Analog Quantum Teleportation

TL;DR

This paper explores analog quantum teleportation protocols that replace classical communication with noisy quantum channels, demonstrating their superiority over digital protocols under certain entanglement-preserving conditions, especially in microwave superconducting circuits.

Contribution

It provides analytical conditions for when analog teleportation outperforms digital methods, applying Gaussian-channel theory to optimize quantum state transfer over lossy channels.

Findings

Analog protocols outperform digital ones when channels do not reduce entanglement.

Optimality of analog protocols for a range of channel transmissivities.

Relevance for microwave superconducting circuit communication links.

Abstract

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.