No real advantage of photon subtraction and displacement in continuous variable measurement device independent quantum key distribution

TL;DR

This paper demonstrates that photon subtraction and displacement do not enhance the performance of continuous variable measurement device independent quantum key distribution, challenging previous assumptions about their utility.

Contribution

It provides a critical analysis showing that SPS and displacement do not improve CV-MDI-QKD, prompting a reevaluation of non-Gaussian operations in quantum protocols.

Findings

Photon subtraction offers no loss tolerance benefits in CV-MDI-QKD.

Displacement does not improve CV-MDI-QKD performance.

Questions the effectiveness of non-Gaussian operations in quantum communication.

Abstract

We critically analyse the role of single photon subtraction (SPS) and displacement in improving the performance of continuous variable measurement device independent quantum key distribution (CV-MDI-QKD). We consider CV-MDI-QKD with resource states generated by SPS on a displaced two-mode squeezed vacuum state. Optimizing the secret key rate with state parameters reveals that implementing SPS yields no benefits in improving the loss tolerance of CV-MDI-QKD. Additionally, we find that displacement too is not useful in improving the performance of CV-MDI-QKD. While our result is in contradistinction with the widely held belief in the field regarding the utility of SPS and displacement in CV-MDI-QKD, it also calls for a re-examination of the role of non-Gaussian operations in increasing the efficiency of various quantum information processing protocols.