Fidelity and information in the quantum teleportation of continuous variables

Ideally, quantum teleportation should transfer a quantum state without distortion and without providing any information about that state. However, quantum teleportation of continuous electromagnetic-field variables introduces additional noise, limiting the fidelity of the quantum-state transfer. In this article, the operator describing the quantum-state transfer is derived. The transfer operator modifies the probability amplitudes of the quantum state in a shifted photon-number basis by enhancing low photon numbers and suppressing high photon numbers. This modification of the statistical weight corresponds to a measurement of finite resolution performed on the original quantum state. The limited fidelity of quantum teleportation is thus shown to be a direct consequence of the information obtained in the measurement.