ERROR-FREE QUANTUM COMMUNICATION THROUGH NOISY CHANNELS

We suggest a method to perform a quantum logic gate between distant qu antum bits (qubits) by off-resonant field-atom dispersive interactions . The scheme we present is shown to work ideally even in the presence of errors in the photon channels used for communication. The stability against errors arises from the paradoxical situation that the transmi tted photons carry no information about the state of the qubits. In co ntrast to a previous proposal for ideal communication [Phys. Rev. Lett . 78, 4293 (1997)] our proposal only involves single atoms in the send ing and receiving devices. [S1050-2947(98)11809-7].