Analog Quantum Teleportation

Digital teleportation protocols make use of entanglement, local measurements and a classical communication channel to transfer quantum states between remote parties. We consider analog teleportation protocols, where classical communication is replaced by transmission through a noisy quantum channel. We show that analog teleportation protocols outperform digital protocols if and only if Alice and Bob are linked by a channel that does not reduce entanglement when applied to a part of the resource state. We first derive general analytical results in the broader context of Gaussian-channel simulation. Then, we apply it to the quantum teleportation of a uniformly distributed codebook of coherent states, showing that an analog protocol is optimal for a wide range of communication channel transmissivities. Our result contributes to mitigating noise in the intermediate case when the communication channel is far from being ideal but is not too lossy, as is the case of cryogenic links in microwave superconducting circuits.