Non-Gaussian operations in measurement device independent quantum key distribution

TL;DR

This paper explores how various non-Gaussian operations on squeezed coherent states can enhance the transmission distance in measurement device independent quantum key distribution, with photon catalysis being particularly effective.

Contribution

It introduces a generalized covariance matrix for non-Gaussian states and demonstrates the benefits of photon addition, catalysis, and subtraction in CV MDI QKD.

Findings

Zero photon catalysis on TMSC extends transmission distance to nearly 70 km.

Single photon subtraction also achieves around 70 km transmission distance.

The generalized covariance matrix aids in analyzing non-Gaussian states in CV quantum information.

Abstract

Non-Gaussian operations in continous variable (CV) quantum key distribution (QKD) have been limited to photon subtraction on squeezed vacuum states only. This is mainly due to the ease of calculating the covariance matrix representation of such states. In this paper we study the effects of general non-Gaussian operations corresponding to photon addition, catalysis and subtraction on squeezed coherent states on CV measurement device independent (MDI) QKD. We find that non-Gaussianity coupled with coherence can yield significantly longer transmission distances than without. Particularly we observe that zero photon catalysis on two mode squeezed coherent state (TMSC) is an optimial choice for CV MDI QKD, while single photon subtraction is also a good candidate; both of them offering nearly 70 km of transmission distances. We also derive a single generalized covariance matrix for the aforementioned states which will be useful in several other aspects of CV quantum information processing.