of gates used to construct the quantum network.