Significance of Fidelity Deviation in Continuous Variable Teleportation

TL;DR

This paper introduces the fidelity deviation as a second figure of merit for continuous variable quantum teleportation, providing a more comprehensive assessment of protocol performance beyond average fidelity, especially under various noise conditions.

Contribution

It proposes considering both average fidelity and fidelity deviation to better characterize CV teleportation performance, including in noisy environments and different input state distributions.

Findings

Fidelity deviation complements average fidelity in evaluating CV teleportation.

Certain noise types can enhance protocol robustness through constructive effects.

Different input state distributions affect teleportation performance classification.

Abstract

Performance of quantum teleportation is typically measured by the average fidelity, an overlap between the input and output states. Along with the first moment, we introduce the second moment of fidelity in CV teleportation, i.e., the fidelity deviation as the figures of merit to assess the protocol's efficiency. We show that CV states, both Gaussian and non Gaussian, can be better characterized by considering both average fidelity and fidelity deviation, which is not possible with only average fidelity. Moreover, we shed light on the performance of the teleportation protocol in two different input scenarios - one is when input states are sampled from constrained uniform distribution while the other one is Gaussian suppression of the input states which again lead to a different classification of CV states according to their performance. The entire analysis is carried out in noiseless and noisy scenarios with noise being incorporated in the measurement and the shared channels. We also report that one type of noise can make the protocol robust against the other one which leads to a `constructive effect' and identify the noise models which are responsible for decreasing average fidelity and increment in fidelity deviation.