# Coherence assisted non-Gaussian measurement device independent quantum key distribution

## TL;DR

This paper demonstrates that combining coherence and non-Gaussian operations, specifically photon subtraction on two mode squeezed coherent states, significantly enhances the transmission distances in continuous variable measurement device independent quantum key distribution, with practical feasibility.

## Contribution

It introduces a generalized covariance matrix for PSTMSC states and shows how coherence and non-Gaussianity together improve CV-MDI-QKD performance beyond previous methods.

## Key findings

- Photon subtraction on PSTMSC states extends transmission distances.
- Coherence and non-Gaussianity synergistically enhance protocol performance.
- Technique is experimentally feasible with realistic parameters.

## Abstract

Non-Gaussian operations on two mode squeezed vacuum states (TMSV) in continuous variable measurement device independent quantum key distribution (CV-MDI-QKD) protocols have been shown to effectively increase the total transmission distances drastically. In this paper we show that photon subtraction on a two mode squeezed coherent (PSTMSC) state can further improve the transmission distances remarkably. To that end we also provide a generalized covariance matrix corresponding to PSTMSC, which has not been attempted before. We show that coherence, defined as the amount of displacement of vacuum state, along with non-Gaussianity can help improve the performance of prevalent CV-MDI-QKD protocols. Furthermore, since we use realistic parameters, our technique is experimentally feasible and can be readily implemented