# Discrete-modulation continuous-variable quantum key distribution enhanced by quantum scissors

## TL;DR

This paper demonstrates that quantum scissors can significantly improve the performance of discrete-modulation CV-QKD protocols, enabling positive secret key rates under high loss and noise, thus supporting long-distance quantum communication.

## Contribution

It extends the application of quantum scissors to discrete-modulation CV-QKD, showing their effectiveness in noisy, long-distance regimes and maintaining the viability of quantum repeaters.

## Key findings

- Quantum scissors enable positive secret key rates at high loss.
- They improve performance in noisy, long-distance regimes.
- Support for quantum repeaters in discrete-modulation CV-QKD.

## Abstract

It is known that quantum scissors, as non-deterministic amplifiers, can enhance the performance of Gaussian-modulated continuous-variable quantum key distribution (CV-QKD) in noisy and long-distance regimes of operation. Here, we extend this result to a non-Gaussian CV-QKD protocol with discrete modulation. We show that, by using a proper setting, the use of quantum scissors in the receiver of such discrete-modulation CV-QKD protocols would allow us to achieve positive secret key rates at high loss and high excess noise regimes of operation, which would have been otherwise impossible. This also keeps the prospect of running discrete-modulation CV-QKD over CV quantum repeaters alive.