# Experimental measurement-device-independent quantum digital signatures

## TL;DR

This paper presents an experimental implementation of a reconfigurable quantum key distribution scheme that enables real-time switching between conventional and measurement-device-independent QKD, and demonstrates quantum digital signatures over a network.

## Contribution

It introduces a reconfigurable QKD setup capable of switching modes and demonstrates the first quantum digital signatures over an MDI link with improved rate protocols.

## Key findings

- Successful distribution of quantum keys among three parties with two channels
- First quantum digital signature rates achieved over an MDI network
- Enhanced signature rates through efficient data distillation protocol

## Abstract

We propose and experimentally implement a novel reconfigurable quantum key distribution (QKD) scheme, where the users can switch in real time between conventional QKD and the recently-introduced measurement-device-independent (MDI) QKD. Through this setup, we demonstrate the distribution of quantum keys between three remote parties connected by only two quantum channels, a previously unattempted task. Moreover, as a prominent application, we extract the first quantum digital signature (QDS) rates from a network that uses a measurement-device-independent link. In so doing, we introduce an efficient protocol to distil multiple signatures from the same block of data, thus reducing the statistical fluctuations in the sample and increasing the final QDS rate.