Quantum Digital Signatures without quantum memory

TL;DR

This paper introduces a quantum digital signature scheme that does not require quantum memory, enabling secure message exchange with quantum guarantees using only linear optics, making it practical with current technology.

Contribution

The paper presents the first quantum digital signature protocol that eliminates the need for quantum memory, simplifying implementation with existing linear optical technology.

Findings

QDS can be implemented without quantum memory

The scheme is feasible with current linear optical technology

Provides quantum-secure message authentication

Abstract

Quantum Digital Signatures (QDS) allow for the exchange of messages from one sender to multiple recipients, with the guarantee that messages cannot be forged or tampered with. Additionally, messages cannot be repudiated -- if one recipient accepts a message, she is guaranteed that others will accept the same message as well. While messaging with these types of security guarantees are routinely performed in the modern digital world, current technologies only offer security under computational assumptions. QDS, on the other hand, offer security guaranteed by quantum mechanics. All thus far proposed variants of QDS require long-term, high quality storage of quantum information, making them unfeasible in the foreseeable future. Here, we present the first QDS scheme where no quantum memory is required, and all quantum information processing can be performed using just linear optics. This makes QDS feasible with current technology.